Studies On Bioactive Constituents Of The Gorgonian Muriceides Collaris

A gorgonian,also known as sea whip or sea fan,is a sessile animal of the Subclass Alcyonaria,Class Anthozoa,Phylum Coelenterata found throughout the oceans of the world,especially in the tropics and subtropics from inter-tidal to as deep as 4,000 meters.There are 45 species from seven families of gorgonians in China, mainly located in Hainan,Guangdong,Zhejiang and Taiwan coast.Studies in the past half century showed that a variety of novel and bioactive chemical constituents were gained from the gorgonian.The gorgonian Muriceides collaris were collected from the coast of Weizhou Island,Guangxi province,China in April,2006.To the best of our knowledge,this is the first report of the chemical constituents and biological activities from the genus Muriceides.In our ongoing program to search for natural products with unique structural features and pronounced biological activities,this paper systematically investigated on the chemical constituents and biological activities of the gorgonian Muriceides collaris.Isolation and structure determination:Monitoring by bioassay-guided isolation,the MeOH extract of the gorgonian Muriceides collaris was chromatographed on silica gel,TLC and Sephadex LH-20,and semi-preparative HPLC,respectively,then thirty-two compounds were isolated and purified from the gorgonian Muriceides collaris.Twenty-seven compounds were identified on the basis of spectral methods(1D-NMR,2D-NMR,MS,IR,etc.) and their physicochemical properties.Among them,there were seven new compounds(1-7) and four new natural products(8-11).These compounds were structurally elucidated as fourteen guaiane sesquiterpenoids,namely,2-tropolonylguaiazulene(1),collarisin A(2), collarisin B(3),collarisin C(4),2-formyl-8,9-dihydro-linderazulene(5), 2-formyllinderazulene(6),guaiazulene-2,9-dione(9),2-formylguaiazulene(10), 2-methoxylguaiazulene(11),guaiazulene(12),4-forrnyl-7-isopropyl-10-methyl -az ulene(13),sesquiterpene ketolactone(14),guaianediol(15),guaia-l(5),6-diene (16);and two indene sesquiterpenoids,namely,6-formyl-5-isopropyl-3 -hydroxymethyl-7-methyl-1H-indene(7),5-isopropyl-3,7-dimethyl-1H-indene-1-one (8);and one cholesterol(17);and one batyl alcohol(18);and three benzoyl derivatives,namely,benzoic acid(19),diisobutyl phthalate(20),1, 2-benzenedicarboxylic acid bis(2-ethylhexyl) ester(21);and two miazines,namely, uracil(22),thymine(23);and four nucleosides,namely,2'-deoxyuridine(24), 2'-deoxythymidine(25),thymidine(26),2'-deoxyadenosine(27).Biological activities:Sixteen sesquiterpenoids(1-16) were evaluated for their cytotoxicities against P388 and BEL-7402 cancer cell lines by the MTT method.The results indicated that compounds 9-10,12 showed cytotoxicities in certain extent. Among them,compound 9 had moderate cytotoxicities against P388 with the inhibition rate 57.46%at concentration of 50 ug/mL and weak cytotoxicities against BEL-7402 with the inhibition rate 15.42%at the same concentration.Compound 10 exhibited strong cytotoxicities against P388 and BEL-7402 with the inhibition rate 95.67%and 82.52%at concentration of 50μg/mL.Compound 12 showed weak cytotoxicities against P388 and BEL-7402 with the inhibition rate 21.94%and 9.45% at concentration of 50μg/mL.In addition,compound 9 exhibited potent antibacterial activity against vibrio anguillarum,vibrio harveyi and vibrio alginolgticus; compounds 10,16 had significant antibacterial activity against vibrio anguillarum.Moreover,possible biosynthetic pathways of sesquiterpenoids were postulated according to their structures and literatures in the paper.Based on the results of this research,we could do further more.