Terpenoids in four Inula species from Bulgaria: Scientific paper

Phytochemical study of the chloroform extract of the aerial parts of Inula germanica L., I. ensifolia L., I. conyza (Griess.) DC. and I. salicina L. led to the identification of 33 terpenoids. β- and α-Amyrin, lupeol, taraxasterol, ψ-taraxasterol and their 3-O-acetates and 3-O-palmitates were identified by GC/MS. In addition, the structures of 3-O-palmitates of mainaladiol, arnidiol, faradiol and 16-hydroxylupeol were confirmed by NMR. ent-kaur-16-en-19-oic acid and its 15α-(3-methylpentanoyloxy) and 15α-(3-methylbutanoyloxy) deriva­tives were isolated from I. conyza. Ten closely related sesquiterpene lactones (germacranolides and melampolides) were found in I. germanica and their struc­tural identification was performed by spectral analyses. I. ensifolia and I. salicina were free of sesquiterpene lactones and diterpenoids. All triterpenoids and diterpenoids, grazielia acid, desacetylovatifolinan, and 8-(2-methyl­butan­oyloxy)-1(10),4,11(13)-germacrutrien-6,12-olide-14-oic acid are described for the first time in the studied species. Principal component analysis (PCA) was used to find a relationship between investigated up to now Inula species, growing in Bulgaria.