Rapid increase in the prevalence of obesity-related metabolic inflammatory diseases has led to research focused on nutraceuticals for their treatment. This study investigated the effects of the ethanol extracts of mung bean testa (MBT) on the metabolic inflammation-induced lipogenesis in gastrocnemius muscle of KK-Ay diabese mice. Ethanol extracts of MBT were orally administered to diabese KK-Ay mice for 4 weeks after diet-induced obesity model was generated by feeding a 60% high-fat diet for 3 weeks. Although there were no changes in body weight gain, MBT treatments decreased total weight of white adipose tissue. MBT also decreased triacylglycerol and total cholesterol levels in the muscle by 30%, which was correlated with suppression of lipogenic genes such as ACC, C/EBP alpha, PGC-1 alpha, and PPAR gamma. In particular, decreased levels of p-ERK1/2, PPAR gamma, and C/EBP alpha in the MBT-treated groups suggest that MBT might inhibit adipogenesis and decrease differentiation via the MEK/ERK pathway. Furthermore, significantly lower amounts of plasma interleukin (IL)-6 and intramuscular tumor necrosis factor (TNF)-alpha and monocyte chemoattractant protein-1 (MCP-1) were detected in MBT groups, confirming the anti-inflammatory effect of mung bean. In addition, our in vitro pilot study with 3T3-L1 cells showed that vitexin, the functional chemical in MBT, inhibited inflammation-induced lipogenesis with significantly lower amounts of IL-6 and MCP-1 after 14 days of vitexin treatment. Thus, the functional compounds in the mung bean ethanol extracts such as vitexin and isovitexin may regulate intracellular lipogenesis and adipogenesis via anti-inflammatory mechanisms and MEK/ERK pathway in the KK-Ay mouse model.
Keywords: C/EBPα; ERK1/2; PGC-1α; PPARγ; Vigna radiata L.; adipogenesis; adipokines; diabese; metabolic inflammation; mung bean.