Preliminary Study On Secondary Metabolites Of Two Cockroach Gut Endophytic Actinomycetes

In the early stage of the research group,two strains of actinomycetes(Gardenella strain WA12-1-1,Streptomyces sp.WA23-4-4)were found in the antibacterial and antifungal activity tests of the ethyl acetate extract isolated from the gut endophytic actinomycetes.The ethyl acetate extract has various degrees of antibacterial and antifungal inhibitory activity.Therefore,this thesis carried out research on secondary metabolites of strains WA12-1-1 and WA23-4-4,aiming to find compounds with novel structure and good biological activity.The crude extract of ethyl acetate and the crude extract of mycelium of the fermentation broth of strain WA12-1-1 were carried out by various chromatographic methods such as silica gel,ODS,MCI,Sephadex LH-20 and semi-preparative high-performance liquid phase.The systematic chemical composition research was carried out,and their structures were determined by UV spectroscopy,nuclear magnetic resonance and mass spectrometry.As a result,11 compounds were isolated from the crude extract of ethyl acetate.1 triterpenoid: 2-Hydroxy-3-oxooleana-1,12-dien-28-oic acid(1);six alkaloids Compound:(2E)-2-methyl-2-butenamide(2),quinazolin-4(3H)-one(3),2-(acetylamino)benzamide(4),2-Methyl-4(3H)-quinazolinone(6),(p-hydroxyphenyl)acetamide(8),(5,6)-dihydro-2,4(1H,3H)-pyrimidinedione(14),uridine(18);1 phenylpropanoid: 3'-(4''-hydroxy-3''-methoxyphenyl)-propyl benzoate(5);2 cyclic dipeptides:Cyclo-(Ala-Pro)(13),Cyclo(L-Gly-L-Pro)(15);.Nine compounds were isolated from the crude extract of mycelium ethyl acetate: two alkaloids:2-phenylacetamide(7),2-(acetylamino)benzamide(18);six cyclic dipeptides a compound: Cyclo(D-Phe-L-Pro)(9),Cyclo-(L-Pro-L-Phe)(10),Cyclo(Phe-Ile)(11),Cyclo-(L-Phe-L-Leu)(12a),Cyclo-(Leu-Leu)(12b),cyclo-(L-pro-L-tyr)(16),cyclo(L-Pro-L-Val)(17),cyclo-(S-ProR-Leu)(19).Compounds 1,2,and 3 are new natural products,and compounds 2,4,and 6 are the first isolates of actinomycetes,and the remaining compounds are isolated for the first time in the genus Gordonia.The experimental tests tested the antibacterial,antifungal and antitumor activities of some compounds.The new natural product compounds 1,2,3and 4,5,6 were resistant to methicillin-resistant Staphylococcus aureus,Staphylococcus aureus and Escherichia coli.The bacteria and Candida albicans showed effective and different degrees of antagonism,and also had different degrees of proliferation inhibition effects on tumor cell lines CNE-2,MCF-7,A549 and Hela cells.Using silica gel,ODS,MCI,Sephadex LH-20,semi-preparative high-performance liquid chromatography and other chromatographic methods,the systematic chemical constituents of the crude extract of the fermentation broth of strain WA23-4-4 were studied and passed.Their structures were determined by UV,NMR and MS.As a result,11 compounds were isolated from the fermentation broth of strain WA23-4-4,and their structures were determined by UV spectroscopy,nuclear magnetic resonance and mass spectrometry: 8 cyclic dipeptide compounds:Cyclo(L-Pro-L-Val)(20),Cyclo(S)-Pro-(S)-Ile(21),cyclo-(R-pro-R-leu)(22),Cyclo-(L-pro-L-tyr)(23),cyclo(Gly-Leu)(24),Cyclo(Ala-Tyr)(25),Cyclo(Ala-Val)(29a),Cyclo(Gly-Ile)(29b),three alkaloids: trans-pHydroxycinnamic acid(26),2-aminobenzoic acid(27),N-[2-(4-hydroxybenzoic)-ethyl] acetamide(28);.Compound 25 was isolated for the first time in actinomycetes,and compounds 26,27,and 28 were first isolated from endophytic actinomycetes in the gut,and other compounds were the first to separate compounds 26,27,and 28 in endophytic Streptomyces.It is the first separation in the gut endophytic actinomycetes.The antibacterial,antifungal and antitumor activities of some of the compounds were determined experimentally,and the compounds 20,21 and 24 exhibited good selective antibacterial,antifungal and antitumor activities.The results showed that the endophytic actinomycetes WA12-1-1and WA23-4-4 in the gut were more abundant in antibacterial compounds and worthy of further systematic research.