Screening Of Antitumor Metabolites From Marine Microorganisms, Strain Identification And Primary Investigation Of The Metabolites

According to the statistics from World Health Organization (WHO), malignantcancer is still the most serious disease threating human health. Excepting inhibiting thegrowth of cancer cells, most of current antitumor agents act against normal mammaliancells, consequently causing severe side effects. So it becomes an important assignmentto find a kind of anti-tumor drugs with efficiency and low side effects. Finding and re-searching high-efficiency antineoplastic agent from the nature is always a hot spot in thefield of oncotherapy. Microbes and their metabolites, because of their diversity, wereoverlooked by experts and scholars at whole world for a long time. But the traditionaldrugs from the land were limited, and another huge reservoir, marine organisms, hadbeen ignored for a long time. Many inspiring achievement had been made by scie ntiston the finding of marine compounds with anti-tumor activity. Marine organisms repre-sented an essentially unexploited reservoir for products with potentially biological andpharmacological activity. So far, many natural products derived from marine organismsin literatures were characterized by low cytotoxity and new mechanisms. In this study,two strains S-1and N16were screened from5kinds of marine microbes. A kind of a n-ticancer peptide was isolated from metabolites of Brevibacillus sp. S-1, followed by apreliminary study on its antitumor activity.Antitumor metabolites from marine microorganisms were screened by MTTmethod with BEL-7402, RKO, A549, U251and MCF-7cancer cells as models. Themarine strains were identified by16S rDNA sequence analysis and physiological bio-chemical property. The result shows that metabolites from the strains S-1and N16haveinhibitory effect on the proliferation of multiple tumor cells. Specifically, activity co m- ponent from strain S-1can inhibit MCF-7, U251and BEL-7402, IC50up to44μg mL-1,82μg mL-1and102μg mL-1, respectively; activity component from strain N16can alsoinhibit MCF-7and BEL-7402, IC50up to84μg mL-1and133μg mL-1, respectively.According to physiological biochemical property and16S rDNA sequence analysis, twostrains S-1and N16were identified as Brevibacillus sp.and Bacillus sp., respectively.Morphological observation preliminarily determines the active component can inhibitthe proliferation of BEL-7402cells. The Brevibacillus sp. S-1might be a good anti-tumor active strain for further study. This study is important for developing novel anti-cancer agents from marine microorganisms.Butanol extraction, CM Sepharose Fast Flow ion exchange Chromatography andPreparative High Performance Liquid Chromatography (PHPLC) were used to prepare akind of peptide, named SBP（Peptide from Brevibacillus sp. S-1, SBP）by MTT methord,which can inhibit the proliferation of cancer cells. The molecular weight of SBP, whichwas detected with ESI-MS, was1570Dalton. It’s worth noting that cells proliferationassay in vitro, using MTT method showed that the bioactivity peptide SBP can inhibitBEL-7402cancer cells growth potently and its IC50value was up to7.15μM, and theIC50value of Mitomycin is1.44μM. So, SBP is expected to become a kind of new an-titumor candidates agents in future development.In recent years, the incidence of hepatoma is increasing and the mortality of hepa-toma is also the highest among the world. So using BEL-7402cells as model in the ac-tive research of antitumor peptide has practical significance. The morphological changeof BEL-7402cells induced by SBP was observed by phase contrast microscope. Theresult shows that morphological observation preliminarily determines the SBP can in-hibit the proliferation of BEL-7402cells.