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Journal of Wuhan University of Technology-Mater. Sci. Ed. Sept. 2011 955
DOI 10.1007/s11595-011-0344-8
Anti-inammatory Effects and Mechanisms of Usnic Acid
HUANG Zhijun1, 2, ZHENG Guohua3, TAOJunyan 3, RUAN Jinlan1*
(1.College of Pharmacy, Tongji Medical Center, Huazhong University of Science and Technology, Wuhan 430030, China; 2.School of Chemical Engineering, Wuhan University of Technology, Wuhan 430070, China; 3.School of Pharmacy, Hubei University of
Traditional Chinese Medicine, Wuhan 430065, China)
Abstract: The anti-inammatory effect and mechanism of Usnic acid (UA) were explored on lipopolysaccharide (LPS)-stimulated RAW264.7 cell line. The effects of UA on pro-inammatory cytokines including tumor necrosis factor-alfa (TNF-), interleukin-6 (IL-6) and interleukin-1 beta (IL-1), pro-inflammatory mediators such as nitric oxide (NO), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) were studied by sandwich ELISA, real-time PCR and western blot analyses. Similarly, the effect of UA on anti-inammatory cytokine interleukin-10 (IL-10) and anti-inammatory mediator heme oxygenase-1 (HO-1) were also studied following the same methods. Furthermore, nuclear factor-B (NF-B) was assayed by immunocytochemistry. The results showed that UA has anti-inammatory effect by down-regulatinng iNOS, COX-2, IL-1, IL-6 and TNF-, COX-2 gene expression through the suppression of NF-B activation and increasing anti-inammatory cytokine IL-10 and anti-inammatory mediator HO-1 production.
Key words: usnic acid; anti-inammation; western blot analyses; immunocytochemistry
1 Introduction
Usnic acid (UA) is well-known as an antibiotic, endowed with several biological and physiological activities including antiviral, antibiotic and anti-inflammatory[1,2]. However, the anti-inflammatory activity and mechanism of UA have rarely been researched further . Hence studying the anti-inammatory mechanism of UA was undertaken as an objective of the present study.
Inflammation is a multiple process, mediated by activated inammatory factors or immune cells. During its course, macrophages and monocytes usually play crucial roles in eliciting response cascade in the acute phase of inflammation. After being stimulated, they produce a number of chemokines and enzymes, such as TNF-, IL-1[3-5] and IL-10[6], iNOS and COX-2[7], and anti-inflammatory mediator HO-1, which is macrophage or monocyte-related cytokine, essential for the inammatory response to pathogenic germs or toxicants[8]. Activation of pro-inammatory as well as anti-inflammatory cytokines and mediators is the key procedure of inammatory reaction which subsequently
lead to inflammatory impairment and restoration[9]. It
is well known that NO is synthesized by iNOS and involves in diverse physiological processes[10]. An
excess NO production is...