(+)-Terrein exerts anti-obesity and anti-diabcetic effects by regulating the differentiation and thermogenesis of brown adipocytes in mice fed a high-fat diet

Objective: (+)-Terrein, a low-molecular-weight secondary metabolite from Aspergillus terreus, inhibits adipocyte differentiation in vitro. However, the precise mechanisms underlying the effects of (+)-terrein on adipocytes remain unclear. We hypothesized that (+)-terrein modulates adipogenesis and glucose homeostasis in obesity and diabetes via anti-inflammatory action and regulation of adipocyte differentiation. Hence, in this study, we aimed to investigate the in vivo anti-diabetic and anti-obesity effects of (+)-terrein. Methods: Male C57BL/6 J mice were fed normal chow or high-fat (HF) diet and administered (+)-terrein (180 mg/kg) via intraperitoneal injection. Glucose and insulin tolerance tests, serum biochemical assays, and histological analyses were also performed. Rat brown preadipocytes, mouse brown preadipocytes (T37i cells), and inguinal white adipose tissue (ingWAT) preadipocytes were exposed to (+)-terrein during in vitro adipocyte differentiation. Molecular markers associated with thermogenesis and differentiation were quantified using real-time polymerase chain reaction and western blotting. Results: (+)-Terrein-treated mice exhibited improved insulin sensitivity and reduced serum lipid and glucose levels, irrespective of the diet. Furthermore, (+)-terrein suppressed body weight gain and mitigated fat accumulation by activating brown adipose tissue in HF-fed mice. (+)-Terrein facilitated the in vitro differentiation of rat brown preadipocytes, T37i cells, and ingWAT preadipocytes by upregulating peroxisome proliferator-activated receptor-γ (PPARγ). This effect was synergistic with that of a PPARγ agonist. Conclusion: This study demonstrated that (+)-terrein effectively induces PPARγ expression and brown adipocyte differentiation, leading to reduced weight gain and improved glucose and lipid profiles in HF-fed mice. Thus, (+)-terrein is a potent novel agent with potential anti-obesity and anti-diabetic properties.