Effects of Phoenix dactylifera against Streptozotocin-Aluminium Chloride Induced Alzheimer’s Rats and Their In Silico Study

Abstract

Phoenix dactylifera is known for medicinal importance due to its antioxidant, antidiabetic, antidepressant, and anti-inflammatory properties. This study is aimed at evaluating the effect of P. dactylifera seeds to cure Alzheimer’s disease (AD). AD was induced in the rats with streptozotocin + aluminium chloride followed by treatment of methanolic extract of P. dactylifera seeds. The blood glucose levels were determined at regular intervals, which showed a prominent decrease in the extracts treated group. Behavior tests, including the Elevated Plus Maze (EPM) test and Morris Water Maze (MWM) test, were used to evaluate memory patterns in rats. The results indicated that extract-treated rats significantly improved memory behavior compared to the diseased group. After dissection, the serum electrolytes, antioxidant enzymes, and choline esterase enzymes were measured in different organs. The serum parameters creatinine, urea, and bilirubin increased after extract treatment. Similarly, the level of antioxidant enzymes like peroxidases (POD), glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and thiobarbituric acid reactive substance (TBARS) in the extract-treated group showed improved results that were close to the normal control group. The enzyme (lipase, insulin, amylase, and acetylcholine) levels were found enhanced in extract groups as compared to diseased rats. High-performance liquid chromatography (HPLC) was used to determine the level of dopamine and serotonin neurotransmitters, which were increased significantly for P. dactylifera seeds with values of 0.18 μg/mg tissue and 0.56 μg/mg tissue, respectively. Overall, results showed that P. dactylifera seeds proved to be quite efficient in improving the memory and behavior of treated rats. The antioxidants and enzymes were also increased; therefore, it may be a potential candidate for treating AD.

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1. Introduction

Metabolic disorders impose a substantial burden on human health around the globe. Among the top ten leading causes of mortality, diabetes mellitus ranks fifth due to the relatively expensive treatment and development of other disabilities [1, 2]. It has been analyzed through the survey that diabetes prevalence in 2021 was assessed as 10.5% (536.6 million people), rising to 12.2% (783.2 million) in 2045 [3]. Diabetes is a genetically and clinically heterogeneous chronic metabolic disease characterized by an elevated glucose level in the blood and metabolic disorders of lipids, proteins, and carbohydrates. Moreover, this disease is also correlated with several other complications, which are not reversible in several cases [4].

AD is one of the critical complications of diabetes [2, 5]. This disease is a chronic progressive and devitalizing brain disorder that has severe effects on intelligence, memory, and self-care. The significant causes responsible for the onset of Alzheimer’s include a gradual decrease in energy metabolism, brain glucose, skeletal cellular system, nerve flexibility, and myelin retention [5–7]. Several researchers have supported the concept that the metabolic disturbances signaled by IGF (insulin-like growth factor) and insulin deficiencies are responsible for the development of Alzheimer’s [2, 8].

Moreover, a study has analyzed that type 2 diabetes (T2D) almost doubles the risk of developing dementia [9, 10]. The study conducted by Madmoli et al. [2] has also revealed the prevalence of AD in almost all diabetic patients above the age of 60 years, which can be indicative of the contingency of developing Alzheimer’s in diabetic patients. AD is the most predominant form of dementia, and until today, there is no treatment capable of slowing down, stopping, or significantly reversing the progression of this disease [1, 11]. An elevated blood glucose level in nondiabetic people escalates the risk of developing dementia by 18%, linked with cognitive reduction and decline of hippocampal volume [1, 12, 13]. Moreover, the incidence of Alzheimer’s is positively associated with hyperglycemia and hyperinsulinemia [14, 15].

Studies revealed that the proinflammatory mechanisms responsible for triggering peripheral insulin resistance in diabetes mellitus induce neuronal dysfunction in AD [1]. Type 2 diabetes mellitus (T2DM) causes the activation of glycogen synthase kinase 3 beta (GSK3β), amyloid-beta production, low production of adenosine triphosphate (ATP), phosphorylation of tau, impaired mitochondrial function, cognitive impairments, activation of wingless-related integration site/beta catenin (Wnt/β-catenin) pathway, and increased production of free radicals [16]. All these conditions are found to be similar to the conditions of Alzheimer’s dementia, and that is the reason why AD is also termed “ type 3 diabetes (T3D),” which is recently reported as the sixth preeminent cause of death around the globe [17]. Moreover, the social and fiscal burden of both these diseases is immense, and scientists are relentlessly working to find more effective and novel strategies for diagnosing, preventing, and treating these diseases.

However, natural herbs and their constituents are a suitable substitute for allopathic medicines for diabetes for being less toxic and have lesser side effects. It has been estimated that approximately 25% of people in developed counties and 75–80% of people living in developing countries are either indirectly or directly dependent on medicinal plants and herbs as a source of the first line of treatment due to affordability, availability, convenience, and acceptability [18]. Among these valuable traditional medical plants, Phoenix dactylifera, commonly known as ajwa date, is the most significant one, which belongs to the family Arecaceae [19]. Phoenix dactylifera not only poses excellent prominence from the nutritional, medicinal, and economic points of view but its significance has also been cited in the Holy Quran. Recently, strategies for treating several diseases have been concentrated on advancing novel remedial options with lesser or no side effects. Traditions (Sunnah) of Prophet Muhammad (Sallahu Alayhi Wa Salaam) promote the predate use of P. dactylifera as medicine for several centuries, acting as a prototype for the conventions of modern treatment [20]. P. dactylifera possesses high therapeutic attributes against many health disorders and confers medicinal and nutritional benefits [20]. The date fruit, a rich source of sugars and minerals, contains varied constituents such as flavonoids, carotenoids, phytochemicals, and steroids, which have been screened for several therapeutic activities [19]. The therapeutic effects of P. dactylifera and its constituents have been alleged since antiquity. It has been abundantly used as an antitussive, restorer, laxative, demulcent, and diuretic in Ayurveda (the traditional system of medicine in India) [21]. Moreover, it was also used to treat disorders of the reproductive and endocrine systems [21]. Other tree parts of P. dactylifera, such as pollens, fruits, leaves, pits, and their derivatives, have been passed down in numerous folk and traditional systems of medicines to cure different health disorders and diseases [21]. Historically, this practice of using dates for treating disease has been intensely adopted by specific cultures, including Iraq, Algeria, Iran, Egypt, Morocco, and India. In South-Eastern Morocco, dates are mainly used to treat diabetes and hypertension [21].

In addition, the compositional analysis of P. dactylifera has exhibited potent antioxidant, antimicrobial, anti-inflammatory, neuroprotective, immunostimulant, hepatoprotective, antiviral, gastroprotective, and anticarcinogenic properties [22]. The carotenoids, tannins, and polyphenols found in the ajwa seeds and flesh are prominently known for their antioxidant properties [22]. These natural antioxidants serve many therapeutic roles against heart diseases, protecting against microbes, cancer prevention, and protecting against the onset of mutagenic properties [22]. Raw ajwa dates have been used in Palestine’s Traditional medicine systems to treat breast cancer in women [23].

Besides this, Zhang et al. [23] has also found that the cyclooxygenase inhibitory property in P. dactylifera resembles naproxen, aspirin, and ibuprofen. Due to this, it possesses strong anti-inflammatory properties against gastrointestinal disturbances, arthritis, chronic pulmonary diseases, and asthma [22]. Not only is this, but ajwa date is also used for sharpening this memory. In Turkey, a unique herbal coffee called “Hurma” is made from the date’s seeds and consumed to improve memory [22]. Moreover, the antioxidant activity of ajwa date and its constituents could also help in preventing or savaging the production of free radicals linked with the onset of AD. Low glycemic index (GI) diets such as dates with a low GI are effective in managing diabetes mellitus [20].

Despite several uses of date palms in traditional and historical medicine, there is little scientific or clinical evidence available to confirm or support the effects of P. dactylifera against diabetes and Alzheimer’s. Nevertheless, the research related to the analysis of bioactive compounds present in P. dactylifera conducted in the last few decades has widened our knowledge and understanding of the possible mechanisms that could help us to authenticate the basis of archival health claims. This research study focuses on exploring the medicinal qualities of P. dactylifera against diabetes and Alzheimer’s induced in rat models to analyze the therapeutic effects of this traditional medicinal plant with lesser side effects.

2. Materials and Methods

2.1. Plant Material and Extract Preparation

Fresh ajwa dates were taken from the market of Madina, Saudi Arabia. The seeds were separated from the date fruit and ground to a fine powder using a pestle and mortar. The dried powdered material was macerated in 99% methanol for 14 days, and the solvent was separated using a rotary evaporator. Then, it was filtered using the Whatman filter paper No.1 several times until maximum extraction was achieved. The filtered extract was dried under vacuum at 40°C and stored at -20°C until further use.

