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We synthesized the naturally occurring carbasugar ampelomin A and its epimer from a common starting material. The enantiomerically pure starting material was obtained by base-catalyzed asymmetric Diels-Alder reaction of 3-hydroxy-2-pyrone and chiral acrylate. The total yield of ampelomin A was 14% in seven synthetic steps. The key step of the synthesis of ampelomin A was inversion of the stereochemistry at the C-6 position, which was achieved by stereoselective catalytic hydrogenation of the corresponding methylidene group. Further synthesis of the epimer was straightforward, because all stereogenic centers had already been introduced on the starting material; the total yield was 44% in four synthetic steps. Both the final products were obtained in pure form without contamination with undesired isomers. The reported (1)H NMR chemical shift of the C-7 methyl protons and the H-5axial coupling pattern of natural ampelomin A were inconsistent with those of our synthetic product. After careful comparison of the spectra and examination of the stable conformation obtained through MM2 calculations, we present revised NMR data for ampelomin A.

A new aaptamine-related alkaloid, 1,3-dioxolo [4,5- d] benzo [ de]-1,6-naphthyridine (methylenedioxyaaptamine, 1), was isolated from the organic extracts of the Bornean marine sponge Aaptos aaptos, together with a known aaptamine derivative, 8,9,9-trimethoxy-9 H-benzo [ de]-1,6-naphthyridine (2). The structure of compound 1 was elucidated by interpretation of its spectroscopic data. Two compounds were tested for their cytotoxic potentials against adult T-cell leukemia (ATL) cells, and compound 1 showed moderate cytotoxic potential.

A new manoalide-related sesterterpene, (4E,6E)-dehydro-25-O-methylmanoalide (1), was isolated from the organic extracts of the Bornean marine sponge Luffariella variabilis, together with the known compound (4E,6E)-dehydromanoalide (2). The structure of compound 1 was elucidated by interpretation of its spectroscopic data.

Through bioassay-guided isolation, five compounds with growth inhibitory activity on S1T, an adult T-cell leukemia (ATL) cell line, were isolated from the crude methanol extract of the aerial parts of Hyptis verticillata.

An ethanol extract of Quercus acuta trunk showed antibacterial activity against both gram-positive and gram-negative bacteria. The extract was sequentially partitioned with n-hexane, chloroform, ethyl acetate and water, and the highest activity was observed in the ethyl acetate fraction. Two active compounds isolated from the ethyl acetate fraction were 4,5-di-O-galloyl ( + )-protoquercitol and 3,5-di-O-galloyl protoquercitol, of which the former was the major active constituent. Gallic acid was also isolated from the same fraction, but it was not active.

A new manoalide-related sesterterpene, (4 E,6 E)-dehydro-25- O-methylmanoalide (1), was isolated from the organic extracts of the Bornean marine sponge Luffariella variabilis, together with the known compound (4 E,6 E)-dehydromanoalide (2). The structure of compound 1 was elucidated by interpretation of its spectroscopic data.

Further investigations of the secondary metabolites of a gorgonian Briareum sp., collected at Amami Oshima, Kagoshima Prefecture, have yielded 10 new briarane diterpenes, briarlides I-R (1-10). The structures were elucidated on the basis of spectral analysis.

The structure of furcatin, which was proposed to be p-vinylphenyl 6-O-apiosyl-(1→6)-β-D-glucoside, was revised to p-allylphenyl 6-O-[3-C-(hydroxymethyl)-β-D-erythrofuranosyl]-(1→6)-β-D-glucopyranoside by spectral and chemical results.