In vitro Antioxidant and Antidiabetic Potential of Crude Extracts from the Seed Coat and Fruit Pulp of Strychnos madagascariensis

Diabetes mellitus remains a global health issue despite the advance in orthodox medicine. This study investigated the in vitro antioxidant and antidiabetic potential of crude extracts from the seed coat and pulp of Strychnos madagascariensis. The phytochemical screening was carried out using standard protocols. Different extracts were prepared from the fruit parts by maceration using methanol, n-hexane, ethyl acetate, and water for antioxidant and antidiabetic assays, and their percentage yield was calculated. The antioxidant potential of the extracts was determined using 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 2’2- diphenyl-1-picrylhydrazyl (DPPH). Antidiabetic activities of the extracts were investigated using α-amylase, α-glucosidase, and pancreatic lipase assays. Terpenoids, alkaloids and cardiac glycosides were present in both the fruit parts. However, saponin present in the fruit pulp was absent in the seed coat (testa). The percentage yields are as follows; water > ethyl acetate > hexane > methanol (seed coat) and methanol > water > ethyl acetate > hexane (fruit pulp), respectively. The crude extracts scavenged ABTS and DPPH radicals in different degrees. The aqueous extract of the pulp and seed coat (testa) showed significant (P < 0.05) higher scavenging activity against ABTS (IC₅₀; 0.012 and 0.006 mg/ml) and DPPH (IC₅₀; 0.06 mg/ml and 0.064 mg/ml) radicals than other extracts. The crude extracts inhibited α-amylase, α-glucosidase, and pancreatic lipase. The aqueous and methanol extracts of the fruit parts showed better amylase inhibitory activity than other extracts. The aqueous extract of the seed coat (IC₅₀; 0.0785 mg/ml) showed the highest glucosidase inhibitory activity. In addition, methanol extract of the seed coat (IC₅₀; 0.069 mg/ml) exhibited the highest inhibitory activity on pancreatic lipase compared to the extracts in other solvents. Hence, the aqueous and methanol crude extracts of Strychnos madagascariensis seed coat and fruit pulp could be used in the preparation of nutraceutical products for managing diabetic mellitus.