Thirteen new metabolites, melophlins C-O (1-13), were identified from the marine sponge Melophlus sarassinorum. Compounds 1-13 represent tetramic acid derivatives that differ with regard to the nature of their alkyl side chains. The structures of the new compounds were elucidated on the basis of comprehensive spectral analysis (1H, 13C, 1H-1H COSY, HMQC, and HMBC NMR, as well as low- and high-resolution ESIMS and EIMS). The absolute configurations of 1, 8, 10, 11, 12, and 13 were determined by ESI LC/MS analysis of chiral derivatives obtained upon oxidation and hydrolysis of the respective parent compounds. Melophlin C (1) displayed pronounced antibacterial activity against Bacillus subtilisand Staphylococcus aureus, together with antifungal activity against Candida albicans.

Six new 4-phenyl-3,4-dihydroquinolone derivatives (1-6) along with the related aflaquinolone A (7) were isolated and identified from the cultures of Aspergillus nidulans MA-143, an endophytic fungus obtained from the fresh leaves of the marine mangrove plant Rhizophora stylosa. Their structures including absolute configurations were determined by spectroscopic analysis and electronic circular dichroism experiments, and the structure of compound 1 was confirmed by single-crystal X-ray crystallographic analysis. In bioscreening experiments, none of the isolated compounds showed potent antibacterial or cytotoxic activity. However, compounds 2, 3, and 7 exhibited lethality against brine shrimp (Artemia salina), with LD50 values of 7.1, 4.5, and 5.5 μM, respectively.

Endophytic fungi are a large group of microorganisms which were defined as fungi colonizing healthy plant tissue without causing overt symptoms in or apparent injury to the host. Endophytes have been proven to be a well-established source for structurally diverse and biologically active secondary metabolites.2-4) Marine mangrove plants were proven to be a rich source of endophytic fungi. Many secondary metabolites with novel structures and biological activities have been characterized from mangrove-derived endophytic fungi. [5][6][7][8] In the course of our ongoing project directed toward the discovery of new natural products from endophytic fungi that were isolated from marine organisms from the Chinese sea coasts, [9][10][11][12][13][14] we have investigated the chemical constituents of an endophytic fungal strain Eurotium rubrum that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus collected from Hainan island. This paper describes the isolation, structure elucidation, and cytotoxicity of four new (1-4) and seven known (5-11) benzaldehyde derivatives. To our knowledge, compound 1, which was named as eurotirumin, possesses a new carbon skeleton with a cyclopentabenzopyran ring system. Results and DiscussionThe fungus E. rubrum was grown in potato-dextrose broth (PDB) media. The combined extracts from the culture broth and from the mycelium were fractionated by repeated column chromatography on silica gel, reversed-phase silica gel C 18 , and Sephadex LH-20, as well as by preparative TLC, to afford eleven metabolites (1-11).Compound 1 was obtained as a yellowish amorphous powder. The IR spectrum exhibited absorptions at 3442 (OH), 1729 (carbonyl), and 1632 cm Ϫ1 (double bond). The EI-MS of 1 displayed a molecular ion peak at m/z 316 [M] (Table 1). The 13 C-NMR spectrum of 1 exhibited 19 carbon signals attributable to three methyls, three methylenes, seven methines, and six quaternary carbon atoms according to the DEPT experiments (Table 2). Detailed comparison of 1D and 2D NMR spectral data of 1 with those of our recently reported data for chaetopyranin (5), a benzaldehyde derivative that was identi- Four new (1-4) and seven known (5-11) benzaldehyde derivatives were characterized from the liquid fermentation cultures of Eurotium rubrum, an endophytic fungus that was isolated from the inner tissue of stems of the mangrove plant Hibiscus tiliaceus. The structures of these compounds were determined by extensive analysis of their spectroscopic data. Among these metabolites, compound 1, which was named as eurotirumin, possesses a new carbon skeleton with a cyclopentabenzopyran ring system.

Asperamides A (1) and B (2), a sphingolipid and their corresponding glycosphingolipid possessing a hitherto unreported 9-methyl-C20-sphingosine moiety, were characterized from the culture extract of Aspergillus niger EN-13, an endophytic fungus isolated from marine brown alga Colpomenia sinuosa. The structures were elucidated by spectroscopic and chemical methods as (2S,2'R,3R,3'E,4E,8E)-N-(2'-hydroxy-3'-hexadecenoyl)-9-methyl-4,8-icosadien-1,3-diol (1) and 1-O-beta-D-glucopyranosyl-(2S,2'R,3R,3'E,4E,8E)-N-(2'-hydroxy-3'-hexadecenoyl)-9-methyl-4,8-icosadien-1,3-diol (2). In the antifungal assay, asperamide A (1) displayed moderate activity against Candida albicans.