Ethnomedicinal Plants for the Management of Diabetes Worldwide: A Systematic Review

Background: The increasing incidence of diabetes worldwide has urged researchers to explore novel antidiabetic agents from natural products. Ethnomedicinal field studies on diabetes have expanded across the globe, documenting large numbers of folk medicinal plants against diabetes. Nonetheless, a systematic review of these surveys has not been conducted so far. This study documents the medicinal plants traditionally used globally for managing diabetes. Methods: Key databases including Sciencedirect, Medline/PubMed, and Google Scholar were scrutinized. The Plant List and The International Plant Names Index (IPNI) were used to validate the scientific plant names. Results: 2004 traditionally used plants belonging to 1112 genera and 197 families were reported across 92 countries for the management of diabetes. Leguminosae (105 genera and 193 species), Compositae (97 genera and 188 species), and Lamiaceae (47 genera and 121 species) were the main plant families reported. Momordica charantia L., Syzygium cumini (L.) Skeels, Allium sativum L., Azadirachta indica A.Juss., Catharanthus roseus (L.) G.Don, Olea europaea L., Trigonella foenum-graecum L., Gymnema sylvestre (Retz.) R.Br. ex Sm., Aloe vera (L.) Burm.f., and Allium cepa L were the species mostly reported. Indeed, the antidiabetic properties of these main species have been evidenced by experimental studies. Several antidiabetic compounds acting via different mechanisms have been identified, including momordicoside, karaviloside, cucurbitacin, charantin, and charantoside from M. charantia, cuminoside from S. cumini, S-allyl cysteine sulfoxide from A. sativum, limonoids from A. indica, alkaloids including vindoline, vindolidine, vindolicine and vindolinine from C. roseus, oleuropein and oleanolic acid from O. europaea, flavone C-glycosides such as vicenin-1, isoschaftoside, and schaftoside from T. foenum-graecum seeds, gymnemosides, gymnemagenin, and pregnane glycosides from G. sylvestre, chysalodin from A. vera, and quercetin from A. cepa. Conclusion: This review is the first to provide a compiled list of traditional medicinal plants used worldwide against diabetes.