Anti-diabetic and renoprotective effects of Cassiae Semen extract in the streptozotocin-induced diabetic rats

Cassiae Semen, the dried seed of Cassia obtusifolia L. (Leguminosae), is a traditional Chinese medicine. It has long been used as the treatment of diabetic hyperlipidemia and diabetic constipation in Traditional Chinese Medicine formulae. The present study was designed to investigate the anti-diabetic and renoprotective effects of Cassiae Semen extract (CSE) in streptozotocin (STZ)-induced diabetic rats. Quality control of CSE was performed using HPLC. CSE were orally administered at 27, 54 and 81 mg/kg dose to high-sucrose-high-fat (HSHF) diet and STZ-induced diabetic rats for 60 days. Body weight, glucose metabolism and lipid metabolism profiles were measured to assess the anti-diabetic effect of CSE. Oxidative stress markers and inflammatory factors were determined using commercial kits. Renal function related parameters were also measured. Histopathological examination of kidney was conducted for the validation of pathological changes in the diabetic rats. Immunohistochemical examination of kidney was measured to investigate the expression of RAGE in renal tissues. Five compounds, including two anthraquinones and three naphtopyrones were simultaneously determined in CSE. Compared with diabetic control, groups treated with CSE exhibited an anti-diabetic effect, including a significant amelioration in body weight, glycemic control, oral glucose tolerance and lipid metabolism (P < 0.01). Moreover, oxidative stress and inflammatory responses decreased after oral administration of CSE (P < 0.01). CSE also showed protective effects on renal functions, decreasing the ratio of kidney/body weight, 24 h urine volume, 24 h urine protein, serum creatinine (Scr) and blood urea nitrogen (BUN) (P < 0.01). Additionally, renal protective effect was also observed in histopathological examination. Immunohistochemical analysis showed that CSE downregulated the expression of RAGE. It turned out that CSE had both anti-diabetic and renoprotective effects in diabetic rats. CSE can be a potential agent in the treatment of type 2 diabetes mellitus (T2DM) and its complications.