2.2. Animals and Treatment Groups

Sprague Dawley rats weighing 220-250 g were selected for the experiment and were kept in aluminium cages where proper diet and water were provided. This experiment was performed in the Primate Facility of Quaid-i-Azam University, Islamabad (QAU). This study was approved by the Institutional Ethics and Biosafety Committee (IBC) under number 320. Minimal animal suffering was accomplished throughout the experiment, and all the National Institute of Health (NIH) guidelines were followed. IBC approved the experimental authenticity after review and inspection. The rats were divided into eight groups, each containing five rats. The groups were divided as normal control, diabetes disease control, diabetes-positive control Glibenclamide, AD control, Alzheimer’s positive control (Rivastigmine), and Phoenix dactylifera seed extract groups at three different concentrations of 100 mg/kg, 200 mg/kg, and 400 mg/kg. Diabetes was induced in all groups by intraperitoneal (0.2 ml) injection of 30 mg/kg streptozotocin (STZ) for three consecutive days. Diabetes disease control received 0.9% saline (10 ml/kg/body weight) after STZ injection at concentration of 10 mg/kg/body weight. Diabetes-positive control received the drug Glibenclamide after STZ injection. Alzheimer’s disease control received 0.9% saline + aluminium chloride (AlCl₃) (10 ml/kg/body weight) after STZ injection. Alzheimer’s positive control received Rivastigmine drug+AlCl₃ (100 mg/kg) at concentration of 10 mg/kg/body weight after injection. P. dactylifera seed extracts group received 100, 200, and 400 mg/kg/body weight seed extract+AlCl₃ (100 mg/kg), respectively, after STZ injections. The doses were given orally on alternate days for 21 days after the disease was induced. Lifescan One-touch Vita™ test meter was used to check the blood glucose level of the rats up to 21 days [24].

2.3. Elevated Plus Maze Test

After the 14^th day of dosage, rat’s anxiety behavior was analyzed using the Elevated Plus Maze (EPM) [24, 25]. It was a plus-shaped apparatus where two sides were surrounded, making it the closed-arm end, and two sides were exposed, making them an open-arm end. Each rat was first left over the maze for some time to get familiar with the apparatus. The rats were then let into the maze one by one facing towards the open-arm end. The movement of each rat in the maze was recorded for a time interval of 5 minutes by the camera mounted on the stand. The videos recorded were then analyzed for time spent in open and closed arms, the number of entries in each arm, and the distance travelled in both arms of the maze using ANY-maze video tracking software.

2.4. Morris Water Maze Test

After the 14^th day of dosage, the memory patterns were evaluated by the Morris Water Maze (MWM) test [24, 26]. A circular pool of 90 cm in diameter was filled with water, and a platform was placed in it. The protocol consisted of visible and hidden trials for each rat and a probe trial at the end. The platform was above the water surface and visible to rats in the visible trial. The rat was left in the pool, and the time was noted when it reached the platform. Each rat in the pool had a total time of 60 seconds. The hidden trial was performed the next day, where the platform was placed underwater, and colour was added to the water so the rat did not see the platform. The same experiment was repeated as with the visible trial. After the hidden trial, the platform was removed, and each rat was let into the pool for a probe trial for 60 seconds. In this way, the memory status of rats was checked that how much memory rats retained in locating the platform based on its previous trials. The movement was recorded by a camera mounted on a stand which was analyzed by ANY-maze video tracking software.

2.5. Dissection of Rats and Tissue Preparation

On the 21^st day, the rats were anaesthetized with isoflurane by administering a mixture of nitrous oxide/oxygen (N₂O/O₂) with 32-36% oxygen concentration. Rats were placed in a plastic container, and a silicon tube was used to let in the gas mixture. The vaporizer was used to induce anaesthesia via inhalation of 4% vaporized isoflurane. The rats were anaesthetized in a few seconds [27]. The rats were dissected, and the blood was obtained with a 3 ml syringe by cardiac puncture in BD vacutainer® tubes [28]. The organs are extracted, which include the kidney, liver, brain, and pancreas. The tissues prepared for histopathology were stored in formalin. The tissue sample extracted for bioassays and high-performance liquid chromatography (HPLC) analysis were stored in normal saline solution.

2.6. Serum Analysis

The serum obtained after centrifugation was analyzed according to the supplier’s standard kits level using the Cobas® kits and standard protocols as reported previously [29, 30]. The compounds analyzed included total serum protein, total serum bilirubin, blood urea nitrogen (BUN), serum creatinine, serum alanine transaminase (ALT), and serum aspartate transaminase (AST). The organ tissues stored in saline solution were subjected to homogenization.

2.7. Insulin and Lipase Levels of Pancreas

The insulin and lipase levels were measured according to the guidelines on the supplier’s standard kits using the Cobas® kits (Roche Diagnostics, USA). The insulin test was critical in examining the overall effects of P. dactylifera seeds as it directly measures the level of insulin in rats [31]. Lipase enzyme helps the body in breaking down the fats in the intestine. Any fluctuation in its level is considered an abnormality.

2.8. α-Amylase Assay

The assay was carried out according to the procedure [30, 32]. The starch solution was prepared in potassium phosphate buffer at a 20 mg/ml. The reaction mixture consisted of starch solution, buffer, and sample, which was incubated for 30 min at 50°C. After incubation, an iodine solution was added to each well, and the reading was calculated at 540 nM.

2.9. Acetylcholine Analysis

Choline esterase assay was used to measure the amount of acetylcholine in the brain tissues. These were measured by some modifications in Ellman’s method [30, 33]. For the acetylcholine inhibition assay, acetylthiocholine iodide (AChI), sample, and buffer were added to the reaction mixture. The absorbance was measured at 412 nM on a microplate reader.

2.10. Determination of Antioxidant Enzymes of Organs

The tissues excised after dissection were subjected to various assays to determine antioxidant enzymes. The total protein present in the sample was measured by some modifications in the Bradford assay [34]. The essay was performed in a microtiter plate and absorbance was measured at 595 nM in a microplate reader. The proteins were expressed as μg/mg tissue. The peroxidase enzyme responsible for reducing reactive oxygen species was measured by peroxidases (POD) assay [35]. The activity was measured by taking absorbance at 470 nM in a microplate reader. POD was expressed as U/min. The amount of reduced glutathione (GSH) was measured by Ellman’s method [36]. The absorbance was taken at 412 nM in a microplate reader. GSH was expressed as mM/g tissue. The lipid peroxidation was measured in tissues by thiobarbituric acid reactive substance (TBARS) estimation [37]. The absorbance was measured by a microplate reader at 540 nM. TBARS was expressed as nM/min/mg tissue. The oxidases present in tissues were measured by catalase (CAT) assay using Aeibe’s method [38]. The absorbance was measured at a wavelength of 240 nM using a spectrophotometer. CAT was expressed as U/min. Superoxide dismutase (SOD) assay was used to measure the superoxides [39]. The absorbance was measured at 560 nM by a microplate reader. SOD was expressed as U/mg protein.

2.11. Determination of Neurotransmitters by HPLC

High-performance liquid chromatography (HPLC) was used to quantify the serotonin and dopamine levels in brain tissues. The brain tissue excised, homogenized in phosphate buffer, and centrifuged was subjected to HPLC [40]. The sample was filtered by a 0.2 μM Teflon syringe filter and then a 20 μl volume of filtered solution was injected into the apparatus injector. The mobile phase used was a 50 mM phosphate buffer/methanol 97/3 ratio ($v/v$) with a C-18 column. Dopamine and serotonin levels were detected using a quaternary pump and UV/visible detector. The flow rate was 1.5 ml/min and the run time was 15 minutes at a wavelength of 240 nM. The quantification was performed using a standard curve of dopamine and serotonin.

2.12. Histopathology

The tissues of the kidney, liver, pancreas, and brain obtained from dissections were subjected to histopathology. The slides were made using hematoxylin and eosin (H & E) staining. The slides were examined under a light microscope at a magnification of 10× [41, 42].

2.13. Phytochemical Analysis of P. dactylifera Seeds by HPLC

The HPLC Agilent Chem station 1200 series coupled with diode array detectors (DAD, Agilent Germany) was used for the phytochemical analysis of methanolic ajwa seed extract. Reverse phase analysis was performed using the Zorbex-C8 column ($4.6\times 250$ mM, 5 μM particle size) at 20 μl injection volume [43]. Acetonitrile, methanol, water, and acetic acid in the ratio of 5 : 10 : 85 : 1 (solution A) and acetonitrile, methanol, and acetic acid in the ratio of 40 : 60 : 1 (solution B) was used as mobile phase. The gradient method was employed with 0-20 min for 0-50% B, 20-25 min for 50-100% B, and isocratic at 100% up to 30 min. The flow rate was 1 ml/min. Stock solutions used as standards included gallic acid, quercetin, myricetin, kaempferol, rutin, vanillic acid, luteolin, plumbagin, catechin, syringic acid, coumaric acid, thymoquinone, emodin, gentisic acid, caffeic acid, ferulic acid, cinnamic acid, and apigenin prepared in methanol and finally diluted to concentrations of 6.25, 12.5, 25, 50, and 100 μg/ml and standard curve were drawn. The standard solutions, mobile phase, and methanolic P. dactylifera seed extract (10 mg/ml) were degassed before analysis and filtered with a 0.45 μM membrane filter by Millipore. The analysis was done in triplicate, where each cycle was reconditioned for 10 min before the start. The results are expressed as mg/g DW. The compounds were identified by comparison of retention time and spectra with standards.

