Anti-diabetic and anti-obesitic effects of aqueous extracts of Yangkyuksanhwa-tang and its two major compositions on db/db mice

Type 2 diabetes mellitus (T2DM) is a metabolic syndrome that results from target-tissue resistance to insulin. Obesity is the condition of excess body fat accumulation. T2DM and obesity are both associated with hypertension, hyperlipidemia, and abdominal obesity. In Korean medicine, Yangkyuksanhwa-tang (YKSHT) has been prescribed for patients with T2DM. Oral glucose tolerance tests (OGTT), multiplex assays and hemoglobin A1C (HbA1C) assessments were performed to determine the anti-diabetic effects of YKSHT and two major compositions of YKSHT, Lonicera japonica Thunb. (LJT) and Rehmannia glutinosa (RG) on db/db mice, a rodent model for T2DM. To study the anti-obesitic effects of LJT, RG or YKSHT, blood profiling including the triglycerides (TGs) and the total, LDL and HDL cholesterol levels were measured. In addition, body index measures such as the liver, retroperitoneal and epididymal fat tissues were collected and weighed. Mice treated with RG or YKSHT showed reduced blood glucose levels after stimulating the plasma GLP-1 levels. The multiplex assay results support the weight-controlling effects of the LJT, RG and YKSHT treatments, showing reducing levels of ghrelin and the induction of peptide YY (PYY) secretion. The YKSHT treatment reduced plasma TG levels and increased HDL cholesterol levels. The weights of the liver, retroperitoneal and epididymal fat tissues were reduced after the YKSHT treatment. Hence, we suggest that YKSHT can be utilized for the prevention and treatment of T2DM and obesity simultaneously.