Mass spectrometric profile, antioxidant and oral pathogen biofilm control capacity of small molecules from an endophyte Cladosporium species: In vitro and in silico models

Abstract

The aim of the present study is to showcase the antimicrobial potential of compounds derived from the endophytic fungus Cladosporium spp. Cladosporium sp. was isolated and identified from healthy seed tissue of Solanum violaceum Ortega. Cell-free supernatant was subjected to solvent extraction and examined on the human oral cavity pathogens, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Candida tropicalis. Liquid and Gas Chromatography-Mass Spectra (LC-MS and GC-MS) identified compounds was blind docked using a variety of targets of the tested pathogen. The user friendly CB dock-2 version 1.1.2, SwissADME tool, SwissTargetPrediction, Absorption, Distribution, Metabolism and Excretion (ADME), drug-likeness and Lipinski’s rule of five, ligand and protein structures from PubChem and Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB) respectively were used to perform the blind docking. Among the solvents used, n-butanol was the best and showed a broad-spectrum antimicrobial activity. n-butanol extract showed inhibition zones of 16±0.2 (S. aureus), 15±0.1 (E. coli), 16±0.1 (K. pneumonia) and 15±0.1 (C. tropicalis). Microbicidal activity was observed within 20–24 h (p<0.05). S. aureus showed increased protein release (4–8 h), while C. tropicalis exhibited none in the first 4 h. The minimum required inhibitory concentration was in the range of 1 mg/mL to 4 mg/mL. The antioxidant activity ranged from 47.9 % to 68.7 % measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Genomic DNA degradation was noted in E. coli, S. aureus, and K. pneumoniae and significant biofilm reduction (p<0.003) and no patchy colonies were noted in the treated set. This result proves that the compound is affectively acting on the cell membrane and DNA. Spectrophotometry identified several antimicrobial and antioxidant compounds including Paramomine, Sphinganine, 2”-deamino-2”-hydroxyneamine (3+), Alpha-amylcinnamaldehyde, Netilmycin, 13-Desoxypaxilline, Pyridine, Gamma Butyrolactone, Levoglucosenone, 1.3-Diaxolane, 4-Chloro-1-butanol, DMSO and Furan. All the GC and LC-MS compounds have obliged the Lipinski’s rule of five, except Paramomine and Netilmycin. The Brain or IntestinaL EstimateD permeation method (BOILED Egg) prediction indicated that the majority of the compounds are absorbed in Gastro Intestinal or to the brain. The ligand binding capacities varied from organism to organism. To conclude, n-butanol extracts of Cladosporium sp., are ideal candidates for controlled dividing capacity of oral pathogens.