Secondary Metabolites of a Deep Sea Derived Fungus Aspergillus versicolor CXCTD-06-6a and Their Bioactivity

In order to obtain novel secondary metabolites, a deep sea inhabiting fungus Aspergillus versicolor CXCTD-06-6a was investigated. One new diketopiperazine brevianamide W(1a), as well as five known diketopiperazine alkaloids, diketopiperazine V(1b), brevianamide Q(2), brevianamide R(3), brevianamide K(4), and brevianamide E(5), were isolated from the Et OAc extract of the fermentation broth. Their structures were elucidated by spectroscopy techniques(NMR, MS). The six compounds exhibited moderate radical scavenging activity against DPPH with clearance ratio of 55.0%(1a and 1b), 53.7%(2), 46.2%(3), 61.4%(4) and 19.3%(5) at a concentration of 13.9 μmol L-1, respectively; while the positive control ascorbic acid showed a ratio of 70.3% at the concentration of 28.4 μmol L-1.

The Cytotoxic Constituents from Marine-derived Streptomyces 3320^(#)

The present work studies the chemical constituents from marine-derived streptomyces 3320^# and their antitumor activities. The n-BuOH extract of the ferment broth of 3320^# was chromatographed on silica gel, Sephadex LH-20, ODS columns and HPLC to separate the compounds with antitoumor activities. Their structures were identified using IR, UV, NMR, MS spectroscopic techniques and compared with published data. The antitumor activities of the isolates were assayed using SRB method and flow cytometry assay, accompanied with the morphological observation of the cells under light micro- scope against mammalian tsFT210 cells. Ten compounds, cyclo-（Ala-Leu） 1, cyclo-（Ala-Ile） 2, cyclo-（Ala-Val） 3, cyclo- （Phe-Pro） 4, cyclo-（Phe-Gly）5, cyclo-（Leu-Pro）6, 1-methyl-1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid 7, N-（4- hydroxyphenethyl） acetamide 8, 4-methyoxy-l-（2-hydroxy） ethylbenzene 9 and uridine 10, were isolated from the ferment broth of streptomyces 3320^# . Among them, compounds 6, 7, 8 and 10 showed potent cytotoxicity against the tsFT210 cell with the IC50 values of 3.6, 7.2, 5.2 and 1.6 mmol L-1, respectively. Compounds 8, 10 also exhibited apoptosis inducing activity under 2.0 mmol L-1. Compounds 6, 7, 8 and 10 are the principle bioactive constituents responsible for the antitumor activities of marine streptomyces 3320^#. Compound 7 was isolated from this species for the first time.

Construction of a Metagenomic DNA Library of Sponge Symbionts and Screening of Antibacterial Metabolites

To study the bioactive metabolites produced by sponge-derived uncultured symbionts, a metagenomic DNA library of the symbionts of sponge Gelliodes gracilis was constructed. The average size of DNA inserts in the library was 20 kb. This library was screened for antibiotic activity using paper disc assaying. Two clones displayed the antibacterial activity against Micrococcus tetragenus. The metabolites of these two clones were analyzed through HPLC. The result showed that their metabolites were quite different from those of the host E. coli DNA and the host containing vector pHZ132. This study may present a new approach to exploring bioactive metabolites of sponge symbionts.

A Polysaccharide-Degrading Marine Bacterium Flammeovirga sp.MY04 and Its Extracellular Agarase System

Bacteria of the genus Flammeovirga can digest complex polysaccharides (CPs), but no details have been reported regarding the CP depolymerases of these bacteria. MY04, an agarolytic marine bacterium isolated from coastal sediments, has been identified as a new member of the genus Flammeovirga. The MY04 strain is able to utilize multiple CPs as a sole carbon source and grows well on agarose, mannan, or xylan. This strain produces high concentrations of extracellular proteins (490 mg L-1 ± 18.2 mg L-1 liquid culture) that exhibit efficient and extensive degradation activities on various polysaccharides, especially agarose. These proteins have an activity of 310 U mg-1 ± 9.6 U mg-1 proteins. The extracellular agarase system (EAS) in the crude extracellular enzymes contains at least four agarose depolymerases, which are with molecular masses of approximately 30-70 kDa. The EAS is stable at a wide range of pH values (6.0-11.0), temperatures (0-50℃), and sodium chloride (NaCl) concentrations (0- 0.9 mol L-1). Two major degradation products generated from agarose by the EAS are identified to be neoagarotetraose and neoagarohexaose, suggesting that β-agarases are the major constituents of the MY04 EAS. These results suggest that the Flammeovirga strain MY04 and its polysac-charide-degradation system hold great promise in industrial applications.

Structures and Antiviral Activities of Butyrolactone Derivatives Isolated from Aspergillus terreus MXH-23

A new butyrolactone derivative,namely butyrolactone Ⅷ （1）,and six known butyrolactones （2-7） were separated from the ethyl acetate （EtOAc） extract of the fermentation broth of a fungus,Aspergillus terreus MXH-23.The chemical structures of these metabolites were identified by analyzing their nuclear magnetic resonance （NMR） and mass spectrometry （MS）.Known butyrolactone derivatives contain an α,β-unsaturated γ-lactone ring with α-hydroxyl and y-benzyl,and butyrolactone Ⅷ （1） was the first butyrolactones contains α-benzyl and γ-hydroxyl on α,β-unsaturated lactone ring.All of the butyrolactone derivatives were tested for their anti-influenza （H 1N 1） effects.Derivatives 4 and 7 showed moderate antiviral activities while the newly-identified,derivative 1,did not.

Strain and Culture Medium Optimization for Production Enhancement of Prodiginines from Marine-Derived Streptomyces sp. GQQ-10

A mutant (GQQ-M6) of a Sponge-Derived streptomyces sp. GQQ-10 obtained by UV-induced mutation was used for producing prodiginines (PGs). Single factor experiments and orthogonal array design (OAD) methods were employed for medium optimization. In the single factor method, the effects of soluble starch, glucose, soybean flour, yeast extract and sodium acetate on PGs production were investigated individually. In the subsequent OAD experiments, the concentrations of these 5 key nutritional components combined with salinity were further adjusted. The mutant strain GQQ-M6 gave a 2.2-fold higher PGs production than that of the parent strain; OAD experiments offered a PGs yield of 61mg L-1, which was 10 times higher than that of the initial GQQ-10 strain under the original cultivation mode.