Secondary Metabolites And Their Antibacterial Activity Of Anthogorgia Caerulea And Its Associated Bacterium

In search for antibacterial bioactive secondary metabolites from marine organisms as the material base for food natural preservative, the chemical constituents of gorgonian Anthogorgia caerulea collected from the coast of Weizhou Island, Guangxi province and its associated bacterium Halobacillus sp. were systematically investigated, and the antibacterial activity of some compounds isolated from the two marine organisms were also evaluated.The gorgonian Anthogorgia caerulea belongs to Order Gorgonacea, Family Acanthogorgiidae.21compounds were isolated and purified from the ethyl acetate and n-butanol extracts of A. caerulea by the methods of various classical column chromatographies (CC, VLC, TLC, Sephadex LH-20,) and Semi-preparative HPLC. On the basis of modern spectroscopic analysis(NMR, IR,MS) and the physicochemical properties, as well as comparison with literatures, the structures of14of the21compounds were identified as dibutyl phthalate(A1), di-(2-ethylhexyl) phthalate (A2),4-methoxy-5-methyl-pyrimidine(A3),1-methyl hypoxanthine(A4),1,8-di-methyl hypoxanthine(A5), 1,2,9-trimethyl hypoxanthine(A6), uracil(A7), thymine (A8), theophylline (A9),caffeine(A10),thymidine(All),1,3-dimethyl-xanthosine(A12),ergost-22-ene-4,23-dimethyl-1,3,9,11-tetrol(A13), docosane (A14). All the compounds were firstly obtained from this animal.The gorgonian-associated bacteria were also studied.90bacterial strains were isolated from A.caerulea. Among them,6bacterial strains had significant activities against four species of food spoilage bacteria(Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Bacillus cereus). All the6bacterial strains were identified by16S rRNA gene sequences analysis. The result showed that5of the6bacterial strains belonging to genera Bacillus, the other belonging to genera Halobacillus.One active bacterial strain (Halobacillus sp.) was selected for further study of its secondary metabolites. After the large-scale fermentation,29compounds were isolated from the ethyl acetate extract of the culture broth of Halobacillus sp. On the basis of modern spectroscopic analysis,27of the29compounds were identified as cyclo-(2-hydroxy-Pro-Leu)(H1), cyclo-(4-hydroxy-Pro-a-amino-benzeneacetic acid)(H2), cyclo-(Gly-Abu)(H3), cyclo-(Gly-Leu)(H4), cyclo-(Gly-L-Pro)(H5), cyclo-(D-Pro-L-Val)(H6), cyclo-(Pro-Leu)(H7), cyclo-(4-hydroxy-Pro-Leu)(H8), cyclo-(N-methyl-Gly-Phe)(H9), cyclo-(4-hydroxy-Pro-Phe)(H10), cyclo-(4-hydroxy-Pro-N-methyl-Phe)(H11),cyclo-(L-2-hydroxy-Pro-Phe)(H12), cyclo-(pipecolinyl-phenylalanine)(H13), cyclo-(Trp-3-methyl-Pro)(H14),5-methyl-2,4- imidazolidine dione (H15),5,5-dimethyl-2,4-imidazolidinedione (H16), uracil(H17),thymine(H18),3-hydroxy-2-piperidone(H19),2-phenylacetamide (H20),4-phenyl-3-butenamide(H21),1,3-benzenediacetamid(H22),N-methyl-1,2-benzenediamine (H23),4-hydroxy phenethylethanol(H24),2-methyl phenyl acetate(H25), phenylacetic acid-2-(4-hydroxyphenyl) ethyl ester (H26),1-docosanamine(H27). Among them, there were2new compounds (H1、H2) and3new natural products (H11,H14,H21). All the compounds except H10were firstly obtained from this bacterium.Sixteen pure compounds (A1、A2、H1-H14) were evaluated for their antibacterial activity. Compound H2、H7and H10showed optimum activities against four species of food spoilage bacteria.In addition, the research development of chemical constituents and their bioactivities of chinese gorgonians from2001to2011was summaried in the first chapter of this paper, and only new compounds were reported.