Advances in triterpenoid research, 1990–1994

Two new compounds were isolated from the stem and twigs of Ribes fasciculatum var. chinense and their structures were identified to be threo-(7S,8R)-1-(4-hydroxyphenyl)-2-[4-(E)-propenylphenoxy]-propan-1-ol (1), and 5,4'-dihydroxy-7-methoxyflavone-3-O-[alpha-L-rhamnopyranosyl(1-->3)-O-alpha-L-rhamnopyranosyl(1-->6)-O-beta-D-glucopyranoside] (2). With nine other known components, they were tested on inhibitory activity against nuclear factor of activated T cells (NFAT) transcription factor. Compound 1 showed a potent inhibitory activity (IC50=15.6 microM), while compounds 4, 5 and 9 showed moderate inhibitory activity (IC50 22.4, 24.5 and 25.7 microM, respectively).

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New Inhibitor against Nuclear Factor of Activated T Cells Transcription from Ribes fasciculatum var. chinense

Two new pentacyclic triterpene esters, peltastine A [3beta-[5-phenyl-(2E,4E)-penta-2,4-dienoyloxy]-urs-12-ene] and peltastine B [3beta-[5-phenyl-(2E,4E)-penta-2,4-dienoyloxy]-lup-20(29)-ene], have been isolated from the stem of Peltastes peltatus (Vell.) Woodson along with the previously reported beta-amyrin juarezate [3-[5-phenyl-(2E,4E)-penta-2,4-dienoyloxy]-olean-12-ene]. The structures of these compounds were established by MS, 1D- and 2D-NMR experiments as well as by chemical degradation.

Pentacyclic triterpene 5‐phenylpenta‐2,4‐dienoyl esters from Peltastes peltatus (Vell.) Woodson

New lupane-type triterpenoids with 5(6) double bond were prepared using the method of partial demethylation on carbon C-4. Hydroboration of the double bond led to 6α-hydroxy derivative. By the oxidation and following reduction of 6α-hydroxy derivative the 6-oxo and 6β-hydroxy derivatives were prepared. A new method for selective oxidation of secondary hydroxy group in the presence of primary hydroxy group was performed. The conformation of ring A of new lupane-type 3-oxo derivatives with a substituent on ring B was elucidated on the bases of 1 H and 13 C NMR spectra and molecular modelling.

Amit Basak

Papers

Querspicatins A and B, two pentacyclic triterpenes from Quercus spicata