Phytochemical constituents, antioxidant and antidiabetic activities of different extracts of the leaves, stem and root barks of Alstonia boonei: an in vitro and in silico study

This study investigated the antidiabetic and antioxidant activities of the extracts from three parts of Alstonia boonei. Sequential extraction of leaves, stem and root bark samples was done with the solvents of increasing polarity and these extracts were assayed for total phenolic content and in vitro antioxidant and antidiabetic activities using different experimental models. The electron donating, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide radical scavenging activities of all the extracts were investigated in this study. The ability of these extracts to inhibit α-glucosidase and α-amylase was also examined in vitro. The ethanol extract of leaves showed the highest total phenolic content compared to other extracts. All extracts showed free radical scavenging abilities in different experimental models. The ethanol and aqueous extracts significantly (p < 0.05) inhibited the activities of key enzymes linked to type 2 diabetes. GC-MS analysis of the extracts from different plant parts revealed the presence of sterols, aromatics, aliphatic acids and esters. These compounds showed a high binding affinity with α-glucosidase and α-amylase enzymes under molecular docking studies. Data of this study suggest that the different parts of A. boonei, especially the ethanol and aqueous extracts of leaves, possess potent antioxidant and diabetes related enzymes inhibitory activities that could be further exploited in the development of novel antidiabetic medicines.