Iridoid for drug discovery: Structural modifications and bioactivity studies

Iridoid glycosides are a class of chemical structures with various pharmacological activities and have excellent research potential. However, the poor stability, water solubility, and oral bioavailability limit their practical application and clinical research. In this review, we systematically summarize the structural modifications of iridoid glycosides and attempt to demonstrate the structure-activity relationship between chemical modifications on iridoid skeleton and glycosidic bond, noting that some derivatives exhibit satisfactory pharmacological activities. This review aims to provide valuable assistance for further research and clinical application of derivatives, to provide ideas for the design and synthesis of novel iridoid glycosides, and to provide a research basis for developing new drugs with higher activity in the future.