Research progress on hydroxyl protection of iridoid glycosides

Iridoids, an important active ingredient, are widely distributed in varieties of Chinese herbal medicines and have varieties of pharmacological activities, such as anti-tumor, hypoglycemic, anti-inflammatory and so on, most of which exist in the form of glycosides in nature. However, its clinical application is limited by poor lipid solubility, low bioavailability and short half-life. It is necessary to optimize the structure of iridoids. It is hard to modify the hydroxyl groups at specific sites because iridoid glycosides are polyhydroxy compounds and very complex. In this paper, the words of ‘Iridoid glycosides’ and ‘Hydroxyl protection’ were used as the keywords, more than 200 articles from 1965 to 2021 were obtained from databases, such as CNKI, PubMed, Scifinder and so on. Finally, 60 articles were selected to summarize the hydroxyl protection of iridoid glycosides, which will provide a theoretical basis for their structural modification and stimulate their application potential in the field of drug research and development.