Comprehensive review on megastigmane glycosides: Sources, bioactivities, and 13C NMR spectroscopic data

Megastigmanes are structurally-diverse molecules that are widely distributed in nature and occurring mainly in plant kingdom. They are oxidative degradation products from β-carotenoids with C13 skeleton and their diversity has been attributed to different functionalization at the carbon atoms, as well as glycosylation pattern. The object of this review is to summarize the published literature on megastigmane glycosides regarding their sources, 13C NMR data and biological activities. This review covers the literature published between the first report that appeared in 1968 till May 2022. It combines about 357 megastigmane glycosides with their classification, sources, biological activities, and 13C NMR data. The biological activities of megastigmane glycosides have been reported, including anti-melanogenic, anti-inflammatory, neuroprotective, antioxidant, antitumor, antimicrobial, and hepatoprotective. Anti-melanogenic and hepatoprotective activities are the most promising reported bioactivities. Besides, biosynthetic pathways as well as chemotaxonomic significance are also discussed. The present review is expected to provide a comprehensive guide on this particular class of natural products.