Ethnomedicinal Plants, Associated Indigenous Knowledge and Phytochemical Composition of Extracts with Significant in vitro Antidiabetic Activity

Abstract

Despite increasing popularity of ethnomedicinal plants in diabetes type 2 management nowadays, indigenous knowledge of their use is often not documented but rather passed on orally from generation to generation. Thus, the present study was designed to collect, analyze, document and generate useful information on ethnomedicinal plants used in management of Diabetes Mellitus Type 2 (DMT2). Materials and Methods: Data on ethnomedicinal use was collected using guided interviews, tour guides and information compared with literature search. Model in vitro enzyme inhibition assays were employed to investigate antidiabetic activity of the plants ethanol/water (60/40) extracts. Shinoda, Mayer Salkowski test and LC-MS/MS coupled with library search software’s was used to determine phytochemical composition of the most active extracts. Results: The ethnobotanical survey identified 30 medicinal plant species belonging to 18 plant families of which 14 (46.7)% are newly reported here for their claim as anti DMT2 medicine. Among the 30 plant species reported, 10 were very popular with informant consensus factor of ≥60%. The ethanolic/water (60/40) mixture extract of Zanthoxylum chalybeum, Xeroderris stuhlmannii, Syzygium cordatum and Eureiandra fasciculate showed the greatest in vitro antidiabetic activity, >70%. The present results shows that ethnomedicine plays an important part in the management of DMT2 with Zanthoxylum chalybeum, Xeroderris stuhlmannii, Syzygium cordatum and Eureiandra fasciculate being the most appraised ethnomedicinal plants. Standard chemical tests and LC-MS/MS analysis showed that the extracts consist of mostly C-glycosylated flavonoids and to lesser extent O-glycosylated flavonoids, alkaloids and phenolic acids. Conclusion: The generated results will be important in the prioritization of the plant species for polyherbal drug formulation and further investigation