抄録
The antioxidant activities of plant extracts from Eysenhardtia platycarpa, E. punctata, and E. subcoriacea (Fabaceae) species, used in Mexican traditional medicine for the treatment of diabetes complications, were analyzed in a rat pancreas homogenate model. Methanolic extracts of E. platycarpa, E. punctata, and E. subcoriacea protected the pancreatic homogenate from 2,2-azo-bis(2-amidinopropane)dihydrochloride (AAPH)-induced damage. The inhibitory effect was dose-dependent at concentrations of 10—1000 ppm and correlated with 1,1 diphenyl-2-picrylhydrazyl (DDPH) radical scavenger capacity. 3-O-Acetyl-11α,12α-epoxy-oleanan-28,13β-olide (1, EC50=21.2±2.2 μM), (+)-catechin (2, EC50=7.4±1.1 μM), and (+)-catechin 3-O-β-D-galactopyranoside (3, EC50=11.5±1.5 μM), natural constituents isolated from the branches of E. platycarpa, displayed significant antioxidant activity. Compounds 1 and 2 significantly increased (p<0.001) the pancreatic glutathione (GSH) concentration alone and in combination with AAPH treatment. Compound 1 was obtained from oleanolic acid by relay synthesis via acetylation, bromo-lactonization, dehydrobromination, and oxidation, and its antioxidant effect was evaluated on streptozotocin (STZ)-induced diabetic rats. On its own, 1 at a dose of 100 mg/kg b. wt. (i.p.) for 5 d significantly increased the activities of glutathione peroxidase (GSHPx) and catalase (CAT). Simultaneous treatment of 1 (100 mg/kg b. wt.) and STZ significantly reduced the pancreatic thiobarbituric acid reactive substances (TBARS) concentration together with a significant increase in the activities of GSHPx and CAT, preventing hyperglycemia induced by STZ after 5 d of treatment. The present study demonstrates the antioxidant and antihyperglycemic activities of compound 1 isolated from Eysenhardtia species used in traditional medicine.
