Chapter 7 - Nonhalogenated Heterotricyclic Sesquiterpenes From Marine Origin I: Fused Systems

Abstract

Abstract Heterocyclic sesquiterpenes (HSs) make up a large class of natural sesquiterpenes, with over 500 representatives. The current review provides a comprehensive survey of the nonhalogenated heterotricyclic sesquiterpenes (NH-HTSQTs) that have been isolated from the marine area. The records were published in the literature from 1968 to early 2015. Have been considered the heterotricyclic terpenoids, derived from monocyclic or bicyclic sesquiterpenes, through a ring closure of lactones, epoxides, furans, ethers. A total of 164 compounds and 137 references are recorded for the fused systems derived from the cadinane, eremophilane, drimane, nardosinane, microcionin, furodysin, and related sesquiterpenoids collected in the first part of this comprehensive review. These secondary metabolites are organized in sections according to structural families of compounds. Comments on structural characterization, biogenesis, and biological activity have also been included. While compared with the carbocyclic nonhalogenated sesquiterpenes, the NH-HTSs often exhibit different biological and pharmacological activities. They have antifeedant, anti-infective, immunosuppressive, and cytotoxic properties among others. The classification, biosynthesis, and bioactivity of NH-HTSQTs are discussed in detail.