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Pterostilbene (trans-3,5-dimethoxy-4-hydroxystilbene) is a chemical classified as a stilbene, that is produced naturally by a variety of plants, predominantly found in blueberries, several types of grapes, and tree wood. These plants secrete stilbenes in response to environmental challenges such as microbial infection or excessive ultraviolet exposure [1]. One of the best characterized stilbenes, resveratrol, is known to be an antioxidant, antiaging compound, and anti-inflammatory agent. Pterostilbene is structurally similar to resveratrol; however, pterostilbene exhibits better bioavailability due to the presence of two methoxy groups, which leads to increased lipophilic and oral absorption, as well as the potential for higher cellular uptake and a longer half-life than resveratrol [2]. In animal studies, pterostilbene was shown to have 80% bioavailability compared with 20% for resveratrol making it potentially advantageous as a therapeutic agent [3]. Research regarding pterostilbene attracted more attention, when it was shown to have better antiproliferative effects in cultured cells than resveratrol. Subsequently, the anti-inflammatory, -obesity, and -oxidant properties were reported. More recently, clinical trials have been conducted to evaluate the potential of pterostilbene in treating or preventing cardiac diseases [4]. Thus, pterostilbene may have numerous preventive/therapeutic properties as well as market prospects in a variety of human diseases including neurological, cardiovascular, metabolic, cancerous, and skin disorders.
In general, autophagy is a mechanism of cellular self-consumption for the recycling of intracellular “cargo” such as damaged proteins and organelles. Basal autophagy helps maintain homeostasis, while additional autophagy is induced in response to many different forms of stress including nutrient, oxygen and growth factor deprivation, and chemotherapeutics, in turn serving as a cell-survival mechanism [5]. Autophagic defects have been implicated in various diseases and health states, including neurodegeneration, aging, infectious disease, skin disease, and cancer [6]. However, the role of autophagy in human diseases is complicated and controversial. For example; in cancer research, autophagy could act as a cytoprotective mechanism by degrading the cytotoxic substances for energy reuse. Nonetheless, when the damage is irreversible and beyond the level that cells can endure, autophagy may also play a role as death executioner [6]. Our previous reports showed that combined treatment with irradiation and chemotherapeutic agents induced both autophagy and apoptosis in several cancerous cells, where autophagy played a more...