| The malignant tumor is one of the most serious disease endangering human being' s life and health. Medication is the main treatment of tumors. Seeking and screening high effective and low poisonous anti-tumor drugs, especially from natural products, is the hotspot in medicinal research.The oceanic organisms produce a diverse array of compounds with new types of structures that are expected to be sources of novel anti-tumor drugs. Most of marine bioactive substances are so particular and unknown that they must be screened randomly, not directionally. Therefore, a sensitive, convenient and rapid screening model is required to obtain marine anti-tumor drugs successfully.In this paper, we have established a combinatoiial screening model for anti-tumor bioactive substances in the marine organisms, associating the primary Fusarium oxysporum screening with the further cytotoxicity screening. Fusurium oxysporum screening procedure only spends sixteen hours so that it can be applied in the preliminary evaluation of large numbers of samples within relative short period. As a cytotoxicity test, MTT assay is made use of in secondary investigation that has been considered as appropriate in vitro method with sensitivity, accuracy and reproductivity. The combinatorial model including the two segments has the characteristic of convenience, rapidity and economy for screening marine anti-tumor bioactive substances on a large scale.1,585 marine microorganic strains were isolated from 86 selected marine environment specimens in 16 locations of Hainan Island, including 552 bacterial strains, 683 actinomycetic strains and 350 fungal strains. 1585 fermented products from those microorganic strains were tested step by step in the combinatorial screening model. As a result, 12 microorganic metabolites showed prominent anti-tumor activity among which the bacterial strain QK I -2708' s fermented broth QK1-2708 had IDso at 3520,3078 and 4103 against CNE,SMMC-7721 and SI80 cells respectively. Additionally, the tested samples TM4-5517 and YG6-7019 exhibited significant specific inhibitory activity towards CNE cells, and NN7-5426 towards SMMC-7721 cells.Water, EtOH and EtOAc crude extracts of 12 marine animal or plant samples were investigated. EtOH and EtOAc extracts of the eleventh and the twelfth samples were all found to possess strong anti-tumor activity with IC50 under 10ug/mL against CNE, SMMC-7721 and S180 celh.Physical and chemical nature of anti-tumor substance in QK1-2708 sample was investigated. The investigation resulted that the bioactive substance has good stability in the condition of heat and acid. Its IDsoonly reduced 16.1% with the treatment in 60癈 for an hour, and 40.8% in 100癈. It kept good quality in acid, especially pH in the range from 5.0 to 7.0, but it would lose most of anti-tumor activity in high alkalinity.Anti-tumor activity and bacterial biomass of QK1-2708 cultures in different water medium were studied. The result displayed that both of them in sea water cultures is far higher than in distilled water cultures. It indicated that QK I -2708 was most likely to be an obligate marine bacterial strain.The taxonomic investigation on morphological, physiological and biochemical characters represented that QK I -2708 was a new species of Corynebacterium.The primary studies on QK I -2708 strain demonstrated that its metabolite had great potential for development as anti-tumor drugs.
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