Biologically active alkylated coumarins from Kayea assamica.

Four coumarin derivatives, theraphins A (1), B (2), C (3), and D (4), along with three known xanthones, 2-hydroxyxanthone, 1,7-dihydroxyxanthone, and 5-hydroxy-1-methoxyxanthone, were isolated from the bark of Kayea assamica (Clusiaceae) native to Myanmar. Their structures were determined using spectroscopic and chemical techniques. The absolute configuration of 1 was established by the modified Mosher ester method.

Flavonoid constituents from Eupatorium altissimum L. (Compositae).

An aqueous ethanol extract of Eupatorium altissimum L. (Compositae) showed confirmed activity in the P-388 lymphocytic leukemia assay in mice, and the chloroform solubles showed both cytotoxic activity in the 9KB carcinoma of the nasopharynx cell culture assay and antitumor activity in the P-388 lymphocytic leukemia assay. Two flavones, eupatorin and 5-hydroxy-3',4',6,7-tetramethoxyflavone, were isolated and identified.

Sinoacutine from Glaucium contortuplicatum Boiss.

A phytochemical investigation of Glaucium contortuplicatum Boiss. (Papaveraceae) resulted in the isolation of sinoacutine from this plant for the first time. Spectral evidence for the identity of the isolated compound as sinoacutine is presented.

Isolation of flindersiamine, isoflindersiamine, and a new alkaloid, heliparvifoline, from Helietta parvifolia (Rutaceae).

A phytochemical investigation of the leaves and twigs of Helietta parvifolia (Rutaceae) resulted in the isolation of heliparvifoline, a new furoquinoline alkaloid, in addition to the known bases flindersiamine and isoflindersiamine.

Microbial transformation of aspidospermine.

Thirty actinomycetes were isolated from soil samples and screened for their ability to modify the structure of aspidospermine. One actinomycete culture converted aspidospermine into O-demethylaspidospermine but failed to modify N-deacetylaspidospermine, N-ethyl-N-deacetylaspidospermine, 7-methoxyindole, and 7-methoxytryptophan.

Cytotoxic principles of Parquetina nigrescens (Afzel.) Bullock (Asclepiadaceae).

Systematic fractionation of the cytotoxic extracts of the roots of Parquetina nigrescens (Afzel.) Bullock (Asclepiadaceae) on silica gel column chromatography led to the isolation of three cardenolides: cymarin, strophanthidin, and a strophanthidin glycoside (XS-89). Also isolated during the investigation were beta-sitosterol-beta-D-glucoside, a mixture of alpha- and beta-amyrins, a mixture of alkanols, and a mixture of plant sterols.

Potential anticancer agents II: antitumor and cytotoxic lignans from Linum album (Linaceae).

A phytochemical study of Linum album (Linaceae), guided by bioassay with the 9KB cell culture, resulted in the isolation of podophyllotoxin and a new lignan, 3'-demethylpodophyllotoxin; alpha-and beta-peltatins were identified by comparative TLC.