Two 15b b-hydroxycardenolides (1,2) and a 16a a-hydroxycalactinic acid methyl ester (3) along with eleven known compounds including 16a a-hydroxycalotropagenin, coroglaucigenin, 16a a-hydroxycalotropin, calactinic acid, calotoxin, 6 -O-(E-4-hydroxycinnamoyl)desglucouzarin, 12b b-hydroxycoroglaucigenin, frugoside, calotropagenin, 9,12,13-trihydroxyoctadeca-10(E),15(Z)-dienoic acid and R-(؊ ؊)-mevalonolactone were isolated from the polar fraction of the CH 2 Cl 2 extract, and n-BuOH extract of the leaves of this plant. The isolated compounds were evaluated for their inhibitory activities against a panel of cell lines.Key words Calotropis gigantea; 15b-hydroxycardenolide; 16a-hydroxycalactinic acid methyl ester Chem. Pharm. Bull. 58(5) 725-728 (2010)

Thirteen cardenolide glycosides (1-13) were isolated from the CHCl and MeOH extracts of Vallaris glabra leaves. The structures of the new compounds (2-13) were identified by spectroscopic methods, with the absolute configurations of the sugar moieties determined by acid hydrolysis. All compounds were evaluated for their cytotoxic activity against human cervix adenocarcinoma, lung carcinoma, and colorectal adenocarcinoma cell lines. The two most potent compounds [2'-O-acetylacoschimperoside P (1) and oleandrigenin-3-O-α-l-2'-O-acetylvallaropyranoside (2)] exhibited IC values in the range of 0.03-0.07 μM.

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Sixteen compounds including dihydroxy prenylfuranocoumarins/3-hydroxy-3-methylglutaric acid conjugates and dihydroxy prenylfuranocoumarins/3-hydroxy-3-methylglutaric acid/1-O-flavonyl-β-d-glucopyranoside conjugates, together with other dihydroxyprenylfuranocoumarins conjugates, were isolated from the ethyl acetate extract of the fruit peels of Citrus hystrix. Some of the isolates were evaluated for their cholinesterase inhibitory activity, but only one compound possessing a 3-O-β-d-glucopyranosyl-3,5,7,4'-tetrahydroxy-6,8,3'-trimethoxyflavonol nucleus in the prenylfuranocoumarin-HMGA conjugate showed strong activity.