Reactions of alpha-ketols and other 21-hydroxy steroids with phosgene. IV. Formation of 20-chloro-17,20-cyclic carbonates from 17 alpha-hydroxy-20-ones

Asimitrin and 4-hydroxytrilobin, new bioactive annonaceous acetogenins from the seeds of Asimina triloba possessing a bis-tetrahydrofuran ring

Bioactivity-directed fractionation of the seeds of Asimina triloba resulted in the isolation of asimitrin (1) and 4-hydroxytrilobin (2). Compound 1 represents an adjacent ring-hydroxylated bis-tetrahydrofuran (THF) acetogenin. Compound 2 has an adjacent bis-THF ring with two flanking hydroxyl groups and a alpha,beta-unsaturated gamma-lactone with a 4-hydroxyl group. Compounds 1 and 2 showed cytotoxic selectivity, with 100-10 000 times the potency of adriamycin against prostate adenocarcinoma (PC-3) and colon adenocarcinoma (HT-29) cell lines.

New cytotoxic steroids from the Indian Ocean sponge Axinella cf. bidderi

Four new sterols have been isolated from the marine sponge Axinella cf. bidderi, 17alpha-hydroxy-22,23-epoxy-24-methylcholest-5-en-3beta-ol (1) and 17alpha-hydroxy-22,23-epoxycholest-5-en-3beta-ol (2), together with 3 and 4, which possess respectively the cholestene and the cholestane skeleton with a cyclic enol ether linkage between C-18 and C-22. The structures were elucidated using spectroscopic data. The in vitro activity was evaluated against prostate, ovary, pancreas, colon, and lung cell lines.

Novel stereoselective synthesis of 7beta-methyl-substituted 5-androstene derivatives

The 7beta-methyl-5-androstene derivatives 11a-c were prepared in good yield with high stereoselectivities starting from 3beta-acetoxyandrost-5-en-17-one 4. The addition of methylmagnesium iodide to the 7-carbonyl group of 7a-c gave, after hydrolysis, two isomers 9a-c and 10a-c, which were stereoselectively deoxygenated by means of an ionic hydrogenation to afford the compounds 11a-c.

New saponins from the starfish Certonardoa semiregularis

Ten new saponins designated as certonardosides A-J (1-5, 7-11) and the known halityloside D (6) were isolated from the brine shrimp active fraction of the MeOH extract of the starfish Certonardoa semiregularis. The structures were determined on the basis of spectral analysis and chemical manipulation. The compounds were evaluated for antiviral activity against HIV, HSV, CoxB, EMCV, and VSV and displayed insignificant activity within the range of noncytotoxic concentrations.

Polyhydroxylated sterols from the octocoral Dendronephthya gigantea

Two new polyhydroxylated sterols, dendronesterols A (1) and B (2), have been isolated from the octocoral Dendronephthya gigantea. The structures of 1 and 2 were proposed on the basis of extensive NMR experiments. Compound 2 was found to be weakly cytotoxic toward L1210 cells.

Isolation of 20 glycosides from the starfish Henricia downeyae, collected in the Gulf of Mexico

Thirteen new (1-13) and seven known (14-20) steroid glycosides were isolated from Henricia downeyae, collected from the offshore waters of the northern Gulf of Mexico. Ethanolic extracts of these starfish caused growth inhibition in bacteria and fungi, potent antifouling activity against barnacle and bryozoan larvae, and feeding deterrent activity against a marine fish. The known compounds are typical glycosides found in several species of the family Echinasteridae, i.e., Echinaster sp. and Henricia laeviuscola. One of the new compounds belongs to this group, whereas the remaining 12 new compounds represent a novel series of steroid glycosides which have aglycons with structural similarities to the "asterosaponins". They possess a delta 9(11) 3 beta, 6 alpha-dihydroxysteroidal aglycon with 23-oxo or 22,23-epoxy functionalities and often a 20-hydroxyl group in the side chain. The sulfate is located at C-6 and the saccharide moiety at C-3, in contrast with the asterosaponins which have the sulfate at C-3 and the oligosaccaride moiety at C-6. All the new compounds contain a glucuronic acid unit, which is uncommon among steroid glycosides from echinoderms. The structures of the new compounds, isolated in amounts ranging from 3.4 to 0.9 mg, were determined by interpretation of their spectral data and by comparison with spectral data of known compounds.