| Microorganisms in extraordinary environments have special biogenetic pathway and have become an important source of bioactive secondary metabolites. A study was carried out to investigate the potential anti-tumor compounds derived from microorganisms in extraordinary environments. This dissertation describes the discovery of several new antitumor lead compounds produced by 6 strains of halotolerant fungi from mangrove ecosystems and salt marsh and 1 strain of microalga. Studies include screening of microbial talented strains to produce secondary metabolites with large yield and novel structure, fermentation studies, fractionation, structural elucidation and preliminary evaluation for anti-tumor activities of pure compounds.Chemical diversity of 43 strains of mangrove fungi and 20 strains of salt marsh fungi with cytotoxic and antimicrobial activities were detected by TLC and HPLC methods. 6 strains including 3 talented strains were chosen as the working strains because of their large variety of metabolites. And one active strain was chosen from 48 strains of marine microalgae by brine shrimp lethality assay and cytotoxicity assay on tsFT210 cell lines.Optimization of fermentation condition for talented strains was studied, and large-scale fermentation and preparation of the active fractions were performed to obtain the active fractions of the talented strains. Compounds were isolated and purified by means of solvent extraction, silica gel column chromatography, Sephadex LH20 column chromatography, and PHPLC. From fungus Aspergillus ustus 094102, 42 compounds (1-42) were isolated; from fungus Penicillium expansum 091006, 16 compounds (43-58) were isolated; from Aspergillus flavus 092008, 8 compounds (59-66) were isolated; from Penicillium citrinum B-57, 15 compounds (67-81) were isolated; from Penicillium sp. B-58, 16 compounds (82-97) were isolated; from Spicaria elegans KLA03, 7 compounds (98-104) were isolated; from Ruttnera spectabilis H55, 2 compounds (105-106) were isolated. Their structures were elucidated by physicochemical properties and spectral analysis (IR, UV, MS, NMR, CD, etc.). Among them, 42 new compounds were identified and structures belonged to drimane-type sesquiterpenoids (1-11), isochroman derivatives (14-21), ophiobolin-type sesterterpenoids (24-29), phenolic compounds (34-39), tricresol trimers (43-48), bisabolane-type sesquiterpenes (49-50), aflatoxin (59), citrinin drimers (67-68), and biphenyl compound (98). In addition, the types of the known compounds are involved in dipeptides (41, 54-55, 64, 82-87), pyran-2-one derivatives (65, 88-91), anthraquinones (63, 79-81), citrinin and derivatives (73-78), sterols (40, 57-58), triterpene (56), tetiamic acid (72), aspochalasin (101), carotenoid (105) and fatty acids (106).The cytotoxicity against two cancer cell lines, A549 and HL60, were assayed by MTT, SRB and flow cytometry methods. As the results, new compounds 18, 27, 28 and 44 showed significant cytotoxicity with IC50 values of 0.13μM (HL-60), 0.6 and 0.8μM, 2.4 and 1.7μM, 1.9 and 5.4μM respectively; new compounds 5, 7, 9, 24, 29, 43, 45, 47 showed moderate cytotoxicity with IC50 values of 30.0 and 20.6μM, 10.5μM (A549), 9.0μM (HL-60), 15.1 and 7.0μM, 33.8 and 7.2μM (HL-60), 15.7μM (HL-60), 18.2μM (HL-60), 20.8μM (HL-60) respectively. |
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