Secondary Metabolites From Two Chaetomium And Their Antimicrobial Activity

The ascomycetes fungi of the genus Chaetomium(more than 400 species)are widely distributed in soil,air,plants and animals.Chaetomium fungi produce various types of secondary metabolites,such as polyketones,steroids,indoles,diketopiperazines,terpenes,chromogenic ketones and anthraquinones.These metabolites exhibit a wide range of biological activities,such as antibacterial,immunomodulatory,cytotoxic activity,and antitumor activity.In order to systematically investigate the secondary metabolites of the genus Chaetomium,C.virescens CIB 608 and C.nigricolor were chemically studied,using.chromatographic techniques to isolate the compounds,and using spectroscopic techniques to characterize the them.From the fermentation broths of the two fungi,31 compounds were separated and identified.Among them,compound 1 was a new natural product,compound 2was a new compound.It was fund that chaetocin possesses antimicrobial activity against Staphylococcus aureus.Major results are as follows.1.A total of 22 compounds(1-22)were separated from the ethyl acetate extract of solidstate fermented rice culture of C.virescens.They were identified as 7-methoxy-eugenitol(1),chaetocin D(2),eugenitol(3),2,4-dihydroxy-3,6-dimethyl-benzoic acid(4),O-methoxysterigmatocystin(5),sterigmatocystin(6),dihydrosterigmatocystin(7),averufin(8),nidurufin(9),adenosine(10),2'-O-methoxyadenosine(11),p-hydroxybenzoic acid(12),thymidine(13),p-hydroxybenzaldehyde(14),p-hydroxybenzoic acid(15),(S)-3-hydroxy-3-phenylpropionic acid(16),chaetocin(17),chaetocin B(18)and chaetocin C(19),ergosterol(20),(22E,24R)-ergosta-7,22-diene-3?,5?,6?-triol(21),(20S,22 E,24R)-5?,8?-bridged dioxy-ergosta-6,22-diene-3-?-triol(22).Compound 2 was a new compound.Compound 1was a new natural product.Its structure was confirmed by using 1D and 2D NMR techniques for the first time.Compounds 18 and 19 with –S3-bridges are unstable.During the separation and purification process,they converted into compound 17.By lowering the concentrating temperature and avoiding light,compounds 18 and 19 were isolated as pure ones for the first time and their structures were confirmed by 1D and 2D NMR techniques.Agar disc diffusion assay indicated that compound 17 possessed anntimicrobile activity against Staphylococcus aureus at the concentration of 1.0 ?g/m L.2.A total of 9 compounds(23-31)were obtained from the ethyl acetate extract of the solid-state fermentated rice culture of C.nigricolor.They were identified as(22E,24R)-ergosta-7,22-diene-3?,5?-diol-6-one(23),(22E,24R)-ergosta-7,22-diene-3?,5?,9?-triol-6-one(24),(22E,24R)-ergosta-7,22-diene-3?,5?,6?,9?-tetraol(25),(22E,24R)-ergosta-7,22-diene-3?,5?,6?-triol(26),3-indolecarboxaldehyde(27),3-indolecarboxylic acid(28),1-hydroxy-3-(1H-indol-3-yl)propan-2-one(29),1-(3-indolyl)-2,3-dihydroxy-propan-1-one(30)and(2S)-3,3-bis(1H-indol-3-yl)propane-1,2-diol(31).