An In-vitro Antioxidant and Antidiabetic Evaluation of Traditional Medicinal Plants of Botswana

The present study was aimed at the in-vitro analysis of the antioxidant and antidiabetic potential of the methanol extracts of four perennial plants which are indigenous to Botswana and further to investigate whether their antihyperglycemic effects are working through the antioxidant system. The plants used in this study were the aerial parts of Ocimum gratissimum, corms of Hypoxis hemerocallidea, aerial parts of Momordica balsamina and the leaves and stems of Lippiascaberrima. The extracts were prepared in 70% methanol and they were labeled as MEOG, MEHHC, and MEMB, MELS (l) and MELS (s) respectively. All the four plant extracts showed a notable antioxidant and antidiabetic activity, the most potent one being H. hemerocallidea and the least potent being L. scaberrima stems. The total antioxidant status was evaluated by DPPH, ABTS and TBA assays. Total phenolic content was determined for each extract and converted to mg of gallic acid equivalents/g of dry extract (mg GAE/g).The crude methanol extracts showed many components with high radical scavenging activity in the TLC-DPPH bioautogram. The antidiabetic potential was determined by evaluating the inhibition of the extracts on α-amylase activity, and the results indicated that MEHHC showed the highest effect followed by MEMB, MEOG MELS (l) and MELS(s). The results obtained in the present investigations indicated that the extracts used in this study have bioactive compounds with antioxidant and antidiabetic properties.