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Inula japonica Thunb. (Asteraceae) is a flowering plant that grows mainly in Korea, Japan, and China and its flower extract has diverse biological effects such as anti-inflammatory and antioxidative activities. However, the effects on obesity and enhancement of endurance capacity have not been explored yet. This study aims to reveal the effects of I. japonica flower ethanol extract (IJE) on obesity and endurance capacity in high-fat diet (HFD) fed C57BL/6J mice and the mechanism. IJE inhibited lipid accumulation in 3T3-L1 adipocytes in vitro. Also, IJE-fed mice showed reduced body weight gain, hepatic lipid, and body fat mass, and increased muscle weight. IJE reduced lipid accumulation in the liver and adipose tissue by decreasing lipogenic and adipogenic gene expression. Additionally, consumption of low-dose IJE significantly enhanced endurance capacity via increasing AMP-activated protein kinase activity and mRNA levels of Myh7 and Myh2. Luteolin and 1β-hydroxyalantolactone (1β-HA), compounds of IJE, are involved in anti-adipogenesis in the 3T3-L cells and only luteolin increased the protein levels of MHC during C2C12 myoblast differentiation. Collectively, our results suggest that consumption of IJE not only helps to prevent obesity but also enhances endurance capacity reduced by HFD. [ABSTRACT FROM AUTHOR]

Recent studies show that brown rice improves glucose intolerance and potentially the risk of diabetes, although the underlying molecular mechanisms remain unclear. One of the phytochemicals found in high concentration in brown rice is γ-oryzanol (Orz), a group of ferulic acid esters of phytosterols and triterpene alcohols. Here, we found that Orz stimulated differentiation of 3T3-L1 preadipocytes and increased the protein expression of adipogenic marker genes such as peroxisome proliferator-activated receptor gamma (PPAR-γ) and CCAAT/enhanced binding protein alpha (C/EBPα). Moreover, Orz significantly increased the glucose uptake in insulin-resistant cells and translocation of glucose transporter type 4 (GLUT4) from the cytosol to the cell surface. To investigate the mechanism by which Orz stimulated cell differentiation, we examined its effects on cellular signaling of the mammalian target of rapamycin complex 1 (mTORC1), a central mediator of cellular growth and proliferation. The Orz treatment increased mTORC1 kinase activity based on phosphorylation of 70-kDa ribosomal S6 kinase 1 (S6K1). The effect of Orz on adipocyte differentiation was dependent on mTORC1 activity because rapamycin blocks cell differentiation in Orz-treated cells. Collectively, our results indicate that Orz stimulates adipocyte differentiation, enhances glucose uptake, and may be associated with cellular signaling mediated by PPAR-γ and mTORC1.