Combining OSMAC Approach and Untargeted Metabolomics for the Identification of New Glycolipids with Potent Antiviral Activity Produced by a Marine Rhodococcus.

Natural products of microbial origin have inspired most of the commercial pharmaceuticals, especially those from Actinobacteria. However, the redundancy of molecules in the discovery process represents a serious issue. The untargeted approach, One Strain Many Compounds (OSMAC), is one of the most promising strategies to induce the expression of silent genes, especially when combined with genome mining and advanced metabolomics analysis. In this work, the whole genome of the marine isolate Rhodococcus sp. I2R was sequenced and analyzed by antiSMASH for the identification of biosynthetic gene clusters. The strain was cultivated in 22 different growth media and the generated extracts were subjected to metabolomic analysis and functional screening. Notably, only a single growth condition induced the production of unique compounds, which were partially purified and structurally characterized by liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). This strategy led to identifying a bioactive fraction containing >30 new glycolipids holding unusual functional groups. The active fraction showed a potent antiviral effect against enveloped viruses, such as herpes simplex virus and human coronaviruses, and high antiproliferative activity in PC3 prostate cancer cell line. The identified compounds belong to the biosurfactants class, amphiphilic molecules, which play a crucial role in the biotech and biomedical industry.

Soybean-associated endophytic fungi as potential source for anti-COVID-19 metabolites supported by docking analysis.

AIMS: To identify the metabolites produced by the endophytic fungus, Aspergillus terreus and to explore the anti-viral activity of the identified metabolites against the pandemic disease COVID-19 in-silico. METHODS AND RESULTS: Herein, we reported the isolation of A. terreus, the endophytic fungus associated with soybean roots, which is then subcultured using OSMAC approach in five different culture media. Analytical analysis of media ethylacetate extracts using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) was carried out. Furthermore, the obtained LC-MS data were statistically processed with MetaboAnalyst 4.0. Molecular docking studies were performed for the dereplicated metabolites against COVID-19 main protease (Mpro ). Metabolomic profiling revealed the presence of 18 compounds belonging to different chemical classes. Quinones, polyketides and isocoumarins were the most abundant classes. Multivariate analysis revealed that potato dextrose broth and modified potato dextrose broth are the optimal media for metabolites production. Molecular docking studies declared that the metabolites, Aspergillide B1 and 3a-Hydroxy-3, 5-dihydromonacolin L showed the highest binding energy scores towards COVID-19 main protease (Mpro ) (-9·473) and (-9·386), respectively, and they interact strongly with the catalytic dyad (His41 and Cys145) amino acid residues of Mpro . CONCLUSIONS: A combination of metabolomics and in-silico approaches have allowed a shorter route to search for anti-COVID-19 natural products in a shorter time. The dereplicated metabolites, aspergillide B1 and 3α-Hydroxy-3, 5-dihydromonacolin L were found to be potent anti-COVID-19 drug candidates in the molecular docking study. SIGNIFICANCE AND IMPACT OF THE STUDY: This study revealed that the endophytic fungus, A. terreus can be considered as a potential source of natural bioactive products. In addition to, the possibility of developing the metabolites, aspergillide B1 and 3α-Hydroxy-3, 5-dihydromonacolin L to be used as phytopharmaceuticals for the management of COVID-19.