Chemistry and Biodiversity

Texto completo: acesso restrito. p.1463–1470Four new (9βH)-lanostanes, i.e., (9βH)-3β-acetoxylanosta-7,24-diene, (9βH)-3-oxolanosta-7,24-diene, (9βH,24R)-3β-acetoxy-24-hydroxylanosta-7,25-diene, and (9βH,24S)-3β-acetoxy-24-hydroxylanosta-7,25-diene, two new lanostanes, i.e., (24R)-3β-acetoxy-24-hydroxylanosta-8,25-diene and (24S)-3β-acetoxy-24-hydroxylanosta-8,25-diene, and two known lanostanes, i.e., 3β-acetoxylanosta-8,24-diene and 3-oxolanosta-8,24-diene, were obtained from a new Mikania species (Asteraceae) besides pentacyclic triterpenes, steroids, and diterpenes. The structures of the compounds were determined by spectroscopic methods. This is the second study about acetyl-lanosterols from higher plants. Moreover, (9βH)-lanostanes are very rare metabolites from dicotyledone angiosperms. The occurrence of these terpenes together in the same plant makes the species a good source for lanostane- and (9βH)-lanostane-biosynthesis studies