Modulatory actions of garcinol and pterostilbene on cell proliferation, adipogenesis and inflammation in 3T3-L1 adipocytes

• Main Authors: Yu-Jyun Lin, 林俞君
• Other Authors: 顏國欽
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/857vbm

碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 98 === Obesity is a major obstacle to human health. It may predispose individuals to various diseases, such as type 2 diabetes, cardiovascular disease and cancer. Normally adipocytes can secrete inflammatory mediators, which in turn contribute to the low-level, chronic inflammation via stimulating infiltration of macrophages in adipose tissues. Besides, there are also increased inflammatory mediators such as tumor necrosis factor (TNF)-α、interleukin-6 (IL-6) and monocyte chemoatrractant protein-1 (MCP-1) in obese patients. Polyphenolic compounds have been well-studied for their biological activities. Garcinol isolated from the fruit rind of Garcinia spp. has been shown to have antioxidant, anti-inflammatory and anticancer properties. Pterostilbene isolated from Vaccinium berries can lower plasma cholesterol level and prevent atherosclerosis. However, the anti-obesity ability of these two compounds has not yet been studied. Thus the modulatory actions of garcinol and pterostilbene on cell proliferation, adipogenesis and inflammation in 3T3-L1 adipocytes were investigated. First, the effects of garcinol and pterostilbene on cell proliferation and adipogenesis in 3T3-L1 preadipocytes were investigated. The flow cytometry assay indicated that the treatment of 3T3-L1 preadipocytes with garcinol and pterostilbene caused cell cycle arrested at G2/M phase. During adipocytes differentiation, both garcinol and pterostilbene had inhibitory effect on fat droplet formation and triglyceride accumulation. For glycerol-3-phosphate dehydrogenase (GPDH) activity, the data indicated that garcinol and pterostilbene could inhibit the GPDH activity by 97.8 and 61.5%, respectively, as compared to the control. Both garcinol and pterostilbene significantly (p＜0.05) attenuated the protein expressions of adipogenic transcriptional factors peroxisome proliferator-activated receptor (PPAR)γ and CCAAT/ enhancer-binding proteins (C/EBP)α in maturing 3T3-L1 preadipocytes. Moreover, the lipid accumulation in the mature adipocytes was reduced by garcinol. Garcinol also modulated the obesity markers in vitro, such as PPARγ, C/EBPα, FAS, ATGL and adiponectin at protein level (p＜0.05). In addition, garcinol and pterostilbene had anti-adipogenesis effects on gene expression of leptin, resistin, adiponectin and FAS. These results suggest that garcinol and pterostilbene have anti-adipogenic effect on preadipocytes and adipocytes. We further examined whether these two compounds could decrease the production of inflammatory mediators by the interaction between 3T3-L1 adipocytes and RAW264.7 macrophages. The results showed that garcinol and pterostilbene could inhibit the TNF-α-induced NF-κB activation by suppressing phosphorylation of IκB and p65. The inflammatory genes such as COX-2, iNOS, IL-6 and IL-1β were also down-regulated by these two compounds (p＜0.05). The protein expression of COX-2 and secretion of IL-6 were also inhibited by treatment with garcinol or pterostilbene in adipocytes. Furthermore, the results indicated that garcinol and pterostilbene could reduce migration of macrophages to adipocytes in transwell coculture system. However, only pterostilbene suppressed (p＜0.05) the release of cytokines (IL-6 and TNF-α) and mRNA expression of several inflammatory genes (COX-2, iNOS, IL-6, TNF-α, CRP, MCP-1 and PAI-1) in contact coculture system. In addition, the effect of pterostilbene on inflammatory responses toward adipocytes and macrophages was also evaluated by in vitro model of conditioned medium experiment. The results indicated that both adipocytes and macrophages were targets for the suppressive effect of pterostilbene. In conclusion, garcinol and pterostilbene could reduce the lipid accumulation in 3T3-L1 adipocytes and inhibit TNF-α-induced inflammation via blocking NF-κB activation and reduce macrophage infiltration. Pterostilbene also could regulate the interaction between adipocytes and macrophages to suppress the level of inflammatory mediators. Our findings suggest that garcinol and pterostilbene may provide novel and useful application to reduce adipogenesis and inhibit the chronic inflammatory properties in adipocytes. These results may be potential for the treatment of obesity-related pathologies.