BIOCHEMICAL AND MOLECULAR STUDIES of Tapinanthus cordifolius AND Irvingia wombolu LEAVES IN HIGH-FAT DIET AND STREPTOZOTOCIN-INDUCED DIABETIC RATS

Over 80% of the population from developing countries depend on medicinal plants as the primary health care source for managing diabetes. Globally, the prevalence of diabetes is rapidly on the increase and the high cost of treatment is a significant cause for concern. This study investigated the in vitro, in silico and in vivo phytochemical, antioxidant, toxicological and antidiabetic activities of Irvingia wombolu (IW) and Tapinanthus cordifolius (TC) leaf extracts. The leaves of TC and IW were extracted singly using 85% ethanol and fractionated sequentially using n-hexane, ethyl-acetate, butanol, and water. Phytochemical screening, in vitro antioxidant and antidiabetic studies of the extract and solvent fractions, were carried out using standard methods. The extract with the highest in vitro antioxidant and antidiabetic activities was further used for the in silico and in vivo studies. Bioactive compounds were identified using gas chromatography/mass spectrometry (GC/MS). In silico assessment of the identified compounds was carried out by molecular docking. Furthermore, acute and sub-chronic toxicity studies were assessed in male and female mice and rats respectively. The animal diabetes model was induced using a high-fat diet and a single low dose of streptozotocin (40 mg/kg). Blood glucose levels of diabetic rats were monitored at various time intervals for 6 h after TC extract administration (200, 400 and 800 mg/kg/day) and then every 7 days till the 21st day. The oral glucose tolerance test (OGTT) was carried out on normal rats by administering 2000 mg/kg glucose solution and measuring the blood glucose value every hour for 2 h. At the end of the toxicological and diabetes studies, the animals were euthanized and sacrificed. Organs were harvested for histological and molecular studies, while serum was collected for haematological and biochemical analyses. The preliminary phytochemical screening revealed the presence of phenols, tannins, flavonoids, steroids, and anthraquinones in both plants; saponin, terpenes in IW with cardiac glycosides and alkaloids in TC. Quantitative analysis of the plant showed that the crude extract of TC is richer in phenols, flavonoids and tannins than IW. The TC showed the highest antioxidant activity and exhibited significant inhibition on α-amylase, α-glucosidase and lipase with IC50 values of 22.72, 542 and 494 μg /mL, respectively, when compared to IW with values of 37.89, 966.75 and 910.49 μg /mL respectively. From the insilico studies, the alpha-tocopherol-beta-D-mannoside, 5-ergosterol, acetosyringone, benzaldehyde, 4-(ethylthio)-2,5-dimethoxy, 5-trimethoxybenzoic acid, and campesterol of the 44 identified GC-MS phytoconstituents from TC extract were established as potent inhibitors of α-amylase, α-glucosidase and lipase. The acute and sub-chronic toxicity studies showed no deaths at the highest extract dose. No significant (p