Evaluation of the Hypoglycemic Activity of Methanol Extract of Icacina Trichantha Tuber in Alloxan‐Induced Diabetic Rats and Isolation of the Active Principle
Authors: Onakpa Monday Michael , Ode Julius Okwoche , Kolawole Victor Olumayowa , Ajagbonna Peter Olatunde , Asuzu Isaac Uzoma 
Published: June 2021

Icacina trichantha tuber, traditionally acclaimed for its efficacy in the treatment of food poisoning, constipation, diabetes mellitus, malaria, and impotence was in this study evaluated for hypoglycaemic activity in alloxan‐induced diabetic rats, and also the hypoglycaemic principle was isolated and characterized. In vitro toxicity studies was conducted on MDA‐MB‐435 human melanoma, HT‐29 human colon cancer and 3T3‐L1 mouse embryonic fibroblast cell lines while in vivo acute and chronic toxicity studies were performed with varying doses of the extract in rats. The effects of I. trichantha tuber extract on blood glucose levels were investigated in vivo using the oral glucose loading and pancreatic β‐cells destruction with alloxan monohydrate. Thirty (30) rats weighing between 150 and 200 g were randomly assigned to 5 groups (A–E) of 6 rats each. Group A (negative control) was given distilled water (10 ml/kg), group B (positive control) received glibenclamide (2 mg/kg) while groups C, D and E were administered 200, 400 and 600 mg/kg of the extract respectively. The active fractions were isolated following further bioassay‐guided chromatographic separation techniques. Data collected were analyzed using one‐way analysis of variance.. Mean differences were considered significant at p < 0.05. The extract was tolerated by the rats up to the dose of 5000 mg/kg per os. Icacina trichantha tuber extract caused a significant (p < 0.05) dose‐dependent reduction of blood glucose at 400 mg/kg and 600 mg/kg (per os) when compared to the control group at 6 hours, 12 hours and on days 7, 14 and 21of treatment. The tuber extract also improved the symptoms of Diabetes mellitus by significantly (p < 0.05) increasing the serum HDL and reducing serum LDL and triglycerides. The 400 mg/kg extract and 600 mg/kg extract resulted to a significant (p < 0.05) decrease in serum triglycerides levels on 21st day when compared to the diabetic control group. Chronic administration of I. trichantha tuber extract in feed did not show any significant (p < 0.05) difference in the haematological parameters nor was there any marked histopathological lesion. Five compounds were isolated from Icacina trichantha tuber extract viz 17‐Hydroxy‐icacinol, Icacinol, Humirianthol, Humirianthenolide C, and Icacenone. 17‐Hydroxy‐icacinol exerted about 48% reduction of hyperglycemia in diabetic rats and thus identified as the most active. All five compounds displayed significant cytotoxicity on the MDA‐MB‐435 cell line (IC50 0.66–6.44 μM), while Icacinol, Humirianthol, and Humirianthenolide C exhibited cytotoxic activity on the HT‐29 cells (IC50 3.00 – 4.94 μM). This study validates the folkloric use of the tuber and led to the isolation of three 9βH‐pimarane diterpenes (17‐Hydroxy‐icacinol, Icacinol, and Humirianthol), and two 17‐nor‐9βH‐pimarane diterpenes (Humirianthenolide C, and Icacenone) from the tuber of I. tricantha.Support or Funding InformationInstitute of International Education of the United States, Fulbright Junior Scholar Development Award (Grantee ID No. 15120356).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.