Studies On The Metabolites From The Strains Of Amycolatopsis Sp. And Kribbella Sp.

Actinomycetes are recognized as an important source for the discovery of novel active drugs,and their sources are in urgent need of expansion.As an important symbiotic community in the ecosystem,lichens occupy about 8%of the earth's surface and are mainly composed of symbiotic fungi and corresponding symbiotic algae.From an ecological and biological point of view,lichens not only grow in a special environment,but also have unique structural composition.These advantages allow lichens store valuable biologically active elements.However,the current researches on lichens are still limited.Moreover,the diversity and biological potential of lichen-related bacterial communities,especially lichen-associated actinomyces,had not yet been fully explored.Based on the above facts,six lichen-associated actinomycete strains are selected for antimicrobial screening,in which two bioactive strains Amycolatopsis sp.YIM130923 and Kribbella sp.YIM 130648 were choosed for further study.Based on the antibacterial tests and TLC detection,the suitable cultural conditions were optimized for expanded fermentation.Following by the fermentation of the two strains,a total of 21compounds were purified from the crude extract and identified by HRESIMS and NMR spectroscopy.They were identified to be N-((3R,4S)-4-methyl-2-oxotetrahydrofuran-3-yl)-2-phenylacetamide)(1),3-hydroxybutan-2-yl 3-(4-hydroxyphenyl)propanoate(2),(-)-2(E)-ethylidene-3(R)-methylsuccinimide(3),benzoic acid(4),benzeneacetic acid(5),3-phenylpropionic acid(6),2-propenoic acid(7),4-hydroxybenzenepropanoic acid(8),4-methoxybenzenepropanoic acid(9),4-methylphenyl ester(10),indole-3-aldehyde(11),indole-3-propionic acid(12),(1?,4?,5?,6?,7?,10?)-5,11-epoxy-10-cadinanol(13),(1?,6?)-11-eudesmanetriol(14),Cyclo(L-trans-Hyp-L-Leu)(15),cyclo(L-trans-Hyp-L-Phe)(16),cyclo(L-Pro-L-Leu)(17),(R)-2-amino-1-phenylethanol(18),1H-pyrrole-2-carboxamide(19),manalin(20),vermistatin(21).Compounds 1-14were derived from the strain Amycolatopsis sp.YIM 130923,and compounds 15-21were isolated from the strain Kribbella sp.YIM 130648.Among them,1 and 2 were new compounds.Compounds 13 and 14 belong to sesquiterpenes,which had been rarely reported in the genus Amycolatopsis.In this paper,compound 3 was mainly derived from algae and obtained from microorganisms for the first time.In addition,compound21 was mainly derived from the fungal genus of Penicillium and obtained from actinomycetes for the first time.This paper also conducted antimicrobial and antioxidant experiments on the identified compounds.Compound 14 revealed obvious inhibitory activity against Aspergillus niger and Fusarium graminearum,whose MICs were 32 and 16?g/mL,respectively.Compounds 9 and 13 can inhibit A.niger to a certain extent with MIC values of 64?g/mL.For inhibiting Salmonella typhi,the MIC value of compounds 14,15 and 17 were 64?g/mL,which showed the best antibacterial effect among all the compounds.In the DPPH assay,compounds 8,9,12,and 15 had a moderate antioxidant activity with the IC₅₀values of 41.62,74.93,69.18 and 82.31?g/mL,respectively.In this research,new compounds and antibacterial and antioxidant compounds had been obtained from lichen-derived rare actinomycetes of Amycolatopsis and Kribbella.It is worth noting that the current studies on metabolites of Kribbella were very few.The research results expand the structural types of the metabolites of rare actinomycetes,which provide the basis for further searching bioactive substances from actinomycetes.