Integrating NMR-based Metabolomics And The MyxoDB Database To Facilitate The Mining Of Natural Products From Myxobacteria

Microbial natural products are a valuable resource for drug discovery,with myxobacteria being a particularly promising source due to their large genomes and ability to produce diverse secondary metabolites including compounds with unique structures and high activity such as epothilone.Despite their potential,repeated discoveries of known compounds present a challenge in exploring their full potential.Implementation of comprehensive natural product databases can effectively facilitate the de-duplication process.While there are natural product databases available for certain species,such as PAMDB and StreptomeDB.an open-source myxobacterial natural product database has not yet been established.To address this gap,we have compiled published literature and internal laboratory data to create the first open-source myxobacterial natural product database,MyxoDB(https://www.myxonpdb.sdu.edu.cn),which includes statistical analysis tools to aid in the de-duplication of myxobacterial natural products.In addition,nuclear magnetic resonance metabolomics offers a robust dimensionality reduction analysis capability that can be utilized for systematic highthroughput analysis of crude extracts and targeted identification,greatly facilitating strain selection and the exploration process.This paper seeks to combine the power of nuclear magnetic resonance metabolomics with the MyxoDB database to enable efficient and targeted exploration of myxobacterial natural products.The specific objectives of this research include:Through high-throughput nuclear magnetic resonance characterization of fermentation products from 147 myxobacterial strains,novel potential strains with unique natural products were identified based on principal component analysis.One such strain was Archangium gephyra SDU49,a rare myxobacterium isolated from desert soil.Through 2D NMR analysis,specific signals were identified and substructure searches were conducted in MyxoDB.revealing that this substructure did not correspond to any known myxobacterial natural product,indicating that it may be a promising novel natural product.Guided by the nuclear magnetic resonance probe,targeted isolation was performed,leading to the identification of archangiumin and insights into their biosynthesis pathways and biological activities.Moreover,Archangium sp.SDU34,another rare myxobacterium isolated from desert soil.displayed complex secondary metabolite components in its fermentation product.Through isolation and identification,two pyridine myxochelin compounds were obtained.Their novelty was determined through the database,and their structures were confirmed by NMR,MS,IR,and their biosynthesis pathways were deduced and verified.Two new compounds were identified through precursor feeding experiments using MS secondary fragmentation comparison.Additionally,Corallococcus sp.SDU78 demonstrated potent inhibition effects on Staphylococcus aureus in its fermentation products as detected by HPLC-DAD analysis.With the aid of the MyxoDB database,early-stage preliminary structure determination of target compounds was successfully accomplished.During the subsequent isolation process,Corallopyronin compounds and two siderophore compounds were isolated.Their structure was identified through 2D NMR,spectral data comparison,and literature reports.However,due to poor stability,further exploration is required for Corallopyronin.