2.14. Molecular Docking

The compounds obtained from HPLC analysis of seed extracts were docked with insulin receptor and α-amylase for diabetes and dopamine, serotonin and acetylcholine for AD. The compounds obtained from HPLC phytochemical analysis included cinnamic acid, coumaric acid, ferulic acid, gallic acid, kaempferol, myricetin, quercetin, rutin, and thymoquinone. Different softwares were used for this purpose. Biovia Discovery Studio 2020 Client was used to prepare the receptor and ligand molecules for docking. MGL Tools-1.5.6 was used for docking involving Autodock Vina Tools-1.5.6 for docking receptors with different ligands [44]. PyMOL (Anaconda3) software was used to visualize docking results and interpretation. The receptors were downloaded from the protein data bank (PDB) as insulin receptor (5JYQ), α-amylase receptor (2QV4), dopamine receptor (3PBL), serotonin receptor (6BE1), and acetylcholine receptor (5CXV). The ligand structures were downloaded from PubChem as cinnamic acid (ID: 5372020), cumaric acid (ID: 637542), ferulic acid (ID: 445858), gallic acid (ID: 46780424), kaempferol (ID: 5280863), myricetin (ID: 5281672), quercetin (ID: 5280343), rutin (ID: 5280805), and thymoquinone (ID: 10281). Each receptor was docked with its respective ligand to analyze results as standard. The results showing lower binding energy and a bond length of less than 4 angstroms were considered a good interaction.

2.15. Statistical Analysis

The results were analyzed by ANOVA with Dunnet’s multiple comparison test using GraphPad Prism 7 software. The results were expressed as $\text{mean}\pm \text{SEM}$ (standard error of the mean). The significance value was $p<0.05$.

3. Results and Discussion

3.1. Blood Glucose Level

The effects of Phoenix dactylifera seeds on the blood glucose levels were measured using the Lifescan One-touch Vita™ test meter. The highest value recorded for diabetic control was 452.2 mg/dl on the 19^th day, while the highest for seed extract (400 mg/kg) was 372 mg/dl on the 4^th day. The seed extracts were effective in maintaining the blood glucose level as controlled and diabetes was minimized. The values recorded for 100, 200, and 400 mg/kg seed extract on the 19^th day were 155.8, 129.2, and 105.8 mg/dl, respectively. These values were slightly lower on the 21^st day of dissection. The results of seed extract 400 mg/kg were relatively normal (Figure 1). Previous studies have suggested that the administration of a combination of P. dactylifera seed extracts with insulin has produced good results as far as glycemic control is concerned [45]. Date seed extracts positively affect kidney and liver health and has been proven to affect hepatotoxicity positively. The literature also reported that the administration of P. dactylifera pit extracts reduces blood glucose levels and lipid fraction in streptozotocin-induced diabetic rats [46]. This study observed that the P. dactylifera seed extracts significantly declined blood glucose levels when administered over three weeks.

[figure(s) omitted; refer to PDF]

3.2. EPM Test

EPM was used to determine the anxiety-like behavior in the rats. The rats were placed in a plus-shaped maze where two sides of plus were surrounded, forming a closed arm area and two sides were exposed, forming an open arm area. The distance travelled in both arms was calculated along with the number of entries (Table 1). It was noted that the distance travelled in the open arm was greater than in the closed arm. There was a decrease in anxiety levels. The number of entries in both arms were very close in normal and disease control groups except in the positive control group, where open-arm entries were greater ($10.00\pm 1.00$) compared to closed-arm entries ($7.00\pm 1.00$). Seed extract at 400 mg/kg had $8.40\pm 1.74$ entries for the open arm and $6.40\pm 1.14$ entries for the closed arm. Seed extracts at 200 and 100 mg/kg showed a decline in entries in the open arm, i.e., $5.2\pm 0.83$ and $2.2\pm 0.83$, respectively. Similarly, the distance travelled in the closed arm was recorded as $1.587\pm 0.26$ and $0.398\pm 0.21$ m for 200 and 100 mg/kg seed extract concentrations, respectively. The distance travelled by rats of the seed extract group was seen to be greater in the open arms than in closed arms, followed by the Rivastigmine group. When the distance travelled was compared for open and closed arms, the distance travelled by seeds extract at 400 mg/kg was $3.25\pm 0.79$ m for closed arms against $3.89\pm 069$ m for open arms. Whereas for the disease control group, the distance travelled for the open arm was $2.33\pm 0.77$ m compared to $4.53\pm 0.50$ m for the closed arm. Similarly, the normal control group had $1.93\pm 0.50$ m for the closed arm and $2.59\pm 0.54$ m for the open arm (Table 1). Overall, the results showed that P. dactylifera seeds significantly decreased rat anxiety levels. EPM test is used to evaluate behavioral anxiety indices that can strongly predict and validate the screening of different plant extracts [47]. The number of entries and the distance are good and useful indexes for determining the general activity. The decreased movement towards open and elevated space attributes to fear of rats [48], which is decreased by P. dactylifera seeds as observed in this study. Increased anxiety is one of the major symptoms of AD. Thus, dates in diet help decrease anxiety in such cases. The 4% date supplementation with diet showed greater time spent in the open arm and fewer entries in the closed arm in transgenic rats than in the control group [49]. The same results are seen in this study, where the P. dactylifera seed group spent more time in open spaces than closed ones.

Table 1

Behavior study of rats treated with P. dactylifera by elevated plus maze test.

Treatment group	Number of entries in open arm	Number of entries in closed arm	Distance travelled in open arm (m)	Distance travelled in closed arm (m)
Normal control (saline 10 ml/kg)	$$3.4\pm 1.14$$	$$3.2\pm 0.836$$	$$2.59\pm 0.54$$	$$1.938\pm 0.5$$
Alzheimer’s control (saline 10 ml/kg)	$$9\pm {1.00}^{\ast \ast \ast }$$	$$9.4\pm {1.14}^{\ast \ast \ast }$$	$2.33\pm 0.77$NS	$$4.531\pm {0.5}^{\ast \ast \ast }$$
Rivastigmine (10 mg/kg)	$$10\pm {1.00}^{\ast \ast \ast }$$	$$7\pm {1.00}^{\ast \ast \ast }$$	$$3.86\pm {0.87}^{\ast \ast }$$	$$3.16\pm {0.91}^{\ast }$$
Seed extract (100 mg/kg)	$2.2\pm 0.83$NS	$1.4\pm 0.54$NS	$$1.518\pm {0.2}^{\ast }$$	$$0.398\pm {0.21}^{\ast \ast }$$
Seed extract (200 mg/kg)	$$5.2\pm {0.83}^{\ast }$$	$4.4\pm 0.54$NS	$2.45\pm 0.19$NS	$1.587\pm 0.26$NS
Seed extract (400 mg/kg)	$$8.4\pm {1.14}^{\ast \ast \ast }$$	$$6.4\pm {1.14}^{\ast \ast \ast }$$	$$3.87\pm {0.69}^{\ast \ast }$$	$$3.251\pm {0.79}^{\ast \ast }$$

Data are expressed as $\text{mean}\pm \text{SEM}$ with significant levels of ${}^{\ast \ast \ast }p<0.001$, ${}^{\ast \ast }p<0.01$, ${}^{\ast }p<0.05$, and NS are nonsignificant compared to the normal control group.

