Screening for toxicological and anti-diabetic potential of n-hexane extract of Tapinanthus bangwensis leaves

Health forecasters predict that cases of diabetes will double in 2030; hence proactive action is required to salvage this problem. Thus, this study was undertaken to evaluate the toxicological and anti-diabetic potential of n-hexane extract of T. bangwensis leaves on α-amylase and α-glucosidase activity. The phytochemical screening, antioxidant activity as well as the inhibitory effect of the plant extract was determined by UV-spectrophotometry method while brine shrimp and Allium cepa methods were used for the toxicity study. Preliminary phytochemical screening detected the presence of flavonoid, phenol, tannin, alkaloid and cardiac glycoside whereas phlobatanin, steroid, terpenoid and saponin were absent. The result also showed that flavonoid concentration was the highest compared to others. The 2,2-diphenyl-1-picrylhydrazine (DPPH) and nitric oxide (NO) results showed that the plant extract exhibited significant antioxidant activity particularly at the highest concentration (100 µg/ml). Brine shrimp lethality result showed that the highest mortality rate of nauplii and median inhibition concentration (IC50) are 97% and 7.46 ± 0.33 µg/ml respectively. Furthermore, the results also revealed that mitotic index, root growth length and mitotic division (cytotoxicity indicators) decreased as concentration increases. Finally, the results showed that the plant extract exhibited significant inhibitory effect on α-amylase and α-glucosidase activities at 100 µg/ml; nevertheless, the effect was higher on α-amylase than α-glucosidase activity. In summary, the significant antioxidant and inhibitory effects may be attributed to the presence of the phytochemicals mentioned above. It can therefore be concluded that T. bangwensis leaves may demonstrate potent anti-diabetic effect.