Antidiabetic Efficacy of Ethanolic Extracts of Cyperus Rotundus Rhizome, Rhodiola Rosea Root and Zostera Marina Leaf and Their 1:1:1 Polyherbal Mixture in Streptozotocin-Induced Diabetic Wistar Rats Polyherbal Antidiabetic Evaluation in Streptozotocin-Diabetic Rats

Abstract

Purpose: The main objective of the current research work was to evaluate the antidiabetic efficacy of 70% ethanolic extracts of Cyperus rotundus rhizome (CR), Rhodiola rosea root (RR) and Zostera marina leaf (ZM), and of a 1:1:1 polyherbal mixture of the three extracts (MIX), in streptozotocin (STZ)-induced diabetic Wistar rats. The single extracts and the mixture were compared at the same total oral dose (250 mg/kg/day) against metformin (50 mg/kg/day). To our knowledge, this combination of a terrestrial sedge, an alpine adaptogen and a marine angiosperm has not been tested in an STZ model earlier.
Methods: Thirty-five male Wistar rats were allocated by computer-generated randomisation to seven groups of five (normal control, diabetic control, metformin, CR, RR, ZM and MIX). Diabetes was induced in 30 rats by a single intraperitoneal dose of STZ (55 mg/kg in citrate buffer, pH 4.5), and rats with fasting glucose of 300 mg/dL or more at 72 h were included. Treatments were given by oral gavage once daily for 28 days. Fasting blood glucose and body weight were recorded weekly, and HbA1c, serum lipid profile, ALT, AST and creatinine were measured at termination. Treated groups were compared with diabetic control by Dunnett's test and with each other by Tukey's test.
Results: All 30 STZ rats were included (72 h glucose 339 to 535 mg/dL) and no animal died. At week 4, fasting glucose was 94 ± 9 mg/dL in normal control and 439 ± 48 mg/dL in diabetic control, and it was lowered to 264 ± 57 mg/dL by metformin (40%), 243 ± 70 mg/dL by CR (45%), 272 ± 48 mg/dL by RR (38%), 300 ± 67 mg/dL by ZM (32%) and 235 ± 50 mg/dL by MIX (46%) (Dunnett, all p < 0.01). HbA1c fell from 8.8 ± 0.5% in diabetic control to 6.9 to 7.7% in the treated groups (p < 0.05), and total cholesterol, triglycerides, LDL-C, HDL-C, ALT, AST and creatinine moved towards normal in all five treated groups. MIX carried one-third of the single-extract dose of each plant and gave the lowest mean glucose, total cholesterol, triglycerides, LDL-C and creatinine, but no two treated groups differed significantly (Tukey, smallest p = 0.18).
Conclusion: It can be concluded that the three ethanolic extracts and their 1:1:1 mixture lowered fasting glucose, HbA1c and the atherogenic lipids in STZ-diabetic rats to about the same extent as metformin, and that the mixture did so at one-third of the dose of each constituent. Dose-response arms for each extract and a factorial design are the next steps for the mixture.