Screening Of Cytotoxic Marine Fungi And Studies On The Active Alkaloids From Two Selected Marine Fungal Strains

Marine microorganism is a rich source of secondary metabolites content with diverse structures and various biological activities. A study is carried out to investigate the bioactive lead compounds derived from marine microorganisms. By combinatory use of brine shrimp bioassay testing, cytometric bioassay against tsFT210 cell line and K562 cell line and antibiotic experiment, and chemical analysis, 17 bioactive strains have been screened from 287 strains isolated from nine marine samples. Two fungal strains Aspergillus sydowi PFW1-13 and Aspergillus sp. HSN-2 are selected for further chemical investigation.Monitoring by bioassay-guided isolation, the active fraction is chromatographed on silica gel, Sephadex LH-20 and prepared TLC, and preparative reversed phase HPLC, respectively, thirty five compounds are isolated from the marine-derived fungal strain Aspergillus sydowi PFW1-13. By means of spectroscopic methods (1D-NMR, 2D-NMR, MS, IR, UV, etc.), their structures are elucidated as 14-norpseurotin A (1), pseurotin A (4), 18-carbonyl tryprostatin A (5), methoxyl-spirotryprostatin B (6), 13-methoxyl verruculogen TR-2 (7), 12-hydroxyl terezines D (8), spirotryprostatin A (9), terezines D (10), fumitremorgin C (12), cyclotryprostatins B (13), verruculogen (16), tryptoquivaline O (18), fumiquinazolines F (19), fumiquinazoline G (20), fumiquinazoline J (21), fumiquinazoline A (22), fumiquinazoline C (23), fumiquinazoline D (24), bisdethiobis(methyl)gliotoxin (26), didehydrobisdethiobis- (methylthio)gliotoxin (27), fumigaclavine (29), fumigaclavine A (30), Pyripyropene A (31), Pyripyropene E (32), hydrohelvolic acid (33), helvolic acid (34), Ergosterol (35), isosclerone (36), emodin(37), questin (38), Monomethylsulochrin (39), 5-methyl- benzene-1,3-diol (40), 1,7-dihydroxyl-3-methyl-8-ketomethoxyxanthone (41), benzoic Acid (42), scytalone (43). By the same procedure, eight compounds are isolated from the fungal strain Aspergillus sp. HSN-2. The structures are elucidated as furanylspiro-lactam (2) and (3), typrostatins B(11), 12, 13-dihydroxyfumitremorgin C (14), fumitremorgin B (15), cyclo-L-tryptophyl-L-proline (17), gliotoxin (25), 2,5- Piperazinedione (28). Among them, compounds 1, 5-8 and 33 are new compounds.The anti-tumor activities of these compounds are evaluated in vitro by SRB and flowed cytometry using mouse cdc2 mutant cells tsFT210, mouse leukemia cells P388, human leukemia carcinoma cells K562 and human cancer cells A549, BEL-7402 and HL60. Thirty compounds show potential anti-tumor activities. New compounds 1, 5, 6 and 33 exhibit moderate inhibiting the proliferation of many cancer cells, such as mouse leukemia cells P388, human cancer cells A549, BEL-7402 and HL60. New compounds 7, 8 and 33 inhibit the proliferation of mouse leukemia cells P388, human cancer cells A549, BEL-7402 and HL60. Compound 41 has apoptosis activity. Compound 32 exhibit moderate inhibiting the proliferation of K562 and P388 cell lines. Compounds 2, 16, 18-24, 29, 36 and 38 inhibit the proliferation of tsFT210 cells. Compounds 10-13, 15, 26, 27, 29 and 31 show weak inhibiting the proliferation of tsFT210 cells. Compound 35 exhibits apoptosis inducing and cytotoxic activities. In addition, compounds 1, 4, 33 and 34 are found to be active against Escherichia coli, Bacillus subtilis and Micrococcus lysoleikticus.In a word, there are forty three compounds which are obtained from the two fungal strains, five compounds in thirty two alkaloid compounds are new compounds. Studies mentioned above provide novel structures for searching leading antitumor compounds and it proves the method we use is effective in finding new active alkaloid compounds.