Antiadipogenesis of Oroxylum indicum (L.) Kurz Extract via PPARγ2 in 3T3-L1 Adipocytes

Oroxylum indicum is regarded as a traditional food with medicinal properties and is used widely throughout Asia. It has previously been demonstrated that O. indicum extract (OIE) was able to suppress the differentiation of 3T3-L1 preadipocytes to adipocytes. However, the mechanism underlying the antiadipogenesis of this plant has not been fully investigated. The present study aimed to explore the impact of OIE at 50 to 200 μg mL(−1) on the molecular mechanism involved in the antiadipogenic activity in 3T3-L1 cells at day 0 of their differentiation to adipocytes. The morphology and biochemistry of the cells on day 12 were investigated and compared to the relevant controls. Adiponectin was measured using enzyme-linked immunosorbent assay (ELISA). The mRNA expression of peroxisome proliferator-activated receptor-gamma 2 (PPARγ2), sterol regulatory element-binding proteins 1c (SREBP-1c), fatty acid synthetase (FAS), glucose transporter (GLUT4), and leptin in adipocytes was determined by real-time PCR. The results demonstrated that the OIE at 200 μg mL(−1) exhibited strongest suppression on intracellular lipid accumulation. The levels of adiponectin were dramatically increased in the untreated adipocytes, whereas significantly decreased in the 200 μg mL(−1) OIE-treated adipocytes (P < 0.05). Expression of the mRNAs revealed that OIE-treated adipocytes at 200 μg mL(−1) significantly inhibited the expression of PPARγ2 and SREBP-1c and lowered the level of expression of GLUT4, FAS, and leptin compared to the control (P < 0.05). These findings suggest that OIE inhibits adipocyte differentiation along with the downregulation of PPARγ2, SREBP-1c, and GLUT4, leading to the decrease in the expression of FAS and adipokine (leptin and adiponectin). Thus, OIE might be developed for hyperlipidemia and obesity prevention.