From a MeOH extract of Psiadia trinerviu, seven phenolic compounds were isolated by gel filtration and reversed-phase chromatography. Six of them are known compounds, namely 3,4-di-O-caffeoylquinic acid (2), 3,5-di-0-caffeoylquinic acid (3), caffeic acid, and three 3-methoxyflavonoids. Compound 1 is a 3,4-di-0 -caffeoyl derivative of (lS,3R,4R,5R)-I ,3,4,5-tetrahydroxycyclohexanecarboxylic acid, a novel stereoisomer of (-)-quinic acid. Following hydrolytic treatment of the MeOH extract, ethyl 3-0-caffeoylquinate (4), ethyl 3,4-di-O-caffcoylquinate (5), and ethyl 3,5-0 -caffeoylquinate (6) were isolated. The latter three compounds are artifacts. The configuration of 1-3 was established by NMR and CD (exciton chirality method).
Introduction.
-Psiudiu trinerviu WILLD (Asteraceae) is an endemic species of the Mascarene Islands [l]. It was used as a vulnerary and expectorant for the treatment of asthma in the folk medicine of Mauritius [2] [3]. Several diterpenes [ 4 6 ] and some terpenes in the essential oil [7] of this plant were reported prior to our own investigations. A phytochemical analysis of the CH,Cl, extract and the hydrolyzed MeOH extract of P . trinerviu afforded a series of 3-methylflavonols, some of which showed antimicrobial activities against the plant pathogenic fungus Cladosporium cucumerinum and the grampositive bacterium Bacillus cereus . Subsequently, we focused on the composition of the MeOH extract before and after hydrolytic treatment and report here on the isolation and structure determination of chlorogenic acid ( = 3-0 -caffeoylquinic acid) derivatives from these extracts.
Results and
Discussion. -Dried leaves of Psiudiu trinerviu collected in Mauritius were ground and extracted successively with petroleum ether, CH,Cl,, and MeOH. Com-I HO 1 Hd 2 R' = R3 = H, R' = caffeoyl