Orostachys japonicus A. Berger (Crassulaceae) Exerts Antidiabetic Activity by Improving Glucose and Lipid Levels in Type 2 Diabetic Mice

Orostachys japonicus A. Berger and Momordica charantia Linn have been widely used as an alternative medicine. Recently, patients with type 2 diabetes (T2D) have paid increasing attention to medical nutrition therapy due to its safety and cost-effectiveness. Therefore, we have developed a new health functional food that consists of a mixed extract of O. japonicus and M. charantia. The aim of this study is designed to assess the antidiabetic efficacy of O. japonicus and M. charantia extracts (OME, in an 8:2 ratio), especially focusing on the effects of O. japonicus via in vivo and in vitro experiments. Seven-week-old C57BL/Ksj-db/db (db/db; a genetic animal model of T2D) mice were used for inducing diabetes. Mice were administered with various concentrations of OME (OME 0, 100, 200, or 400 mg/kg/day) for 6 weeks. Metabolic parameters, fasting blood glucose and glycosylated hemoglobin levels were measured. Histopathologic analysis and the levels of serum or hepatic biochemicals were assessed to evaluate diabetic liver injury and steatosis. The expression levels of lipogenic and gluconeogenic genes were determined by quantitative real-time polymerase chain reaction. Activation of Akt was assessed by western blot analysis. Administration of OME significantly improved metabolic parameters in db/db mice, and also reduced diabetic liver injury and steatosis were observed by OME administration in db/db mice as confirmed by histopathologic and serum or hepatic biochemical analysis. Consistently, treatment of OME significantly increased Akt activation resulting in decreased expression levels of lipid-accumulation or gluconeogenesis-related genes. Similar results were observed in in vitro experiments using single extract of O. japonicus and using OME. OME has antidiabetic effects with increased insulin sensitivity, and may be a safe alternative therapy for the management of T2D.