Study On Isolation,Indentification And Their Secondary Metabolites Of Two Endophytic Fungus From Halophytic Salicornia Bigelovii Torr

Microbial secondary metabolites are always one of the attractive topics in the area of natural product,and a large number of compounds with vauluable application derived from microorganisms.With the advancement of investigation,however,probabilities of discovering new compounds are decreasing.It is urgently to require new techniques and methods to find new natural products.Recently,with the development of the molecular biology,the strageies for screening the polyketide synthase genes(PKSs)have successfully revealed the important pipelines for the discovery of new microbial metabolites.24 endophytic fungi were isolated and purified from Salicornia bigelovii Torr.by the PDA plate and the slant culture.Based on a type ? polyketide synthase(PKS I)genes screening approach,four strains containing PKS genes were obtained,encoded as Salicorn 9,Salicorn 13,Salicorn 19 and Salicorn 46 respectively.These four strains were identified as Alternaria alternate,Chaetomium globosum,Fusarium tricinctum and Penicillium citrinum by morphological study and molecular analysis respectively.The strain Salicorn 19 and 46 had been fermented scalely,and Salicorn 46 was selected for further cultivation by the addition of Cu2+ to attempt finding new metabolites.The fermentation product was extracted and separated by silica gel column chromatography and Sephadex LH-20.4 pure compounds were isolated from Salicorn 19 and indentified as cerebroside C(1),fusartricin(2),fusarielin B(3)and enniatin B(4)including a new compound fusartricin(2)by using modern spectroscopic techniques such as infrared(IR),mass spectrometry(MS),circular dichroism(CD),ultraviolet spectra(UV)and nuclear magnetic resonance(1H,13C,1H-1H COSY,HSQC and HMBC NMR).7 pure compounds were isolated from Salicorn 46 and determined to be alternaroside B(5),(3?,5a,8a,22E)-5,8-epidioxyergosta-6,22-dien-3-ol(6),citrinin(7),pencitrin 1(8),pencitrin 2(9),penicitrinone A(10)and penicitrinone E(11)consist of two new compounds pencitrin 1(8)and pencitrin 2(9).The final absolute configurations(AC)of compounds(9-11)were determined using IDDFT-calculated electronic circular dichroism(ECD)spectra.The antioxidant activities of the compounds above were assayed by DPPH radical scavenging method,results showed that penicitrinone E(11)had antioxidant activity with the value of IC50 94.66 ?M.MTT method was used to evaluate the anti-tumor activities of penicitrinone E(11)and results exhibited apparent antiproliferative activities towards A549 and HepG-2 cells with EC50 values of 40.47,53.57 ?M,respectively.