Cytotoxic Cardiac Glycoside Constituents of Vallaris glabra Leaves.

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.

Anti-inflammatory 12,20-Epoxypregnane and 11,12-seco-Pregnane Glycosides from the Stems of Hoya kerrii.

Five 12,20-epoxypregnane glycosides (1-3, 5, and 6) and two 11,12-seco-pregnane glycosides (4 and 7) with spirodilactone motifs, as well as spirodilactone cleavage products 8 and 9, were isolated from the stems of Hoya kerrii. The relative configurations of the three related skeletons were supported by ROESY experiments and X-ray crystallographic analyses. The isolates were evaluated for their anti-inflammatory activity based on the inhibition of NO production in RAW264.

Eriosema chinense: a rich source of antimicrobial and antioxidant flavonoids.

Six prenylated flavonoids, (2R,3S)-3,5,4'-trihydroxy-6″-6″dimethylpyrano(2″,3″:7,6)-8-(3″', 3″'-dimethylallyl)flavanone, (2R,3S)-3,5,2'-trihydroxy-4'-methoxy-6″,6″-dimethylpyrano(2″,3″:7,6)-8-(3″',3″'-dimethylallyl)flavanone, (2R,3R)-3,5,2',4'-tetrahydroxy-6″,6″-dimethylpyrano(2″,3″:7,6)-8-(3″',3″'-dimethylallyl)flavanone, 3,5,2',4'-tetrahydroxy-6″,6″-dimethylpyrano(2″,3″:7,6)-8-(3″',3″'-dimethylallyl)flavone, (2R,3R,2″'R)-3,5,2″'-trihydroxy-4'-methoxy-6″,6″-dimethylpyrano(2″,3″:7,6)-8-(3″'-methylbut-3″'-enyl)flavanone, (2R,3R)-3,5-dihydroxy-4'-methoxy-6″,6″-dimethylpyrano(2″,3″:7,6)-8-(2″',3″'-epoxy-3″'-methyl butyl)flavanone, an isoflavone, 6,7-dimethoxy-5,2',4'-trihydroxyisoflavone, and octaeicosanyl-trans-p-coumarate together with 12 known compounds, were isolated from roots of Eriosema chinense. This structural elucidation was determined by spectroscopic methods. Several isolates and derivatives were evaluated for their antimicrobial and antioxidant activities.

Antiplasmodial sesquiterpene alkaloids from the roots of Maytenus mekongensis.

Eight new sesquiterpene alkaloids (1-8) and four known sesquiterpene alkaloids (9-12) have been isolated from the roots of Maytenus mekongensis. Structures were determined using extensive spectroscopic methods. The relative configuration of 7-epi-mekongensine (2) was established by single-crystal X-ray crystallographic analysis.

Cytotoxic and antimycobacterial prenylated flavonoids from the roots of Eriosema chinense.

Eight new prenylated flavonoids, khonklonginols A-H (1-8), together with six known compounds including five flavonoids, lupinifolinol (9), dehydrolupinifolinol (10), flemichin D (11), eriosemaone A (12), and lupinifolin (13), and one lignan, yangambin (14), have been isolated from hexane and dichloromethane extracts of the roots of Eriosema chinense. The structures of 1-8 were elucidated by spectroscopic methods. The compounds were evaluated for cytotoxic activity against the small-cell lung (NCI-H187) and oral epidermal carcinoma (KB) human cell lines as well as for antimycobacterial activity against Mycobacterium tuberculosis H37Ra.

19-Nor- and 18,20-epoxy-cardenolides from the leaves of Calotropis gigantea.

Two new cardenolides (1 and 2) along with 12 known compounds were isolated from the dichloromethane extract of the leaves of Calotropis gigantea. The structural elucidation was accomplished by spectroscopic methods. Some of the isolates were evaluated for cytotoxic activity against KB, BC, and NCI-H187 cancer cell lines, and all cardenolides tested were found to possess strong inhibitory effects.