3.3. MWM Test

MWM was used to check the memory behavior of rats. The rats were left in a water pool with a platform and the time in which the rat reached that platform was calculated. The memory was assessed based on how well the rat retained the platform placement and reached there in successive trials. The results showed that memory was evaluated based on four parameters. These involve the time required to reach the platform when it is seen, i.e., visible trial; second, when the platform is underwater, i.e., hidden trial; third is time spent in the zone where the platform is placed, and fourth is the time required to reach the platform zone when released in water. For the visible trial, seed extract at 400 mg/kg group rats reached the platform in $15.26\pm 1.85$ sec compared to the Alzheimer’s control group, which had a value of $21.56\pm 1.94$ sec and showed improved memory patterns when the treatment was administered. Seed extract at 200 and 100 mg/kg showed $28.02\pm 1.18$ sec and $36.46\pm 1.18$ sec arrival at the platform, respectively, and the results were found to be significant (Table 2). In the case of the hidden trial, seed extract at the 400 mg/kg group showed a value of $20.00\pm 1.60$ sec, 200 mg/kg showed $31.54\pm 0.95$ sec, and the 100 mg/kg group showed a value of $40\pm 0.82$ sec, which proved to be efficient compared to Alzheimer’s control value $32.14\pm 1.49$ sec (Table 2). These values showed that there was quite a lot of improvement after treatment. Next, time in the close platform zone showed greater for seed extract of 400 mg/kg ($10.20\pm 1.89$ sec) compared to Alzheimer’s control ($9.76\pm 1.74$ sec). The value of positive drug control was significantly less ($0.46\pm 0.39$ sec) and even lower than normal control ($5.60\pm 1.97$ sec) (Table 2). The latency time was zero for drug control, whereas $6.64\pm 1.49$ sec for seed extract (400 mg/kg) was lower than Alzheimer’s control ($7.72\pm 1.80$ sec) (Table 2). Overall, the results showed seed extract significantly enhanced the memory of Alzheimer’s rats. The MWM test is an important parameter to check memory defects in AD by looking at the hippocampal function of the brain [50]. The administration of AlCl₃ causes loss in spatial and contextual memory, but acetic acid dose improves these effects, similar to our study [51]. The previous studies showed that dietary supplementation with 4% dates in transgenic rats improved spatial memory [49]. The dates from Oman contain a natural ferulic acid with antioxidant and anti-inflammatory properties [52]. Its use for 4 weeks to improved memory and learning behavior and inhibited astrocyte and microglia formation in mice [53]. Similar findings from this study indicated that P. dactylifera seed extract improved memory functions.

Table 2

Memory behavior analysis of rats treated with P. dactylifera by the Morris Water Maze test.

Treatment group	Time required in visible trial (sec)	Time required in hidden trial (sec)	Time spent in platform zone (sec)	Latency time to reach platform zone (sec)
Normal control (saline 10 ml/kg)	$$8.12\pm 1.73$$	$$17\pm 1.69$$	$$5.6\pm 1.97$$	$$55.3\pm 1.54$$
Alzheimer’s control (saline 10 ml/kg)	$$21.56\pm {1.94}^{\ast \ast \ast }$$	$$32.14\pm {1.49}^{\ast \ast \ast }$$	$$9.76\pm {1.74}^{\ast \ast \ast }$$	$$7.2\pm {1.80}^{\ast \ast \ast }$$
Rivastigmine (10 mg/kg)	$$15.72\pm {1.87}^{\ast \ast \ast }$$	$$19.4\pm {1.31}^{\ast }$$	$$0.46\pm {0.39}^{\ast \ast \ast }$$	$$0.0\pm 0^{\ast \ast \ast }$$
Seed extract (100 mg/kg)	$$36.46\pm {1.18}^{\ast \ast \ast }$$	$$40\pm {0.82}^{\ast \ast \ast }$$	$$27.36\pm {0.99}^{\ast \ast \ast }$$	$$24.1\pm {0.78}^{\ast \ast \ast }$$
Seed extract (200 mg/kg)	$$28.02\pm {1.18}^{\ast \ast \ast }$$	$$31.54\pm {0.95}^{\ast \ast \ast }$$	$$19.08\pm {0.76}^{\ast \ast \ast }$$	$$15.6\pm {0.74}^{\ast \ast \ast }$$
Seed extract (400 mg/kg)	$$15.26\pm {1.85}^{\ast \ast \ast }$$	$$20\pm {1.1}^{\ast \ast }$$	$$10.2\pm {1.89}^{\ast \ast \ast }$$	$$6.64\pm {1.49}^{\ast \ast \ast }$$

Data are expressed as $\text{mean}\pm \text{SEM}$ with significant levels of ${}^{\ast \ast \ast }p<0.001$, ${}^{\ast \ast }p<0.01$, and ${}^{\ast }p<0.05$ compared to the normal control group.

3.4. Serum Analysis

The blood was collected during dissection by cardiac puncture, which was centrifuged to obtain serum. The serum was subjected to various analyzes that included serum creatinine, serum ALT (alanine aminotransferase), serum AST (aspartate aminotransferase), total proteins present in serum, urea as blood urea nitrogen (BUN), and total bilirubin. Results indicated that seed extract showed normalized values of all biomarkers compared to normal control (Table 3). The Alzheimer’s control group presented slightly lower levels of compounds than the normal control, whereas the diabetes control exhibited high values. The Glibenclamide group showed values close to normal control except for blood urea nitrogen, and Rivastigmine presented a high level of all the compounds except for blood urea nitrogen. The results exhibited values of $28.32\pm 0.96$ for normal control, $36.46\pm 0.35$ for diabetes control, $20.40\pm 2.30$ for Alzheimer’s control, $21.42\pm 0.38$ for Glibenclamide, $21.00\pm 2.00$ for Rivastigmine, $9.06\pm 0.51$ for seed extract (100 mg/kg), $15.8\pm 1.30$ for seed extract (200 mg/kg), and $26.00\pm 1.81$ for seed extract (400 mg/kg) (Table 3). Overall, the results showed that P. dactylifera seeds significantly controlled the level of these compounds in the serum of rats.

Table 3

Serum biochemical parameters of control and trial groups.

Treatment group	Serum creatinine (mg/dl)	Total serum protein (G/dl)	Blood urea nitrogen (mg/dl)	Serum AST (U/l)	Serum ALT (U/l)	Total bilirubin (mg/dl)
Normal control (saline 10 ml/kg)	$$0.49\pm 0.09$$	$$5.54\pm 0.32$$	$$28.32\pm 0.96$$	$$24.68\pm 1.70$$	$$25.33\pm 0.82$$	$$0.54\pm 0.11$$
Diabetes control (saline 10 ml/kg)	$$1.002\pm {0.019}^{\ast \ast \ast }$$	$$3.3\pm {0.09}^{\ast \ast \ast }$$	$$36.46\pm {0.35}^{\ast \ast \ast }$$	$$29.54\pm {0.35}^{\ast \ast \ast }$$	$$34.48\pm {0.36}^{\ast \ast \ast }$$	$$0.71\pm {0.04}^{\ast \ast \ast }$$
Alzheimer’s control (saline 10 ml/kg)	0.30 ± 0.02${}^{\ast \ast \ast }$	$5.50\pm 0.27$NS	$20.40\pm 2.30$NS	$24.12\pm 1.46$NS	$$22.04\pm {1.48}^{\ast \ast }$$	$$0.46\pm {0.02}^{\ast \ast \ast }$$
Glibenclamide (10 mg/kg)	$0.42\pm 0.04$NS	$$5.92\pm {0.06}^{\ast }$$	$21.42\pm 0.38$NS	$26.18\pm 0.52$NS	$$22.55\pm {0.30}^{\ast \ast }$$	$$0.35\pm {0.03}^{\ast \ast \ast }$$
Rivastigmine (10 mg/kg)	$$1.84\pm {0.11}^{\ast \ast \ast }$$	$$7.76\pm {0.30}^{\ast \ast \ast }$$	$21.00\pm 2.00$NS	$$64.90\pm {2.51}^{\ast \ast \ast }$$	$$49.38\pm {1.04}^{\ast \ast \ast }$$	$$1.06\pm {0.03}^{\ast \ast \ast }$$
Seed extract (100 mg/kg)	$$0.23\pm {0.03}^{\ast \ast \ast }$$	$$3.23\pm {0.02}^{\ast \ast \ast }$$	$$9.06\pm {0.51}^{\ast \ast \ast }$$	$$18.84\pm {0.62}^{\ast \ast \ast }$$	$$20.88\pm {1.61}^{\ast \ast \ast }$$	$$0.12\pm {0.01}^{\ast \ast \ast }$$
Seed extract (200 mg/kg)	$0.52\pm 0.05$NS	$$4.23\pm {0.02}^{\ast \ast \ast }$$	$$15.8\pm {1.30}^{\ast \ast \ast }$$	$26.76\pm 0.71$NS	$$30.94\pm {1.66}^{\ast \ast \ast }$$	$$0.22\pm {0.02}^{\ast \ast \ast }$$
Seed extract (400 mg/kg)	$$0.83\pm {0.04}^{\ast \ast \ast }$$	$$6.23\pm {0.02}^{\ast \ast \ast }$$	$$25.40\pm {1.81}^{\ast \ast \ast }$$	$$34.76\pm {0.71}^{\ast \ast \ast }$$	$$40.88\pm {1.61}^{\ast \ast \ast }$$	$0.54\pm 0.03$NS

Data are expressed as $\text{mean}\pm \text{SEM}$ with significant levels of ${}^{\ast \ast \ast }p<0.001$, ${}^{\ast \ast }p<0.01$, ${}^{\ast }p<0.05$, and NS are nonsignificant compared to the normal control group where ALT and AST represent alanine aminotransferase and aspartate aminotransferase, respectively.

