Antidiabetic activity, toxicity, and phytochemical evaluation of solanum terminale forsk (solanaceae)

Abstract

ABSTRACT Background: Based on WHO and IDF data, prevalence of diabetes disease is on the rise. Majority of the population especially in the developing world depend on herbal medicine being their primary source for medicines or the preferred treatment. This is due to the limited access of modern conventional medicines as well as to avoid side effects associated with various oral hypoglycemic agents and insulin analogues. Aim of the study: This study aimed at exploring the antidiabetic, toxicity profile, phytochemical classes of compounds of Solanum terminale (fruits), a Tanzanian medicinal plant claimed to have hypoglycemic effects. Methodology: The study was experimental design. Fruits of S. terminale were collected from Lushoto. Identification was done using herbaria specimen and the voucher specimen was deposited at the ITM herbarium – MUHAS. Extracts were prepared by exhaustive maceration using 95% ethanol, dried in rotary evaporator and then fractionated with dichloromethane, ethyl acetate, methanol and water. Antidiabetic testing employed healthy albino mice involved in Oral Glucose Tolerance Test (OGTT) and Alloxan models. In both models, mice were treated with single doses of 100 mg/kg of extract and fractions. In alloxan model, mice were induced with diabetes by intraperitoneal injection of freshly prepared alloxan monohydrate 170 mg/kg BW, and the diabetic mice were treated daily for the period of 20 days, and FBG were recorded on day 1, 5, 10, 15 and 20. Both experiments included 5% ethanol treated mice as negative control group and chlorpropamide 100 mg/kg BW treated mice as positive control group. Acute oral toxicity followed OECD guideline using a single dose of 2000 mg/kg BW, and the treated mice were observed for 14 days for their mortality, behavioral and other changes. Before sacrifice, the weight of animals and the visceral organs were recorded, and then sent for histological evaluations. The phytochemical screening was performed by using standard qualitative procedures of colour reactions. Results were expressed as mean ± SD, analysed by independent student’s t-test, p <0.05 was considered as significant level. Ethical clearance was sought from MUHAS, IRB and animal care followed the EEC Directive of 1986; 86/609/EEC. Results: The extraction yield was 4.4%, while the fraction yields were 57.20, 9.35, 8.95 and 6.80% for MeOH, H2O, EtOAc and DCM, respectively. Crude ethanolic fruit extract of S. terminale and fractions demonstrated clinical and statistical significant blood glucose lowering efficacy in OGTT and Alloxan models (p<0.05). Neither death nor abnor¬mal changes in behavioral features in tested mice observed at 2000 mg/kg BW of S. terminale crude ethanolic fruit extract. Although the histological analysis demonstrated some organ derangements at higher dose, the fruits are probably safe for use in low doses. Tannins, cardiac glycosides, steroids, terpenoids, alkaloids, flavonoids and saponins were found to be the phytochemicals present in S. terminale crude ethanolic fruit extract. Conclusion: This study supports the claim of the traditional use of S. terminale fruits in diabetes management in Lushoto, especially from the crude ethanolic extract which showed activity in both OGTT and Alloxan models. Since the best activity was obtained from the crude extract, it is possible that, polar and less polar compounds are working in a synergistic manner for the reduction of blood glucose levels. As observed, the antidiabetic dose of the crude ethanolic extract i.e. 100 mg/kg BW is far much low when compared to the toxic dose tested of 2000 mg/kg BW, this plant qualifies for further work in search of antidiabetic compounds/standardization of herbal medicine. Further work is needed including more antidiabetic screening exhausting other techniques, toxicological studies, identification of the active compounds, and standardization/formulation of S. terminale fruits products. Keywords: S. terminale, phytoconstituents, acute oral toxicity, diabetes mellitus. IKISIRI