Study On Secondary Metabolites And Biological Activity Of Chaetomium Sp.strain Based On OSMAC Strategy

In this study,the endophytic fungus Chaetomium globosum was isolated from the leaves of Ginkgo biloba in the previous research of our group.The OSMAC strategy was used to select the medium formula and the type of its chemical inducer.The strain was fermented with oat solid fermentation and the liquid medium pre-screened by our group.The ethyl acetate fraction of the ferment was separated and purified by silica gel,sephadex LH-20 gel and Rp-C18 gel column chromatography and thin layer chromatography.The isolated compounds were identified by mass spectrometry(EI-MS,ESI-MS)and NMR(1H-NMR,13C-NMR)spectroscopy techniques,and the compounds were tested for algae inhibition activity,allelopathic activity and nematicidal activity.The results are as follows:(1)Five compounds numbered I-V were isolated from the ethyl acetate extraction portion of the oat solid medium and were identified as: brefeldin A(I),cytochalasin J(II),di-2-ethyl hexyl phthalate(III),zygosporin D(IV),7-O-?-D-galactosyl-brefeldin A(V).(2)Seven compounds numbered VI-XII were isolated from the ethyl acetate extraction portion of the liquid medium and identified as: cytochalasin B(VI),cytochalasin N(VII),cytochalasin H(VIII),19,20-Epoxyctochalasin-Q(IX),chaetoglobosin A(X),ergosterol peroxide 19-0-acetylchaetoglobosin A(XI),chaetoglobosin C(XII).These compounds all belong to alkaloid compounds.(3)The algae inhibiting activity of two algae was tested by chlorella vulgaris method: brefeldin A(I),cytochalasin J(II),cytochalasin B(VI),chaetoglobosin A(X),chaetoglobosin C(XII).The results showed that chaetoglobosin A(X)(10?g/ml)had a significant inhibitory effect on chlorella vulgaris,and the inhibition rate 76.82%.The allelopathic activity of the nine plant seeds was tested by the culture method of the compound: brefeldin A(I).The results showed that: brefeldin A(I)(5?g/m L)completely inhibited the two weeds of Portulaca oleracea L.and Plantago depressa Willd.rooting and germination,the RI value is-1,-1 and it has a certain promoting effect on the rooting and germination of radish seeds.The nematicidal activity test showed that brefeldin A(I)is inactive against Caenorhabditis elegans.In summary,this study based on the OSMAC strategy to isolate 15 compounds from a C.globosa,identified 12 compouds,several of which have algae-inhibiting activity and allelopathic activity,no nematicidal activity.The C.globosa has been shown to have the potential to be developed into bioherbicides.