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Black soybeans (Glycine max (L.) Merr.) are known to be rich in polyphenols, including anthocyanins, and they have been consumed since ancient times for their beneficial effects on health. In addition, it has been reported that black soybean (BS) seed coat may ameliorate obesity and insulin resistance. In the present study, we administered BS extract to type 2 diabetics for 2 months to investigate the effects of BS on glycemic control and lipid metabolism parameters. In addition, we administered BS and antihyperlipidemic agent, fenofibrate, to patients with type 2 diabetes complicated by postprandial hyperlipidemia for 2 months and assessed the combined effects of fenofibrate and BS on serum lipid profile. The results showed that administration of the BS alone had no effect on the blood glucose or lipid levels, but that administration of fenofibrate alone and fenofibrate in combination with the BS significantly lowered their serum triglyceride (TG) level at fasting state, and the percent decrease in the serum TG level after combined administration was significantly higher than in the subjects who received fenofibrate alone. Furthermore, the serum LDL cholesterol concentration, which did not decrease when fenofibrate was administered alone, decreased significantly when the BS and fenofibrate were administered in combination. These results suggest that combined administration of the BS with fenofibrate enhanced the antihyperlipidemic action of fenofibrate, and the results of this study demonstrated the usefulness of the BS in clinical practice.

The increased number of patients with type 2 diabetes (T2D) has become a worldwide problem, and insulin sensitizers such as thiazolidinediones (TZDs) are used as therapeutic agents. We found that extracts of Vitex trifolia L. (V. trifolia), a medicinal plant from Myanmar, induced adipogenesis similar to rosiglitazone (ROS), which is a TZD, in 3T3-L1 preadipocytes. In the present study, we attempted to isolate from V. trifolia those compounds that showed ROS-like effects. Among the extracts of hexane, ethyl acetate, and methanol obtained from V. trifolia, the ethyl acetate extract with the strongest ROS-like effects was purified by various chromatographic methods to obtain three known compounds: vitexilactone (1), vitexicarpin (2) and oleanolic acid (3). Among the isolated compounds, the ROS-like action of 1 was the strongest. The effects of 1 on 3T3-L1 cells during adipogenesis were compared with those of ROS. Both 1 and ROS increased lipid accumulation, the expression of adiponectin and GLUT4 in the cell membrane and decreased both the size of adipocytes and the phosphorylation of IRS-1, ERK1/2 and JNK in 3T3-L1 cells. In contrast, unlike ROS, the induction of proteins involved in lipogenesis was partial. ROS-like effects of 1 in 3T3-L1 cells were suppressed by the addition of bisphenol A diglycidyl ether (BADGE), one of a peroxisome proliferator-activated receptor γ (PPARγ) antagonists, suggesting that the action of 1 on adipocytes is mediated by PPARγ. From the results of the present study, it can be concluded that 1 is a novel insulin sensitizer candidate.

Eleutherococcus sieboldianus (Makino) Koidz. is a local product from the area in and around Yonezawa City in Yamagata Prefecture, Japan. It has been used as a medicinal plant for a long time. We isolated and identified four types of flavonoid glycosides [astragalin (1), isoquercetin (2), rhamnocitrin 3-O-glucoside (3), and nicotiflorin (4)], a triterpene [methyl hederagenin (5)], and three types of triterpene glycosides [δ-hederin (6), echinocystic acid 3-O-arabinoside (7), and cauloside B (8)] from the methanol extract of E. sieboldianus, which regulates lipid accumulation in 3T3-L1 preadipocytes. Among the compounds isolated, 2 and 8 up- and down-regulated lipid accumulation and insulin induced adipocyte differentiation in 3T3-L1 preadipocytes. Compound 2 induced up-regulation of lipid accumulation and decreased adipocyte size, while 8 down-regulated lipid accumulations without decreasing cell size. Additionally, 2 increased adipogenic proteins [peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and fatty-acid-binding protein 4 (FABP4)]. In contrast, 8 decreased the levels of all adipogenic proteins and glucose transporter type 4 (GLUT4), but increased adiponectin.

Background: SGLT2 inhibitor enhances not only glucose excretion but also fatty acid utilization. Those facts suggest that SGLT2 inhibitor affects fat accumulation and lipid storage. Objective: In the present study, we evaluated the effects of dapagliflozin on fatty acid composition and gene expression involved in fatty acid metabolism in rat adipose and liver tissues. Methods: We administered 1 mg/kg/day dapagliflozin for 7 weeks to male high-fat-fed rats (DAPA group), and then weights and 22 fatty acid contents in the epididymal (EPI), mesenteric (MES), retroperitoneal (RET), and subcutaneous (SUB) adipose tissues, and the liver were compared with the vehicle-administered control group. Results: In the EPI, RET, and SUB in the DAPA group, contents of several fatty acids were lower (P<0.05) than those in the control group, while no significant difference was detected in tissue weight. In the MES, tissue weight and a wide variety of fatty acid contents, including saturated, monounsaturated, and polyunsaturated fatty acids, were lower (P<0.05). As for the liver tissue, no significant difference was observed in fatty acid contents between the groups. mRNA expression of Srebp1c in EPI was significantly higher (P<0.05) in the DAPA group than in the control group, while Scd1 expression in the liver was lower (P<0.01). Conclusion: These results suggest that dapagliflozin might suppress lipid accumulation especially in the MES, and could reduce contents of fatty acids not in the liver but in adipose tissues in high-fat-fed rats. In addition, dapagliflozin could influence mRNA expression involved in lipogenesis in the EPI and liver.

It is known that black soybean (BS) extract, rich in polyphenols, has beneficial effects against obesity, inflammation and insulin resistance. However, detailed effects of BS on lipid metabolism have not been documented well. In the present study, we compared fatty acid composition in visceral and subcutaneous adipose tissues of high-fat fed (HFF) rats and BS administered HFF rats. Black soybean administration for 6 weeks influenced neither body nor adipose tissue weights, blood glucose, plasma insulin levels, or insulin sensitivity. However, BS reduced several saturated (C14:0 and C16:0), monounsaturated (C14:1n-5 and C18:1n-9) and n-6 polyunsaturated (C18:2n-6, C20:3n-6, C20:4n-6 and C22:4n-6) fatty acid contents in subcutaneous fat without any change in n-3 polyunsaturated fatty acid contents. No such effect was observed in fatty acid composition in visceral fat. Long-chain fatty acids are involved in regulation of inflammation. Therefore, those reduced fatty acids may be linked to the effects on suppressing inflammation.