Secondary metabolites from marine microorganisms: bacteria, protozoa, algae and fungi. Achievements and prospects

A new macrocyclic trichothecene, 12,13-deoxyroridin E, produced by the marine-derived fungus Myrothecium roridum collected in Palau

A new macrocyclic trichothecene, 12,13-deoxyroridin E (1), and three known compounds, roridin E (2), verrucarin A (3), and verrucarin J (4), were obtained as cytotoxic components from the marine-derived fungus Myrothecium roridum, isolated in Palau. 12,13-Deoxyroridin E is the second example of a macrocyclic trichothecene possessing a double bond at C-12-C-13 and was about 80-fold less cytotoxic than roridin E, the epoxide variant.

Lorneamides A and B: two new aromatic amides from a southern Australian marine actinomycete

A marine actinomycete (MST-MA190) isolated from a sample of beach sand collected near Lorne on the southwest coast of Victoria, Australia, has yielded two new aromatic amides, lorneamide A (1) and lorneamide B (2). The lorneamides belong to a novel class of tri-alkyl-substituted benzenes, and their structures were determined by spectroscopic methods.

Ascosalipyrrolidinone A, an antimicrobial alkaloid, from the obligate marine fungus Ascochyta salicorniae

From the green alga Ulva sp., the endophytic and obligate marine fungus Ascochyta salicorniae was isolated. A. salicorniae was mass cultivated and found to produce the unprecedented and structurally unusual tetramic acid containing metabolites ascosalipyrrolidinones A (1) and B (2). Additionally, the new natural product ascosalipyrone (3) and the known metabolites 4 and 5 were obtained. Ascosalipyrrolidinone A (1) has antiplasmodial activity toward Plasmodium falciparum strains K1 and NF 54, as well as showing antimicrobial activity and inhibiting tyrosine kinase p56lck.

Mangicols: structures and biosynthesis of A new class of sesterterpene polyols from a marine fungus of the genus Fusarium

A marine fungal isolate, tentatively identified as Fusarium heterosporum, has been found to produce a series of structurally novel sesterterpene polyols, the mangicols A-G (4-10). The structures of the new compounds, including the stereochemistry of mangicol A, were assigned by interpretation of spectral data derived from both natural products and synthetic derivatives. The mangicols, which possess unprecedented spirotricyclic skeletal components, show only weak to modest cytotoxicities toward a variety of cancer cell lines in in vitro testing. Mangicols A and B, however, showed significant antiinflammatory activity in the PMA (phorbol myristate acetate)-induced mouse ear edema model. A biosynthetic pathway for the neomangicol and mangicol carbon skeletons is proposed on the basis of the incorporation of appropriate radiolabeled precursors.

Novel polyketide metabolites from a species of marine fungi

Fermentation of a marine fungal species obtained from a tissue sample of a marine sponge collected in Indonesia in October 1996, yielded the novel hexaketide compounds iso-cladospolide B (1); seco-patulolide C (2); the 12-membered macrolides, pandangolide 1 (3) and pandangolide 2 (4); and the known terrestrial fungal metabolite, cladospolide B (5).

Three new metabolites from marine-derived fungi of the genera coniothyrium and microsphaeropsis

The marine sponges Ectyplasia perox and Myxilla incrustans were investigated for associated fungal strains. Among others, a Coniothyrium sp., from E. perox, and a Microsphaeropsis sp., from M. incrustans, were isolated, cultured, and investigated for their biologically active secondary metabolite contents. The new compound microsphaeropsisin (1) together with the known compounds (R)-mellein (4), (3R,4S)-hydroxymellein (5), (3R,4R)-hydroxymellein (6), and 4, 8-dihydroxy-3,4-dihydro-2H-naphthalen-1-one (7) were isolated from the Microsphaeropsis sp. From culture extracts of the Coniothyrium sp., the new compounds (3S)-(3',5'-dihydroxyphenyl)butan-2-one (2) and 2-(1'(E)-propenyl)-octa-4(E),6(Z)-diene-1,2-diol (3), together with the six known metabolites (3R)-6-methoxymellein (8), (3R)-6-methoxy-7-chloromellein (9), cryptosporiopsinol (10), phenylethanol, (p-hydroxyphenyl)ethanol, and 2-(hydroxymethyl)furan, were obtained. All structures were determined using spectroscopic methods. With the exception of 3, all compounds were tested for their antimicrobial properties, and all but 10 demonstrated significant antimicrobial activity in agar diffusion assays.