In Vitro and in Vivo Evaluation of Isolated Compounds From Polyherbal Extracts for Enzyme Inhibition in Diabetes Mellitus

The clinical value of most of the traditional polyherbal preparations in diabetes mellitus is in a disadvantaged position since they have not been characterized in terms of their active principles and their exact mechanism of action. The objective of the present exploration was the isolation, characterization, and assessment of the antidiabetic activity of selected compounds in a polyherbal mixture (Phaseolus vulgaris, Trigonella foenum-graecum, Panax ginseng, Spinacia oleracea) by means of bio-guided fractionation process aimed at carbohydrate-digesting enzymes. A-glucosidase and a-amylase in vitro inhibition by the methanol extract of the polyherbal combination was significant. Through bioassay-directed purification, CPH-01, a flavonoid glycoside, and CPH-02, a derivative of phenolic acid, were purified. Enzymatic tests in vitro showed that CPH-01 was an extremely active and selective a-glucosidase inhibitor (IC50 = 12.3 uM) with an activity about 5-fold higher than that of the standard medication acarbose. CPH-01 (100 mg/kg/day 4 weeks) as an oral solution was found to induce remarkable antihyperglycemic effects in high fat diet/streptozotocin rat model of type 2 diabetic rats, with a significant reduction in fasting blood glucose (by 58.4%), glucose tolerance and HgA1c. This treatment also alleviated diabetic dyslipidemia and served as an improvement of hepatic and renal functional markers and enhanced antioxidant defenses in pancreatic tissue by increasing SOD, CAT and GSH levels and decreasing lipid peroxidation. A toxicity study in acute oral case had defined a good safety profile of CPH-01 at a limit dose of 2000 mg/kg. Molecular docking experiments showed that CPH-01 is a potent inhibitor due to the presence of strong hydrogen-bonds with active site residues (Asp215, Glu277, Arg442) in the a-glucosidase active site. Finally, this study has been able to designate CPH-01 as the novel, potent, and selective a-glucosidase inhibitor, having high in vivo efficacy and antioxidant capacity, making it a successful polyherbal formulation, and a characterized lead drug in developing a multi-target phytotherapeutic agent to manage diabetes.