The world oceans represent a resource of huge dimension, but their microbial diversity is still poorly understood. The chemistry of marine fungi was even a widely neglected part of natural product chemistry until recently. But symbiotic and epibiotic coexistence of fungi with higher forms of life, e.g. with sponges, forming highly specialised communities gave rise to an increasing interest in their secondary metabolism. More than 100 metabolites from marine fungi are known now, many of them showing fascinating structures or remarkable biological activities. This review gives a comprehensive summary of most structures and discusses their origin and properties.

Cultivation of the marine-derived streptomycete isolate B8005 delivered three known antibiotics, resistomycin (1), resistoflavin (3a) and tetracenomycin (4), and a further member of the rare resistomycin class, the weakly antibiotically active 1-hydroxy-1-norresistomycin (2). From a related marine strain B4842, 1 and resistoflavin methyl ether (3b) have been isolated. The formation of 2 is of interest from a biosynthetic point of view.Keywords resistomycin, 1-hydroxy-1-norresistomycin, marine streptomycetes, natural product, structure elucidationIn the course of our screening of streptomycetes for new bio-active secondary metabolites, extracts of the marine Streptomyces isolate B8005 showed inhibitory activity against Escherichia coli, Staphylococcus aureus, Streptomyces viridochromogenes (Tü 57), Mucor miehei, Candida albicans, and the microalga Chlorella vulgaris. Additionally it possessed cytotoxic activity against Artemia salina. In the TLC screening, the extract showed moderately polar yellow and red spots. Work-up delivered three known antibiotics, resistomycin (1) [1,2], resistoflavin (3a) [1,3] and tetracenomycin (4) [4], and a new resistomycin derivative, 1-hydroxy-1-norresistomycin (2), as a further active principle. From a second marine Streptomyces isolate B4842, resistoflavin methyl ether (3b) has been isolated, along with 1. Resistomycin (1) is a quinone-related antibiotic with unique structure and possesses bactericidal and vasoconstrictive activity. It inhibits RNA and protein synthesis, but has no effect on DNA synthesis [5]. It was so far the only further member of this type of compounds.The Streptomyces strain B8005 has been derived from sediment of the Laguna de Terminos at the Gulf of Mexico and was isolated on M3-medium [6]. The partial 16S rRNA gene sequence of the strain B8005 is identical with that of the strain Streptomyces albogriseolus (DSM 40003) and Streptomyces viridodiastaticus (DSM 40249). However, the strain B8005 differs from both strains in forming a chocolate brown substrate mycelium. The spore mass is gray, spore chains are spiral; the surface of spores is spiny. Melanin pigment is neither produced on peptone -yeastextract iron agar [7] nor on tyrosine agar [7] but a chocolate brown pigment is found in media like yeast -extract maltextract agar [8] and chitin agar [8]. The optimum growth temperature is at about 30°C. The strain does not grow at 10°C but shows growth at 45°C. Growth occurred in media from 0% up to 10% seawater salinity. Chitin, cellulose, starch, casein, gelatine, and esculin are degraded. The strain is catalase and nitrate reductase positive. The use of

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In a continuation of our investigation for bioactive secondary metabolites from marine microorganisms1}, we have isolated a new pluramycin type metabolite 5-indomycinone (2), along with the known antibiotic /?-indomycinone (1)2). Both compounds were extracted from the culture broth of a Streptomyces strain (B 8300), obtained from the collection of marine actinomycetes at Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany. Pluramycin metabolites containing the 4tf-anthra[l ,2-Z>]pyran-4,7, 1 2-trione nucleus to which amino sugars typically are attached at C-8 and C-10 positions, were most commonly isolated from terrestrial Streptomyces sp. The pluramycin analogues which lack any carbohydrate substitution are the pluramycinones such as indomycinones3). The pluramycins are a group of highly structurally evolved DNA reactive agents and found to have antimicrobial and OCT. 1997 anticancer activity40. We would now like to describe the taxonomy of the producing strain and the fermentation, isolation and structure determination of the new metabolite (5-indomycinone (2). Taxonomy of Strain B 8300The actinomycete strain B 8300 was isolated from sediment of the Laguna de Terminos at the Gulf of Mexico using cellulose medium5) containing 50% seawater at an incubation temperature of 18°C. The pure culture was maintained on yeast extract-malt extract agar6) (YMA). The strain forms extensive yellow aerial mycelium, with straight to flexuous (Rectiflexibiles) spore chains of about 20jum length. Spores are cylindrical about 1.1/mi long and 0.4 to 0.5/im in diameter with a smooth surface. The non fragmenting vegetative mycelium is reddish brown forming a reddish brown, diffusible pigment. The strain cannot grow at 4°C and 45°C on YMA. Poor growth occurs at 10°C and 37°C after 4 weeks. The temperature optimum is at about 30°C. Growth is obtained in the presence of 0.4 and 7% (w/v) sodium chloride but not in the presence of 10 or 13% sodium chloride on YMA. Further physiological characteristics are compiled in Table 1.The cell wall peptidoglycan of the strain contains major diagnostic amounts of L-diaminopimelic acid (l-DAP) and glycine corresponding with wall chemotype

Triterpenoid-based scaffolds betulinic acid (1a) and ursolic acid (1b), have been used for the generation of combinatorial libraries in parallel format using solid phase organic synthesis method. These templates have the potential for the synthesis and amplification of triterpenoid-based compounds with one and two-point diversity. This has been demonstrated by the synthesis of two small libraries comprising 18 derivatives each of betulinic acid and ursolic acid with structural diversity at C-3 and C-28 positions. The primary screening of antimalarial activity of these libraries against P. falciparum in vitro led to the identification of four compounds with 5 fold increase in the activity compared to betulinic and ursolic acids.