Iridoid glycosides from the Genus Gentiana (Gentianaceae) and their Chemotaxonomic Sense

The genus Gentiana is one of the largest genera in the Gentianaceae family. Many Gentiana species have been scientifically investigated for their chemical constituents and chemotaxonomic sense. To date, more than 500 chemical compounds were isolated from Gentiana plant. Several researchers have reviewed the secondary metabolites and their bioactivities of Gentiana plants. However, a survey on iridoid glycosides and their chemotaxonomic sense of the genus Gentiana are unavailable. Iridoid glycosides are the major chemicals isolated from Gentiana spp., which serve as potential chemotaxonomic markers to differentiate Gentiana species. Herein, the review systematically summarizes the scaffolds of the iridoids reported according to the biosynthetic pathway of natural iridoid glycosides. Furthermore, the taxonomy of Gentiana and chemotaxonomic sense of iridoid glycosides in the genus Gentiana were surveyed.