Studies On The Antitumor Bioactive Constituents Of Secondary Metabolites Of Two Algicolous Fungi

Algicolous fungi are the fungi that live with algae (primarily red, green and brown alage). Algicolous fungi play an important role in the chemical defence of the host against microbes and other algae. This study has undertaken a piece of research on the metabolites of algicolous fungi, studies include applying a piece of special methods without the interference of antibiotics for algicolous fungi, screening of antitumor-active fungi, selecting aimed strains, fermentation studies, bioassay-guided fractionation, structural elucidation, preliminary evaluation for anti-tumor activities of pure compounds.Twenty eight algae samples were collected from different intertidal zones of Yellow Sea. From these algae, two hundreds twenty one strains of algicolous fungi were selectively isolated. By using lethiferous effect on brine shrimp and chronic medulla leucocythemia cell (K562) to screening their antitumor activity, eight strains showed brine shrimp activities and eight showed cytotoxic activities. The active ratio was 7.2%.According to antitumor-bioactivity evaluation and chemical analysis, we selected algicolous fungus m-3-4 and i-1-1, and studied their cultivated conditions. Then two active strains were fermented, respectively. The whole broth was extracted with ethyl acetate to give active EtOAc extract.Fifteen compounds were isolated from the bioactive part, EtOAc extract of the two strains m-3-4 and i-1-1 by repeated column chromatography on silica gel, Sephadex LH-20 and RP-18, followed by reverse-phase high performance liquid chromatragraphy. The structures were elucidated mainly by use of spectroscopic method (UV, IR, MS, 1D NMR, 2D NMR) and according to their ph ysicochemical properties. Eleven compounds had been confirmed: new citrinin derivative (1), cyclopenol(2), cladosporin(3), ergosterol(4), citrinin(5), emodin(6), gliotoxin(7), cyclo-L-tryptophyl-L-proline(8),demethoxyfumitremorginC(9),(2R,3S)-2,3,4-trimethyl-2,3-dihydrobenzofuran-5,7-diol(10),dimethyl2,2'-(4,4'-oxybis(4,1-phenylene))diacetate(11). Compound 1 is a new compound. Compound 7 had strong antitumoractivity. The structuress of other compounds were being elucidated.This study supply important resource strains for the study of antitumor-active components of algicolous fungi.