Studies On The Secondary Metabolites Of Three Mangrove Endophytic Fungi From South China Sea

Marine natural products is a hot spot in recent research and Marine microorganisms have become an important source of pharmacologically active metabolite.Mangrove endophytic fungi was one of the important member of Marine microorganisms and live in a ecosystem that transition from land to sea.It could produced many unique,novel and bioactive secondary metabolites,so it has an expansive foreground to study.To study the bioactive secondary metabolites from three bioactive mangrove endophytic fungi,the isolation and purification of the compounds were performed via various chromatographic techniques,and their structures were determined through spectroscopic analysis of NMR,ESI-MS,X-Ray combined with their physicochemical data.In this research,21 compounds among which eight are novel ones were isolated and identified.The antimicrobial and cytotoxic activities of the isolates were evaluated by paper disco diffusion method and MTT method,respectively.And the inhibitory activity of acetylcholinesterase was also evaluated by Ellman colorimetric method.Seven compounds were isolated from the fermentation broth of Bionectria ochroleuca HHS111023 and identified as 2-hydroxy-3-phenylpropyl3,5-dihydroxyoctanoate?1?,Lasiodiplodin?2?,?R?-de-O-methyllasiodiplodin?3?,?5S?-5-hydroxylasiodiplodin?4?,?5R?-5-hydroxylasiodiplodin?5?,methyl?E?-11,12,15-trihydroxyoctadec-13-enoate?6?,4-hydroxyphenethyl alcohol?7?,p-hydroxyphenylacetic acid methyl ester?8?and 4-hydroxybenzaldehyde?9?.Compound 1 was a new compound.Compound 2 showed inhibitory effect against Candida albicans and compound 3 showed inhibitory effect against Ralstonia solanacearum.Compound 2 exhibited cytotoxic activities in vitro against SGC-7901.and compound 3 exhibited cytotoxic activities in vitro against K-562 tumor cell lines with IC₅₀ values of 42.5,52.0 mM,respectively.Five compounds were isolated from the fermentation broth of Schizophyllum sp.BG-12 and identified as Schizophyllum A?10?,Schizophyllum B?11?,Schizophyllum C?12?,cerevisterol?13?,cyathisterone?14?,of which,?10?,?11?and?12?were new sesquiterpenoids.Compound 11 showed weak inhibitory effect against Staphylococcus aureus.Seven compounds were isolated from the fermentation broth of Peethambara sp.JY-66 and identified as pyrollidine L-657,398?15?,Peethambara A?16?,Peethambara B?17?,Peethambara enamide?18?,1-methylcyclohexane-1,2,4-triol?19?,1-methylcyclohexane-1,2,4-trio A?20?,ergosterol?21?.Among of them,16,17 18 and 20 were new compounds.Compounds 15 and 16 showed inhibitory effect against Staphylococcus aureus,Candida albicans,Ralstonia solanacearum,Verticillium dahliae Kleb,Fusarium oxysporum f.sp.niveum,Fusarium oxysporum f.sp.cubense,Fusarium oxysporum f.sp.vasinfectum respectively.Compounds 15,16,18 exhibited cytotoxic activities in vitro against SGC-7901 tumor cell lines with IC₅₀ values of 33.1,63.1,89.4 mM,respectively,exhibited cytotoxic activities in vitro against BEL-7402 tumor cell lines with IC₅₀ values of 52.4,80.8,91.4 mM,respectively and exhibited cytotoxic activities in vitro against K-562 tumor cell lines with IC₅₀ values of 15.5,26.7,80.4 mM,respectively.Compound 15 also showed acetylcholinesterase inhibitory activity.