The serum electrolytes are liver function enzymes that control the whole body’s metabolism and indicate hepatic efficiency [54]. Ajwa dates have luteolin that helps reverse oxidative stress and restore liver functions [55]. The oral dosage of ochratoxin increased serum creatinine and urea levels, which decreased when ajwa dates were administered in rabbits [56]. The antioxidant depletion was prevented when 300 mg/kg/day of ajwa dates extract was given to lead acetate toxic albino rats for 14 days [57]. Similar results were seen in rats’ carbon tetrachloride (CCl4) toxicity [54]. The levels of AST and ALT were elevated in male Wistar rats compared to the control group by supplementation of Brassica napus [58]. These studies support our finding and the presence of serum electrolytes for the normalization of elevated levels of biomarkers.

3.5. Diabetic Markers Analysis

3.5.1. Lipase and Insulin Level Test

Pancreatic biomarker lipase was estimated in the treatment groups by extracting the serum from the blood according to the guidelines ([59] USA). The pancreas lipase levels were investigated, and the results were $147.6\pm 1.81$, $123.34\pm 1.04$, and $100.44\pm 1.40$ U/l for P. dactylifera seed extracts at 400, 200, and 100 mg/kg, respectively. Whereas normal control exhibited ($18.5\pm 1.415$ U/l), diabetic control ($112\pm 4.929$ U/l), and Glibenclamide treated group showed a mean value of $174\pm 2.12$ U/l (Table 4). Next, we investigated the pancreas insulin level of P. dactylifera seed extracts at different concentrations. We found that insulin level was not remarkably increased like lipase. Normal control showed the value of $14.57\pm 0.54$, whereas the highest value ($2.13\pm 0.02$) was shown by P. dactylifera seed extract 400 mg/kg, Glibenclamide showed a value of $0.97\pm 0.02$, and diabetes control gave $2.92\pm 0.09$ μM/ml (Table 4). In diabetes, the most common problems encountered are hyperglycemia and hypercholesterolemia [60]. In humans and vertebrates, different lipases control various functions, i.e., digestion, absorption, reconstitution of fats, and lipoprotein metabolism [61]. The previous studies suggested that in diabetes, the normal functionality of insulin-producing beta cells and lipase enzyme production is compromised, which acts as a marker to understand the damage done to the body organism by this disease. The above results show a better production of lipase enzyme in P. dactylifera seed extracts compared with diabetic control. However, insulin production does not affect seed extracts much, which explains that they are not very efficient in raising insulin levels. Rather, they cope with the signs and symptoms caused by diabetes mellitus.

Table 4

The effect of P. dactylifera on the levels of lipase and insulin.

Treatment group	Lipase (U/l)	Insulin (μM/ml)
Normal control (saline 10 ml/kg)	$$18.54\pm 1.41$$	$$14.47\pm 0.54$$
Diabetes control (saline 10 ml/kg)	$$109.4\pm {1.14}^{\ast \ast \ast }$$	$$2.92\pm {0.09}^{\ast \ast \ast }$$
Glibenclamide (10 mg/kg)	$$174\pm {2.12}^{\ast \ast \ast }$$	$$0.97\pm {0.02}^{\ast \ast \ast }$$
Seed extract (100 mg/kg)	$$100.44\pm {1.40}^{\ast \ast \ast }$$	$$0.54\pm {0.05}^{\ast \ast \ast }$$
Seed extract (200 mg/kg)	$$123.34\pm {1.04}^{\ast \ast \ast }$$	$$1.39\pm {0.10}^{\ast \ast \ast }$$
Seed extract (400 mg/kg)	$$147.6\pm {1.81}^{\ast \ast \ast }$$	$$2.13\pm {0.02}^{\ast \ast \ast }$$

Data are expressed as $\text{mean}\pm \text{SEM}$ with significant levels of ${}^{\ast \ast \ast }p<0.001$ compared to normal control.

3.5.2. α-Amylase Activity

The enzyme α-amylase is responsible for the hydrolysis of starch and other disaccharides into simple sugars and is involved in the breakdown of long-chain carbohydrates. In the human body, this enzyme is most excessively present in pancreatic juice and saliva, each having its isoforms, which can be differentiated in isoelectric focusing. It has been concluded that salivary amylase evolved from pancreatic amylase. The amylase test determines whether one person has a pancreatic disorder or not by measuring the level of amylase in the body. Seed extract groups of different concentrations, such as 400, 200, and 100 mg/kg, exhibited a percentage decrease in amylase as $83.87\pm 2.66$%, $50.74\pm 1.80$%, and $33.99\pm 0.14$%, respectively (Figure 2). The results showed the highest values for activity in Glibenclamide control and P. dactylifera seed extracts (400 mg/kg) for pancreatic amylase. One of the strategies to control the levels of blood glucose in chronic patients is to retard the hydrolysis of carbohydrates by controlling the α-amylase and α-glucosidase activity. These enzymes are considered promising targets for managing diabetes [62]. In the current study, pancreatic and liver amylases were tested and the results are significant compared to the Glibenclamide control. Pancreatic amylase gives a higher inhibition control than liver amylase [63]. Hence, it can be concluded that P. dactylifera seed extracts have a good effect on pancreatic cells compared to liver cells.

[figure(s) omitted; refer to PDF]

3.6. Alzheimer’s Marker Analysis

3.6.1. Determination of Acetylcholine Levels

The brain contains neurotransmitters and neuromodulators such as acetylcholine, ensuring efficient nerve impulse propagation and brain functioning. The results indicated that the seed extract (400 mg/kg) group showed a value of $56.73\pm 0.04$% compared to low levels of Alzheimer’s control group of $7.80\pm 0.05$% for acetylcholine. The normal control values were $51.77\pm 0.03$%, whereas Rivastigmine showed $72.34\pm 0.03$% for acetylcholine. The 200 mg/kg seed extract showed $43.82\pm 0.01$%, while 100 mg/kg exhibited $33.04\pm 0.01$% for acetylcholine (Figure 3). The results indicated that P. dactylifera seeds were significantly effective in the production of these compounds.

[figure(s) omitted; refer to PDF]

Acetylcholine is an important neurotransmitter that is involved in memory and learning processes. A change in cholinergic activities causes significant effects in AD [63]. The ajwa dates provide a neuroprotective effect due to certain polyphenols like flavonoids, sterols, and ascorbic acid [64]. Ganoderma lucidum is reported to have phenols such as quercetin, catechins, and rutin that provide choline esterase inhibition activity [65] which are also reported in ajwa dates. Rutin hydrate, among many polyphenols, accounted for the acetylcholine activity in Bouvardia ternifolia [66]. Similarly, Atriplex laciniata crude extracts showed acetylcholine inhibitor activity that ranged from $64.36\pm 0.61$% to $88.31\pm 0.57$% [67]. Terpinolene, a component of Pinus essential oils, showed inhibition for acetylcholine with IC₅₀ values of 156.4 μg/ml [68]. Similarly, in our results, ajwa seeds showed choline esterase inhibitory activity of 56.73%. In this study, P. dactylifera seeds alleviated the level of choline in the brain that was depleted due to disease.

3.7. Determination of Antioxidant Enzymes

Oxidation reactions in the body produce free radicals, leading to chain reactions that may damage the organism or the cell. Antioxidants counter the action of these free radicals and save the cells from destruction.

3.7.1. Kidney Samples

In diabetes, the blood vessels become damaged and kidney-filtering units cannot function properly. As time passes, the blood vessels narrow and clog in decreased function. The ROS (reactive oxygen scavenging) capacity of antioxidants helps maintain the body’s normal homeostasis. Antioxidant properties of P. dactylifera seed extracts were studied and their effects were tested on different control groups in Sprague Dawley rats. The results explain the highest value for total protein content was shown by Glibenclamide control, i.e., $11.68\pm 0.6$ μg/mg tissue. In contrast, the values for seed extract (400 mg/kg) are $3.16\pm 0.03$ μg/mg tissue which is somehow resembling the protein contents represented by diabetic control, i.e., $3.24\pm 0.03$ μg/mg tissue (Table 5). POD levels were the highest for Glibenclamide control and lowest for seed extract (400 mg/kg), i.e., $3.30\pm 0.68$ U/min and $0.04\pm 0.01$ U/min, respectively (Table 5). GSH assay and levels of tested samples carried out quantifying GSH and Glibenclamide control ($0.165\pm 0.02$ mM/g tissue) is presented in Table 5. Results indicated that seed extract (400 mg/kg) showed a significant value of $0.10\pm 0.02$ mM/g tissue, whereas 200 and 100 mg/kg concentration exhibited $0.03\pm 0.06$ and $0.01\pm 0.05$ mM/g tissue values, respectively (Table 5). TBARS antioxidant value was highest for Glibenclamide control and lowest for diabetic control, while the seed extract (400 mg/kg) showed a value of $0.020\pm 0.14$ nM/min/mg tissue (Table 5). The highest catalase activity was shown by seed extract of 400 mg/kg concentration ($42.76\pm 0.003$ U/min). While the reference group was normal, the control showed a value of $15.92\pm 0.04$ U/min (Table 5). SOD activity was highest for seed extract (400 mg/kg) $18.32\pm 0.003$ U/mg protein, while the Glibenclamide showed a value of $5.52\pm 0.42$ U/mg and the results were significant (Table 5). The antioxidant property of any natural or synthetic product is a complex mechanism; hence, a multidimensional approach is utilized to sort out a statistical value [69].

