Studies On The Secondary Metabolites Of One Medical Plant Hypericum Beanii From Hypericum Genus And Four Fungi

The content of this article is divided into five chapters.The first four chapters describe the research results of secondary metabolites from the plant endophytic fungus Pestalotiopsis theae,marine coral symbiotic fungus Stachybotrys chatarum,and marine Penicillium sp.TJ403-1 and Penicillium citrinum,and the plant Hypericum beanii from Hypericum genus.Chapter five summarizes the research progresses on the chemical structures and biological activities of a series of phloroglucinol derivatives synthesized with chinesin?and its analogues as biogenic precursors.As an important group of endophytic fungi,Pestalotiopsis species can produce a variety of biologically active secondary metabolites.We isolated a strain of Pestalotiopsis theae from tea leaves in Enshi Prefecture.After cultivation on solid rice media,a total of 20compounds(1-4,(±)-5,6-19),including 7 new compounds(1-4,(±)-5,6),were obtained.The structure types of these compounds mainly included crotonolactone,biphenyl and its derivatives,etc.,and their structures were determined by NMR,UV,IR,ECD calculation,optical rotation analysis and data comparison with the known compounds.After determining their absolute configurations,we tested some compounds for cytotoxic activity.The test cell lines include human tumor HL-60,U87MG,MDA-MB-231,A-549,HEP-3B and SW-480 cell lines,and a non-cancerous NCM460 cell line.Among them,compound 1showed significant cytotoxic activity against human tumor HL-60,U87MG,MDA-MB-231,and HEP-3B cells,with IC₅₀values of 1.42,5.90,5.90 and 4.29?M,respectively.Compound 4 showed significant cytotoxicity against HL-60 cell lines,with an IC₅₀value of5.05?M.Due to their unique growth environments(high salinity,high pressure,etc.)and genetic metabolic mechanism,marine-derived microorganisms have always been an important source for the discovery of novel active secondary metabolites and a strong driving force for the development of new drugs.We conducted a systematic study on the secondary metabolites and biological activities of the epiphytic fungus Stachybotrys chartarum collected from the coral reefs of the South China Sea.A total of 16 compounds were isolated and identified from the ethanol extract of the rice solid medium(20-35),including8 new compounds(20-27),and the absolute configurations of compounds 20-25 were determined by single crystal X-ray diffraction.Among them,atranone Q(23)is the first C₂₃atranone featuring a propan-2-one motif linked to a dolabellane-type diterpenoid by a carbon-carbon bond;atranone R(24)is the first example of a C₂₄atranone with a2-methyltetrahydrofuran-3-carboxylate motif fused to a dolabellane-type diterpenoid at C-5-C-6.Subsequently,the in vitro antimicrobial activities against?-lactamase(ESBL)-producing escherichia coli,acinetobacter baumannii,Pseudomonas aeruginosa,methicillin-resistant Staphylococcus aureus(MRSA),Enterococcus faecalis and Candida albicans were evaluated for six dolabellane-type diterpene derivatives(20-25).The results showed that 21 had inhibitory effects against Acinetobacter baumannii and Enterococcus faecalis,with MIC values of 16 and 32?g/m L,respectively;compound 23 had significant inhibitory effect against Candida albicans,with MIC values of 8,16 and 32?g/m L.Through further scanning of transmission electron microscope,it can be observed that compound 23 had a significant damaging effect on the cell wall and cell membrane of resistant Candida albicans strain at a concentration of 16?g/m L.In addition,we have isolated Penicillium sp.TJ403-1(an unnamed fungus of the genus Penicillium,and we defined it as Penicillium based on the analysis of its morphology and DNA sequence)from the tissues of soft corals of the genus Alcyonium in Sanya,China and Peniciliium citrinum from the 7000-meter sea test area of the Atlantic Ocean.A total of 25compounds(36-60)were isolated and identified,including 2 new compounds(28 and 33):one breviane type compound(36)and a citrinin dimer(47).The absolute configurations were determined by comparing the ECD curves of known compounds.The results on the antitumor and IDH1 inhibitory activity of the secondary metabolites of Penicillium sp.TJ403-1 showed that compound 37 showed cytotoxic activity against HL-60,A-549 and HEP-3B tumor cell lines,with IC₅₀values of 4.92±0.65,8.60±1.36 and 5.50±0.67?M,respectively.Our research group has been committed to the study of the chemical and pharmacological diversities of Hypericum plants in Central China.We have performed a chemical investigation on the 95%ethanol extracts of Hypericum beanii collected from Enshi,Hubei Province.As a result,a total of 36 phloroglucinol derivatives and 5 xanthrone derivatives(61-101)were separated and identified,of which 17 ones were new compounds(61-77),including seven compounds(61-66 and 69)featuring new skeletal types.Considering the biogenic pathways,the structures of all the isolated phloroglucinol derivatives can be divided into three categories:2,3-seco PPAPs(61-68),5,6-seco PPAP(69),and octahydrospiro-[cyclohexan-1,5'-indene]spirocyclic PPAPs(70-76)of the parent nucleus.Compounds 61-64 are 2,3-seco type PPAPs containing six-membered?-lactone units isolated for the first time.The absolute configuration of compound 61 was determined by X-ray single crystal diffraction and ECD calculation.The absolute configurations of compounds 62-63 were determined by DP4+possibility analysis based on carbon spectrum calculation and ECD calculation.Compounds 65-66 are 2,3-seco type PPAPs containing?-lactone units isolated for the first time.The absolute configuration of compound 65 and 66was defined through X-ray diffraction and comparison of the ECD curves.Compound 69was the first reported 5,6-seco PPAP,which contained a unique benz[f]indene-1,9(4H)-dione core structure.Its planar structure and absolute configuration were defined by comprehensive use of spectroscopy,DP4+probability prediction based on¹³C NMR calculation,and ECD calculation.Compound 70 was the first identifed spiro PPAP with intramolecular dehydration to form a 6/6/6/5 ring system,which forms an oxygen bridge between C-3 and C-12 in the molecule,and its absolute configuration was confirmed through single crystal X-ray diffraction.Compound 71 was a 2,27-seco spiro PPAP isolated for the first time,and its absolute configuration has been determined by ECD calculation.Some phloroglucinol derivatives were screened for cytotoxic activity in vitro,and the results showed that compounds 69,70 and 82 had certain cytotoxity.In this paper,we have carried out a systematic study on the secondary metabolites of plant-derived endophytes,marine-derived fungi and medicinal plant Hypericum beanii.We use spectrum analysis,ECD calculation,DP4+analysis based on carbon spectral data,and single crystal X-ray diffraction and other methods to determine the absolute configuration of many natural products including polyketones,alkaloids,diterpenes,heteroterpenes,and phloroglucinol derivatives.