Natural sesquiterpenoids

Sesquiterpene Lactones-Based Classification of the Family Asteraceae Using Neural Networks and k-Nearest Neighbors

“…Another possible reason for misclassification with any model might be that the new instances, which are to be tested, lie far away from the prediction space. Although the models presented herein are aimed at a specific class of secondary metabolites, i.e., STLs, the problem is still present since several novel STLs are reported each year, − some of them with rather unusual structures, including for example dimers . This was what we examined in turn.…”

“…Data Sets. The structures of the 921 STLs and the information concerning their taxonomic origin were taken from comprehensive surveys published in the literature. ,− The taxa (tribes and genera) presented herein are in accordance to the division made by Bremer . This information was used to assign all chemical structures to their corresponding taxa.…”

A guaianolide-type sesquiterpene lactone

“…The guaianolides are one of the largest groups of sesquiterpene lactones isolated from higher plants (Roberts & Bryson, 1984;Fraga, 1985Fraga, , 1986Fraga, , 1987Fraga, , 1988Fraga, , 1990Fraga, , 1992Fraga, , 1993Fraga, , 1994Fraga, , 1995Fraga, , 1996Fraga, , 1997Fraga, , 1998Fraga, , 1999Fraga, , 2000Fraga, , 2001 and they are frequently cited as allelopathic agents, especially in plants of the family Compositae. These sesquiterpene lactones have attracted significant interest due to their biological properties, particularly their antitumor and cytotoxic activities (Bruno et al, 2005;Dirsch et al, 2001;Lee et al, 2001;Rodríguez et al, 1976).…”

Purpurolide A, 5/5/5 Spirocyclic Sesquiterpene Lactone in Nature from the Endophytic Fungus Penicillium purpurogenum

“…Bergamotane sesquiterpenes, bearing a bridged 6/4 bicyclic ring incorporated with an isopentyl unit, are naturally occurring in plants and fungi. − A new class of polyoxygenated bergamotanes with notable features inspired by a 6/4/5/5 tetracyclic ring system is very rare in nature. All examples of the polycyclic bergamotanes only derived from fungi include expansolides A–D, − decipienolides A and B, sporulaminals A and B, donacinolides A and B, and massarinolin A. , Interestingly, these metabolites normally occurred as inseparable tautomeric mixtures epimerized in the spirolactone ring, although massarinolin A has been isolated as a single compound due to the structure stability enhancement by the OH-5.…”