Table 5

Effect of antioxidant enzymes on kidney, liver, pancreas, and brain of control and trial group rats.

Tissue	Treatment group	Total protein (μg/mg tissue)	POD (U/min)	GSH (mM/g tissue)	TBARS (nM/min/mg tissue)	CAT (U/min)	SOD (U/mg protein)
Kidney	Normal control (saline 10 ml/kg)	$$4.81\pm 0.04$$	$$0.08\pm 0.27$$	$$0.15\pm 0.06$$	$$0.02\pm 0.002$$	$$15.92\pm 0.04$$	$$5.34\pm 0.04$$
	Diabetes control (saline 10 ml/kg)	$$3.24\pm {0.03}^{\ast \ast \ast }$$	$0.11\pm 0.06$NS	$$0.09\pm {0.29}^{\ast \ast \ast }$$	$$0.001\pm {0.32}^{\ast \ast \ast \ast \ast }$$	$$6.76\pm {0.04}^{\ast \ast \ast }$$	$$1.34\pm {0.03}^{\ast \ast }$$
	Glibenclamide (10 mg/kg)	$$10.77\pm {0.69}^{\ast \ast \ast }$$	$$00.03\pm {0.008}^{\ast \ast }$$	$0.165\pm 0.02$NS	$$0.006\pm {0.002}^{\ast \ast \ast }$$	$$9.92\pm {0.55}^{\ast \ast \ast }$$	$5.52\pm 0.42$NS
	Seed extract (100 mg/kg)	$$0.95\pm {0.04}^{\ast \ast \ast }$$	$$0.005\pm {0.01}^{\ast \ast \ast }$$	$$0.01\pm {0.05}^{\ast \ast \ast }$$	$$0.0006\pm 0.0005\pm {}^{\ast \ast \ast }$$	$$2.93\pm {0.05}^{\ast \ast \ast }$$	$$1.50\pm {0.003}^{\ast }$$
	Seed extract (200 mg/kg)	$$1.68\pm {0.01}^{\ast \ast \ast }$$	$$0.01\pm {0.01}^{\ast \ast \ast }$$	$$0.03\pm {0.06}^{\ast \ast \ast }$$	$$0.003\pm {0.0007}^{\ast \ast \ast }$$	$17.20\pm 0.02$NS	$6.44\pm 0.004$NS
	Seed extract (400 mg/kg)	$$3.14\pm {0.03}^{\ast \ast \ast }$$	$$0.04\pm {0.01}^{\ast }$$	$$0.10\pm {0.02}^{\ast \ast \ast }$$	$$0.01\pm {0.05}^{\ast \ast \ast }$$	$$42.76\pm {0.003}^{\ast \ast \ast }$$	$$18.32\pm {0.003}^{\ast \ast \ast }$$
Liver	Normal control (saline 10 ml/kg)	$$2.13\pm 0.16$$	$$0.03\pm 0.12$$	$$0.06\pm 0.01$$	$$0.007\pm 0.03$$	$$16.92\pm 0.04$$	$$6.12\pm 0.04$$
	Diabetes control (saline 10 ml/kg)	$$3.42\pm {0.03}^{\ast \ast }$$	$$0.11\pm {0.003}^{\ast \ast \ast }$$	$$0.11\pm {0.05}^{\ast \ast \ast }$$	$$0.01\pm {0.01}^{\ast \ast \ast }$$	$$9.8\pm {0.41}^{\ast \ast \ast }$$	$$3.32\pm {0.16}^{\ast \ast \ast }$$
	Glibenclamide (10 mg/kg)	$$3.54\pm {0.29}^{\ast \ast }$$	$0.04\pm 0.004$NS	$$0.04\pm {0.002}^{\ast \ast }$$	$0.006\pm 0.002$NS	$$13.19\pm {0.60}^{\ast \ast }$$	$6.008\pm 0.23$NS
	Seed extract (100 mg/kg)	$$0.008\pm {0.004}^{\ast \ast \ast }$$	$$0.0003\pm {0.006}^{\ast \ast \ast }$$	$$0.001\pm {0.01}^{\ast \ast \ast }$$	$$0.0001\pm {0.09}^{\ast \ast \ast }$$	$$1.43\pm {0.004}^{\ast \ast \ast }$$	$$0.08\pm {0.001}^{\ast \ast \ast }$$
	Seed extract (200 mg/kg)	$$0.37\pm {0.008}^{\ast \ast \ast }$$	$$0.002\pm {0.02}^{\ast \ast \ast }$$	$$0.009\pm {0.04}^{\ast \ast \ast }$$	$$0.001\pm {0.008}^{\ast \ast \ast }$$	$$9.79\pm {0.004}^{\ast \ast \ast }$$	$$1.33\pm {0.004}^{\ast \ast \ast }$$
	Seed extract (400 mg/kg)	$$1.02\pm {0.02}^{\ast \ast \ast }$$	$$0.01\pm {0.04}^{\ast \ast \ast }$$	$$0.03\pm {0.03}^{\ast \ast \ast }$$	$$0.003\pm {0.005}^{\ast \ast }$$	$$38.68\pm {0.004}^{\ast \ast \ast }$$	$5.94\pm 0.003$NS
Pancreas	Normal control (saline 10 ml//kg)	$$1.43\pm 0.04$$	$$0.03\pm 0.21$$	$$0.04\pm 0.03$$	$$0.007\pm 0.02$$	$$8.8\pm 0.51$$	$$3.09\pm 0.04$$
	Diabetes control (saline 10 ml/kg)	$1.37\pm 0.01$NS	$$0.001\pm {0.004}^{\ast \ast \ast }$$	$0.04\pm 0.004$NS	$0.01\pm 0.03$NS	$$1.82\pm {0.04}^{\ast \ast \ast }$$	$$3.09\pm {0.04}^{\ast \ast \ast }$$
	Glibenclamide (10 mg/kg)	$1.24\pm 0.12$NS	$$0.07\pm {0.008}^{\ast }$$	$0.03\pm 0.008$NS	$0.006\pm 0.001$NS	$$6.73\pm {0.33}^{\ast \ast \ast }$$	$2.92\pm 0.15$NS
	Seed extract (100 mg/kg)	$$0.57\pm {0.008}^{\ast \ast \ast }$$	$$0.0002\pm {0.08}^{\ast \ast \ast }$$	$$0.006\pm {0.04}^{\ast \ast \ast }$$	$$0.0003\pm {0.01}^{\ast \ast \ast }$$	$$0.25\pm {0.007}^{\ast \ast \ast }$$	$$0.11\pm {0.0004}^{\ast \ast \ast }$$
	Seed extract (200 mg/kg)	$$1.04\pm {0.02}^{\ast }$$	$$0.002\pm {0.02}^{\ast \ast \ast }$$	$$0.01\pm {0.04}^{\ast \ast \ast }$$	$$0.0009\pm {0.01}^{\ast \ast \ast }$$	$$2.13\pm {0.01}^{\ast \ast \ast }$$	$$0.79\pm {0.0004}^{\ast \ast \ast }$$
	Seed extract (400 mg/kg)	$$1.99\pm {0.05}^{\ast \ast \ast }$$	$$0.01\pm {0.004}^{\ast \ast \ast }$$	$$0.06\pm {0.004}^{\ast \ast \ast }$$	$$0.007\pm {0.02}^{\ast }$$	$9.23\pm 0.001$NS	$3.32\pm 0.002$NS
Brain	Normal control (saline 10 ml/kg)	$$2.65\pm 0.003$$	$$0.08\pm 0.17$$	$$0.08\pm 0.01$$	$$0.007\pm 0.005$$	$$4.40\pm 0.31$$	$$1.20\pm 0.31$$
	Alzheimer’s control (saline 10 m//kg)	$$6.42\pm {0.04}^{\ast \ast \ast }$$	$$0.18\pm {0.23}^{\ast \ast \ast }$$	$$0.21\pm {0.03}^{\ast \ast \ast }$$	$$0.01\pm {0.02}^{\ast \ast \ast }$$	$$2.50\pm {0.49}^{\ast \ast \ast }$$	$$0.50\pm {0.31}^{\ast \ast }$$
	Rivastigmine (10 mg/kg)	$2.88\pm 0.1$NS	$0.07\pm 0.16$NS	$0.09\pm 0.05$NS	$0.007\pm 0.02$NS	$3.70\pm 0.31$NS	$1.02\pm 0.42$NS
	Seed extract (100 mg/kg)	$$0.062\pm {0.01}^{\ast \ast \ast }$$	$$0.02\pm {0.03}^{\ast }$$	$$0.01\pm {0.08}^{\ast \ast \ast }$$	$$0.0001\pm {0.03}^{\ast \ast \ast }$$	$$0.11\pm {0.003}^{\ast \ast \ast }$$	$$0.07\pm {0.003}^{\ast \ast \ast }$$
	Seed extract (200 mg/kg)	$$1.12\pm {0.01}^{\ast \ast \ast }$$	$0.04\pm 0.01$NS	$$0.02\pm {0.07}^{\ast \ast \ast }$$	$$0.001\pm {0.008}^{\ast \ast }$$	$$0.85\pm {0.004}^{\ast \ast \ast }$$	$$0.29\pm {0.0001}^{\ast \ast \ast }$$
	Seed extract (400 mg/kg)	$2.43\pm 0.02$NS	$$0.15\pm {0.02}^{\ast \ast }$$	$0.07\pm 0.03$NS	$0.007\pm 0.02$NS	$3.75\pm 0.01$NS	$1.14\pm 0.0004$NS

