Secondary Metabolites From Two Fungal Strains Associated With Mangrove Lumnitzera Littorea And Their Bioactivities

Secondary metabolites from mangrove-derived fungi have been regarded as an important source of the lead compounds in drug discovery.Mangrove Lumnitzera littorea was an endangered medicinal plant species of the genus Lumnitzera,which was hitherto found to distribute in the Hainan island of China.To the best of our knowledge,there is a rare report for the chemical and bioactive investigations of secondary metabolites from fungi associated with L.littorea.The chemical investigations of the secondary metabolites from two fungal strains associated with L.littorea were performed.The compounds were isolated by a combination of column chromatography(CC)for silica gel,sephadex LH-20,RP-18and semi-preparative HPLC.Further the structures of these compounds were elucidated by spectroscopic analysis composed of 1D and 2D-NMR,MS,IR,UV,and by comparision with literatures,as well as by quantum chemical calculations.Totally 17 compounds were affored from Nigrospora sp.S30,with structual varieties of nine diketopperazines(1-9),two cyclopentenones(10-11)and seven aromatic hydrocarbons(12-17).Among them,compounds 1-2 were new compounds and compounds 1-17 were isolated from the species for the first time.In addition,a total of 23 compounds were obtained from Aspergillus sp.LLN2,including two isochroman(18-19),seven polyketones(20-26),two isocoumarins(27-28),eight aromatic hydrocarbons(29-36)and other categories of four compounds(37-40).Among them,compounds 18-20 were new compounds and compounds 18-21,23,25,29,33-35 and 37-40 were isolated from this species for the first time.The purified compounds above were evaluated for anti-ischemic stroke,antioxidant and antimicrobial activities.And the results indicated that compounds 19and 22 showed good anti-ischemic stroke activity,and the survival rates of damaged cells were 57.05%and 54.53%at 100?M,which were similar to the positive control Edaravone(57.27%).The survival rate of injured cells was 48.21%when the concentration of compound 37 was 50?M.Compounds 29,30,and 32 showed evident antioxidant activities with IC₅₀values of 1.57,1.80 and 1.91 m M,respectively,in contrast with positive control trolox with an IC₅₀value of 1.50 m M.Compound 38showed weak antibacterial activity against E.coli,B.cereus,S.aureus and B.subtilis with the same MIC value of 25?g/m L.