New (9βH)‐Lanostanes and Lanostanes from Mikania aff. jeffreyi (Asteraceae)

Abstract

Four new (9betaH)-lanostanes, i.e., (9betaH)-3beta-acetoxylanosta-7,24-diene, (9betaH)-3-oxolanosta-7,24-diene, (9betaH,24R)-3beta-acetoxy-24-hydroxylanosta-7,25-diene, and (9betaH,24S)-3beta-acetoxy-24-hydroxylanosta-7,25-diene, two new lanostanes, i.e., (24R)-3beta-acetoxy-24-hydroxylanosta-8,25-diene and (24S)-3beta-acetoxy-24-hydroxylanosta-8,25-diene, and two known lanostanes, i.e., 3beta-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, (9betaH)-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 (9betaH)-lanostane-biosynthesis studies.

Biosynthesis of Cholesterol and Other Sterols

“…( 90 ) These results show that only small changes in the active site topography of these enzymes are required to fashion a fungal/animal synthase from a plant synthase. Lanosterol, parkeol, and lanostane derivatives with the 9βH-sterochemistry have recently been found to occur naturally in plants, 12 , 91 raising questions of their biosynthetic origin, that is, from preformed cycloartenol. Detailed investigations of the steric and electrostatic effects of conserved aromatic residues through site-directed mutagenesis experiments have revealed cation−π interactions that may influence the product outcome.…”

Euphane Triterpenes from the Bark of Broussonetia papyrifera

“…Compounds 3 and 4 were isolated as a mixture due to their strong structural similarity. It is noteworthy that lanostane derivatives with the same substitution pattern have also been obtained as 24-epimer mixtures [10].…”

Ceramides and cytotoxic constituents from Ficus glumosa Del. (Moraceae)

“…The crude organic extract was subjected to repeated columns chromatography yielding two new ceramides (1, 2) together with twenty one known compounds namely lanosta-7,24-dien-3-one (3), 8 lanosta-8,24-dien-3-one (4), 8 β-amyrine (5), 9 lupeol (6), 9 6-prenylpinocembrin (7), 10 bergapten (8), 11 chiricanine A (9), 12 genistein (10), 13 wighteone (11), 13 6-prenylapigenin (12), 14 24 The ceramide core was confirmed by long-range correlations exhibited on the HMBC spectrum between the proton at d H 7.38 and the carbonyl at d C 175.5. Moreover, the proton of oxymethine group at d H 3.47 (H-4) correlated with the carbons at d C 61.3 (C-1), 51.8 (C-2), and 75.8 (C-3) which matched with a trihydroxylamine-sphingosine in the phytoceramide skeleton.…”