Norsesquiterpenoids from terrestrial and marine organisms: Chemistry, activity and possible biosynthetic pathways (1963–2024)

Norsesquiterpenoids are naturally occurring carbon-reduced derivatives of sesquiterpenoids that are biosynthesised according to the isoprene rule of Ruzicka. Norsesquiterpenoids have attracted considerable interest from chemists and biologists because of their distinct structural characteristics and biological activity. Numerous norsesquiterpenoids with novel carbon skeletons have been reported. Their diverse structures are linked to various potent biological activities, including anti-inflammatory, anti-microbial, anti-viral, anti-oxidant, anti-Alzheimer, hypoglycaemic and cytotoxic. This review provides a comprehensive summary of 693 natural norsesquiterpenoids discovered in plants, fungi, marine organisms and microorganisms between 1963 and 2024, focussing on their identification, bioactivities and biosynthesis. The review also provides a brief overview of the biosynthesis of norsesquiterpenoids. In addition, several recommendations are proposed for future research. This review aims to serve as a useful reference for the development of natural norsesquiterpenoids and to provide beneficial guidance for the application of these health-related compounds and their source plants in pharmaceuticals, functional foods, cosmetics and agriculture.