iridoids
Iridoids are a class of monoterpenoid secondary metabolites typically found in plants as glycosides. They are based on an iridoid skeleton, a cyclopent[2]pyran ring system that is highly oxygenated and often substituted with various hydroxyl, carbonyl, and glycosyl groups. Most iridoids occur as iridoid glycosides, where the aglycone is linked to one or more sugar units.
Biosynthesis and structure: Iridoids are derived from geraniol via the mevalonate or MEP pathway, followed by
Distribution and sources: Iridoids are widespread in higher plants, particularly in families such as Rubiaceae and
Biological roles and uses: They commonly function as defense compounds against herbivores and pathogens. Pharmacologically, iridoids
Examples: Aucubin, catalpol, geniposide, loganin, and the aglycone genipin are well-known iridoids.