Studies On The Secondary Metabolites And Bioactivities Of Mangrove Endophytic Fungi 30# And THSH-3#

Mangrove is a woody plant community located at the junction of the mainland and the sea.Due to its unique geographical location and special ecological environment such as high salt and little nutrition,mangrove plants have created biodiversity and abundant symbiotic biological resources of mangrove plants,enjoying the reputation of"marine forest".There are many kinds of endophytic fungi in mangrove plants,which are an important part of marine microorganisms.A large number of studies at home and abroad have reported that there are a large number of novel compounds with rich structure and good activity in the secondary metabolites of mangrove endophytic fungi,which can provide structural guidance for the development of new drugs.Therefore,the research direction of natural products of mangrove endophytic fungi has attracted more and more attention of researchers at home and abroad.In this thesis,two strains,Talaromyces amestolkiae 30#and Alternaria alternata THSH-3#.In this paper,OSMAC strategy was adopted to optimize the rice solid medium with nitrogen source as the fermentation method.The mangrove fungus Talaromyces amestolkiae30#and the mangrove fungus Alternaria alternata THSH-3#;The chemical structure of its secondary metabolites was analyzed and identified by NMR,MS and X-ray single crystal diffraction.A total of 21 monomeric compounds were isolated from these two mangrove endophytic fungi in this thesis.Among them,16 compounds were obtained from the fungus Talaromyces amestolkiae 30#,6-(2-(2,4-dihydroxy-6-methylphenyl)-2-oxoethyl)-2,4-dihydroxy-3-methylbenzoic acid(1),platencin SL1(2)?4-hydroxy-platencin SL1(3)?hypoxyterpoid A(4)?phomoxanthones A(5),butyrolactone I(6),graphislactone a(7)6-hydroxy-8-methoxy-3-methylisocoumarin(8),sclerotinin a(9),5,6,8-trihydroxy-4-(1?-hydroxyxyl)isocoumarin(10),sescandelin(11),aspergillumarins a(12),o-hydroxyphenylacetone(13),4-hydroxy-2-methoxyatanilide(14),a-parametric acid(15),tyrosol(16).There are five compounds derived from the fungus Alternaria alternata THSH-3#,which are 6-epi-stephytriol(17),alteroxin(18),stephyerlenol(19),ML204(20)and alteruene(21).By searching Sci Finder database and comparing with literature,compound 1 was a new compound,and compound 20 was found from fungi for the first time.In this thesis,the isolated monomers were screened for antibacterial,antitumor and other biological activities.It was found that compounds 6 and 18 had weak cytotoxic activity against human hepatoma cell HepG2 cells,and their IC₅₀ values were 63.60 and 50.45 respectively?M;Compounds 5 and 18 had certain antibacterial activity against Staphylococcus aureus,and their MIC values were 25?M and 50?M.Compound 5 has weak antibacterial activity against Bacillus subtilis,and its MIC value is 50?M.In addition,DPPH method was used to screen the antioxidant activity of some monomers in vitro:at the concentration of 100?M,compounds 6 and 10 had good antioxidant activity,and their free radical scavenging rates were87.2%and 54.1%respectively.In this thesis,two strains of secondary metabolites from mangrove endophytic fungi were studied.The results enriched the natural product database of marine microorganisms and provided a theoretical reference for the study of active secondary metabolites of marine fungi.