Iridoids
Structure of Iridoids: Derived from monoterpenes with a cyclopentane[c]pyran ring, often occurring as glycosides hydrolyzed to release active aglycones.
Plant Functions: Serve as defense compounds (bitter and toxic), aid in signaling, and deter herbivores and pathogens.
Other Terpenoids
Structure: Derived from isoprene units (C5), forming diverse structures such as monoterpenes, sesquiterpenes, and diterpenes.
Plant Roles:
Ecological Interactions: Attract pollinators, repel herbivores, or act as chemical signals.
Protection: Many exhibit antimicrobial, antifungal, or anti-inflammatory properties.
Pharmacological Importance: Used in traditional medicine, food flavoring, and as precursors for pharmaceuticals.
Naphthoquinones
Structure: Naphthalene ring with two carbonyl groups; conjugation often gives bright colors (yellow to red).
Biological Roles:
Function as pigments.
Defensive properties include generating reactive oxygen species and disrupting cellular processes in predators or pathogens.
Pharmacological Potential: Possess antimicrobial, antiviral, and anticancer activities, making them valuable for therapeutic applications.