Data are expressed as $\text{mean}\pm \text{SEM}$ with significant levels of ${}^{\ast \ast \ast }p<0.001$, ${}^{\ast \ast }p<0.01$, ${}^{\ast }p<0.05$, and NS are nonsignificant compared to the normal control group. POD, GSH, CAT, SOD, and TBARS represent peroxidases, glutathione, catalase, superoxide dismutase, and thiobarbituric acid reactive substance, respectively.

3.7.2. Liver Samples

The liver acts as a natural stabilizer, disinfecting and cleansing the body and helping to neutralize any free radicals formed inside the body. The tissue homogenate from the liver in terms of total protein value for Glibenclamide ($3.54\pm 0.29$ μg/mg tissue) and seed extract (400 mg/kg) showed a resembling value of $1.02\pm 0.02$ μg/mg tissue as compared to the reference normal control group which was $2.13\pm 0.16$ μg/mg tissue (Table 5). On the other hand, POD presented the lowest value for seed extract of 400 mg/kg ($0.01\pm 0.02$ U/min) and the highest for diabetic control at $0.11\pm 0.003$ U/min (Table 5). Besides, GSH and TBARS followed the pattern and contributed the highest value for Glibenclamide control. GHS for P. dactylifera seed extract of 400 mg/kg ($0.03\pm 0.03$ mM/g tissue), 200 mg/kg ($0.009\pm 0.04$ mM/g tissue), and 100 mg/kg ($0.001\pm 0.01$ mM/g tissue). Similarly, P. dactylifera seed extract of 400, 200, and 100 mg/kg showed values of $0.003\pm 0.005$, $0.001\pm 0.008$, and $0.0001\pm 0.09$ nM/g tissue for TBARS, respectively (Table 5). CAT analysis presented the highest value for seed extract (400 mg/kg) and the lowest for diabetic control. SOD values were $5.94\pm 0.003$ U/mg for 400 mg/kg extract and diabetic control showed $3.32\pm 0.16$ U/mg protein. Seed extract at 200 and 100 mg/kg exhibited declining results with values of $1.33\pm 0.00$ and $0.08\pm 0.001$ U/mg protein, respectively (Table 5). In a previous study, both the oxidative and nonoxidative stress mechanisms were not functional, which can be elaborated by the highly harmful effects of increased oxidative stress [70].

3.7.3. Pancreas Samples

Various markers, including total protein content, SOD, CAT, POD, TBARS, and GSH, tested antioxidant levels in the pancreas. These assays gave an idea about the health of the pancreas. They explained the effectiveness of the P. dactylifera seeds as an antidiabetic agent in the pharmaceutical industry. Results of total protein content in pancreas homogenate was found to be $1.99\pm 0.05$ μg/mg of tissue, POD ($0.01\pm 0.004$ U/min) GSH ($0.06\pm 0.004$ mM/g tissue), and TBARS ($0.007\pm 0.02$ nM/min/mg tissue) for seed extract of 400 mg/kg (Table 5). CAT activity of homogenate pancreas tissue of Sprague Dawley rats in different groups exhibited a higher level of CAT activity at $9.23\pm 0.001$ U/min. The 200 and 100 mg/kg seed extract showed CAT levels of $2.13\pm 0.01$ and $0.25\pm 0.007$ U/min, respectively. Similarly, SOD was $3.32\pm 0.002$, $0.79\pm 0.0004$, and $0.11\pm 0.0004$ at different dose levels (Table 5). An increase in SOD activity was previously documented due to its induction by increased production of superoxides [71].

3.7.4. Brain Samples

Next, we investigated the total protein, POD, GSH, TBARS, CAT, and SOD activity in rat’s brains against seed extracts. Compared with the normal control group, moderate activity restored these antioxidant enzymes. The results are presented in Table 5 and the values for positive control were quite close to normal control. Alzheimer’s control showed high values of protein, POD, GSH, and TBARS but low values for CAT and SOD compared to the normal control group. The POD level and SOD activity of seed extracts (400 mg/kg) was higher than the normal control value as $0.15\pm 0.02$ U/min versus $0.08\pm 0.17$ U/min for POD and $1.25\pm 0.0005$ U/mg versus $1.20\pm 0.31$ U/mg or SOD, respectively (Table 5). The oxidative stress is mediated due to free radicals, so it is necessary to account for antioxidant enzymes that serve as the first line of defence against radicals. CAT, GSH, and TBARS enzymes all account for neuron protection in oxidative stress [72]. GSH levels are known for disrupting neurons in neurodegenerative diseases [73]. In our study, GSH increased in Alzheimer’s control, but ajwa seeds lowered the level taking it close to normal control. Our previous study reported that the SOD and CAT activities were very low in Alzheimer’s rats [74]. Catalase and GSH levels are reported in the literature after AlCl₃ treatment in Alzheimer’s rats [75]. However, in our current study, ajwa seeds helped bring the level of antioxidant enzymes to a normal range.

3.8. Determination of Neurotransmitters

Neurotransmitters are essential carriers in the brain that are involved in brain functioning and coordination. The level of neurotransmitters (dopamine and serotonin) was determined via HPLC as they were linked to AD complications in previous studies [76]. The results showed that dopamine levels increased when seed extract (400 mg/kg) or Rivastigmine was given with values of $0.18\pm 1.76$ tissue and $0.74\pm 1.63$ μg/mg of tissue, respectively, as compared to normal control $0.08\pm 0.68$ μg/mg of tissue. In comparison, Alzheimer’s control group, none of the neurotransmitters was detected (Figure 4). Serotonin levels were higher for seed extract (400 mg/kg) and Rivastigmine as $0.56\pm 1.57$ and $0.94\pm 1.46$ μg/mg of tissue, respectively, as compared to $0.19\pm 1.49$ μg/mg of tissue of normal control group (Figure 4). Seed extracts group of 200 and 100 mg/kg showed reduced levels of dopamine and serotonin when compared with control groups. Overall results showed that P. dactylifera seeds help maintain neurotransmitter levels in rat’s brains which were nearly absent in the diseased rats. However, the levels of Alzheimer’s control were very low compared to normal control, which explains why these compounds were not detected in our experiment due to the nearly negligible amount. P. dactylifera seeds help normalize the level of neurotransmitters which are negligible in the disease control group.

[figure(s) omitted; refer to PDF]

Dopamine and serotonin are catecholamines responsible for brain nerve pathways and play an essential function in cognitive learning and memory functions [77]. Serotonin decreases in Alzheimer’s patients, which is consistent with cognitive processing [78]. It is reported that ajwa date pits administered for two weeks are involved in the maximal increase in the level of neurotransmitters such as dopamine [79]. In other reports, P. dactylifera is effective in managing brain ischemia in rats due to antioxidant effects [80]. The level of dopamine increased to 876.25 pg/mg brain tissue from 30.53 pg/mg in the striatum part of Parkinson’s affected rat’s brain after 12 weeks of grafting with TH gene-producing muscle cells [81]. Tooth loss also causes AD due to emotions and cognition in elders, whereas voluntary wheel running is said to fight the disease. HPLC analysis of the brain of rats suffering from tooth loss showed dopamine levels of $26.48\pm 6.67$ fmol against normal rat’s $55.02\pm 9.05$ fmol. After wheel running for one week, the level rose to $50.01\pm 10.52$ fmol and after four weeks dopamine level was $52.34\pm 12.54$ fmol which was quite close to normal control and indicated wheel running exercise increased dopamine levels [82]. In literature, other plants are also reported for their involvement in brain neurotransmitters by ethanolic extract of Tylophora indica, increased dopamine levels of $30.655\pm 0.55\times {10}^3$ units/g in alcohol-toxic albino rats from an initial level of $3.283\pm 0.172\times {10}^3$ units/g [83]. Likewise, Ginkgo biloba extract administered for 14 days in rats did not affect serotonin levels, but a significant effect was seen on dopamine levels [84]. A study on targeted neurotransmitters profiling showed the amount of serotonin and dopamine in Alzheimer’s rat brains $0.886\pm 0.087$ and $5.353\pm 1.016$ ng/mg, respectively, as compared to normal control $1.551\pm 0.262$ and $7.225\pm 0.873$, respectively [85]. Treating Alzheimer’s rats with Hedera nepalensis also increased serotonin and dopamine neurotransmitters [29].

