Evaluation of α-Glucosidase Inhibition and Antihyperglycemic Activity of Extracts Obtained from Leaves and Flowers of Rumex crispus L.

Among antihyperglycemic drugs used for treating diabetes, α-glucosidase inhibitors generate the least adverse effects. This contribution aimed to evaluate the potential antidiabetic activity of Rumex crispus L. by testing its in vitro α-glucosidase inhibition and in vivo antihyperglycemic effects on rats with streptozotocin (STZ)-induced diabetes. Better inhibition of α-glucosidase was found with the methanol extract versus the n-hexane and dichloromethane extracts. The methanol extract of the flowers (RCFM) was more effective than that of the leaves (RCHM), with an IC50 of 7.3 ± 0.17 µg/mL for RCFM and 112.0 ± 1.23 µg/mL for RCHM. A bioactive fraction (F89s) also showed good α-glucosidase inhibition (IC50 = 3.8 ± 0.11 µg/mL). In a preliminary study, RCHM and RCFM at 150 mg/kg and F89s at 75 mg/kg after 30 days showed a significant effect on hyperglycemia, reducing glucose levels (82.2, 80.1, and 84.1%, respectively), and improved the lipid, renal, and hepatic profiles of the rats, comparable with the effects of metformin and acarbose. According to the results, the activity of R. crispus L. may be mediated by a diminished rate of disaccharide hydrolysis, associated with the inhibition of α-glucosidase. Thus, R. crispus L. holds promise for the development of auxiliary drugs to treat diabetes mellitus.

Synthesis and Molecular Docking Studies of Alkoxy- and Imidazole-Substituted Xanthones as α-Amylase and α-Glucosidase Inhibitors.

Current antidiabetic drugs have severe side effects, which may be minimized by new selective molecules that strongly inhibit α-glucosidase and weakly inhibit α-amylase. We have synthesized novel alkoxy-substituted xanthones and imidazole-substituted xanthones and have evaluated them for their in silico and in vitro α-glucosidase and α-amylase inhibition activity. Compounds 6c, 6e, and 9b promoted higher α-glucosidase inhibition (IC50 = 16.0, 12.8, and 4.0 µM, respectively) and lower α-amylase inhibition (IC50 = 76.7, 68.1, and >200 µM, respectively) compared to acarbose (IC50 = 306.7 µM for α-glucosidase and 20.0 µM for α-amylase). Contrarily, derivatives 10c and 10f showed higher α-amylase inhibition (IC50 = 5.4 and 8.7 µM, respectively) and lower α-glucosidase inhibition (IC50 = 232.7 and 145.2 µM, respectively). According to the structure-activity relationship, attaching 4-bromobutoxy or 4'-chlorophenylacetophenone moieties to the 2-hydroxy group of xanthone provides higher α-glucosidase inhibition and lower α-amylase inhibition. In silico studies suggest that these scaffolds are key in the activity and interaction of xanthone derivatives. Enzymatic kinetics studies showed that 6c, 9b, and 10c are mainly mixed inhibitors on α-glucosidase and α-amylase. In addition, drug prediction and ADMET studies support that compounds 6c, 9b, and 10c are candidates with antidiabetic potential.