The Promising Role of Plant Tannins as Bioactive Antidiabetic Agents

Background: Plant tannins are polyphenolic substances with various molecular weights and a variable complexity. Due to the beneficial effects for controlling chronic disorders particularly diabetes mellitus, this class of secondary metabolites has gained more interest in the recent years. Objective: We aimed through this review to collect, analyze and discuss all available information related to the antidiabetic effect of isolated tannins (including both condensed and hydrolysable varieties) and tannin-rich plants as well as the possible mechanisms of action involved in this antidiabetic activity. Methods and Results: Our bibliographic research was conducted to gather more than 41 medicinal plants containing tannins and 19 isolated tannins and tannin-rich crud extracts which were revealed to possess glucose lowering effect according to pharmacological studies. Conclusion: Hence, according to findings of the present review, tannins could be useful for prevention and management of diabetes mellitus and its associated complications and these natural products could be promising compounds for the discovery of new hypoglycemic agents.