3.9. Histopathology Analysis

The tissues of the kidney, liver, pancreas, and brain were analyzed under a light microscope at a magnification of 10×. Overall comparison showed that in disease group major pathological irregularities were observed as compared to normal control group in the form of shrinkage and swelling cells. However, rats pretreated with extracts at different concentrations revealed significant improvements and microscopic images showed the normal histological structure as presented in Figures 5–8.

[figure(s) omitted; refer to PDF]

3.9.1. Kidney Samples

The kidney tissue slides were observed by H & E staining under a microscope for histopathology. Results indicated that in normal control, a clear and distinct Bowman’s capsules and glomerulus were examined and no overlapping tubules were seen. In diabetes control, overlapping tubules were noted with the absence of the clear Bowman’s capsule and a clear glomerulus was spotted. In the Glibenclamide group, disrupted Bowman’s capsule with a clear glomerulus and overlapping tubules were observed. In the 100 mg/kg seed extract group, no clear and distinct Bowman’s capsule and glomerulus were noticed with overlapping tubules. The 200 mg/kg seed extract group exhibited some clear and distinct Bowman’s capsules and glomerulus with overlapping tubules. In contrast, 400 mg/kg extract concentration showed clear and distinct Bowman’s capsule and glomerulus with slight overlapping of tubules (Figure 5). The P. dactylifera seed extracts showed an improved structure of nephrons.

3.9.2. Liver Samples

Histopathology of normal liver tissues revealed no overlapping and visible patterns with clear sinusoids and peripheral cells. In diabetes control, no visible pattern, densely populated cells, unclear sinusoids, and prominent immune cells were noticed. Densely populated cells with no discernible pattern, sinusoids, and prominent immune cells were observed in the Glibenclamide group. Immune and peripheral cells were poorly observed in the seed extract group at 100 and 200 mg/kg. On the other side, in the seed extract group at 400 mg/kg, no visible pattern was examined, and sinusoids, immune cells and peripheral cells were seen (Figure 6). Treatment of P. dactylifera seeds showed restoration of hepatocytes structure compared to diseased ones.

3.9.3. Pancreas Samples

Next, we examined the histopathology of pancreatic tissues. Clear Islets of Langerhans, ducts and patterns were seen in the normal control. There were no Islets of Langerhans, visible ducts, or patterns in diabetes control. Degraded Islets of Langerhans and visible ducts and patterns were observed in the Glibenclamide group. Few visible ducts and patterns were observed in seed extract groups at 200 and 400 mg/kg degraded Islets of Langerhans. In contrast, no visible ducts and patterns were observed in 100 mg/kg seed extract highly degraded Islets of Langerhans (Figure 7). Seed extract helped improve the structure of pancreatic cells.

3.9.4. Brain Samples

Brain tissues were stained with H & E and examined under a microscope for histopathology. Uniform cells and visible cell boundaries were observed in the normal group. Alzheimer’s disease control cells were deformed and loosely packed. While deformed and closely packed cells were found in the Rivastigmine group. Seed extract (100 mg/kg) exhibited highly deformed and loosely packed cells, whereas at 200 mg/kg, deformed and loosely packed cells were observed. The less deformed and loosely packed cells were observed at a seed extract concentration of 400 mg/kg (Figure 8). The neuron pathology was restored owing to P. dactylifera extract treatment.

3.10. Phytochemical Analysis of P. dactylifera Seeds by HPLC

The seeds of P. dactylifera were subjected to HPLC-DAD analysis to identify flavonoids. The retention time and spectra provide bases for identifying these flavonoids found in seeds. Cinnamic acid, cumaric acid, ferulic acid, gallic acid, kaempferol, myricetin, quercetin, rutin, and thymoquinone were present. The peak for kaempferol and myricetin in P. dactylifera seeds was the same as the standard. The retention time of identified P. dactylifera compound (Table S1). Further, docking analysis was performed on the compounds that were discovered. Flavonoids in various fruits and vegetables have a characteristic benzo-4-pyrone ring. There are approximately 9000 flavonoids reported. Flavonoids, which have many properties such as anti-inflammatory, antiageing, antiallergic, and radical scavenging activity, can help fit various diseases when consumed regularly. It is beneficial in treating cardiovascular, neurodegenerative, and diabetes diseases [86]. A previous study on ajwa dates found quercetin and rutin concentrations of $1.219\pm 0.071$ and $0.853\pm 0.049$ mg/100 mg DW, respectively [87].

3.11. Docking Analysis

Docking was performed with Autodock Vina software and the results were interpreted with PyMOL. The molecules identified by HPLC from seed extract were docked with insulin receptor and α-amylase for diabetes. Dopamine, serotonin, and acetylcholine receptors were docked for AD. P. dactylifera HPLC analysis yielded the following compounds: cinnamic acid, cumaric acid, ferulic acid, gallic acid, kaempferol, myricetin, quercetin, rutin, and thymoquinone. The lower binding energies indicated stable interactions and a bond length less than 4 Å indicated an excellent and stable interaction. The tight packing of ligands and receptors is maintained by hydrogen bonding and van der Waals forces [88]. Hydrogen bonding is shown between 2.8 Å and 3.4 Å and van der Waals between 3.8 Å and 4.2 Å so 4 Å shows all the measurements. All interactions between receptor molecules and their ligands were treated as standard interactions.

Insulin receptor showed an energy level of -5.5 kcal/mol with insulin ligands. In contrast, other ligands have lower energy except for cinnamic acid, cumaric acid, ferulic acid, and thymoquinone, which had high energy (Table S1). The bond lengths also show a strong interaction and predict the activation of the downstream cascade in vivo. The α-amylase receptor showed an energy of -5.1 kcal/mol with the α-amylase ligand, while other ligands have lower energies (Table S2). The examined bond lengths and strong binding energies indicate a strong cellular cascade. The dopamine receptor showed an energy of -5.9 kcal/mol with dopamine ligand, which is the same for cinnamic acid and lower for other compounds, which showed a stable interaction (Table S3). Serotonin receptors showed an energy of -5.1 kcal/mol with serotonin ligand, while other ligands have lower energy except for cinnamic acid, cumaric acid, and thymoquinone, which had high energies (Table S2). Acetylcholine receptor an showed an energy of -4.1 kcal/mol with acetylcholine ligand and other ligands showed stable interaction with lower energies (Table S3). All the brain receptors showed strong energies and good interaction bonding that predict a strong cellular response activation if these ligands are used in place of the original ligand in vivo.

All the compounds showing interactions were within a bond length of 4 Å, indicating good results. Insulin showed the best results as it interacted with low energy and bond length with all the compounds. The binding of these compounds with receptors shall initiate the downstream pathway similar to one with the respective ligand. The results show that the low-energy compounds can be used as substitute for the original ligands and act on their behalf. The strong binding energy shows that these ligands shall bind with their respective cell surface receptors effectively and initiate a strong downstream cascade. The docking interactions of diabetic and Alzheimer’s markers are presented in Figure 9. In contrast, the docking analysis of insulin receptor interaction with flavonoids includes cinnamic acid, cumaric acid, ferulic acid, gallic acid, kaempferol, myricetin, quercetin, rutin, and thymoquinone (Figure S1). Similarly, α-amylase interaction with flavonoid compounds (cinnamic acid, cumaric acid, ferulic acid, kaempferol, myricetin, and thymoquinone) (Figure S2), and dopamine interaction with cinnamic acid, ferulic acid, kaempferol, and myricetin showed binding activity (Figure S3).

[figure(s) omitted; refer to PDF]

4. Conclusions

Phoenix dactylifera seeds exhibited promising results in improving memory patterns. Antioxidant enzymes and neurotransmitter levels in brain tissues were also enhanced. Histopathological studies provide evidence of tissue neuroprotection. Additionally, the docking studies identified potential interaction targets between the bioactive compounds from P. dactylifera seeds and Alzheimer’s proteins. However, this study provides only the baseline information and further studies are needed to reveal the molecular mechanism of Alzheimer’s disease treatment using P. dactylifera seeds.

Acknowledgments

We are thankful to Michel De Waard and the French Agence Nationale de la Recherche and the Région Pays de la Loire for financial support under grant number 2020 07132. Moreover, we also acknowledged the University of Gujrat and National University of Medical Sciences, Pakistan for providing facilities for this research.

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