Chromatographic separations and characterization of bioactive secondary metabolites of Apergillus quadrilineatus (MH109538) fungal strain

Abstract

In the interest of searching new antibiotic substances, the antibacterial effect of Aspergillus quadrilineatus fungal strain (MH109538) has been evaluated against sensitive bacteria (S. aureus, E. faecalis, B. subtilis and E. coli) and resistant bacteria (P. aeruginosa and K. pneumonia), following the disks technique. The obtained result confirms the capacity of this strain to produce antibacterial molecules. In order to analyze and characterize these bioactive metabolites present in the crude extract, which was fractionated by column chromatography. The fractions were then separated by thin-layer chromatography. The detected spots were sampled and tested against the most sensitive bacteria (S. aureus). The results have revealed that only one fraction showed an antibacterial activity. This active fraction was analyzed by liquid chromatography coupled with mass spectrometry (LC/MS) in order to obtain the elemental composition of the present compounds. The molecular ions fragmentation (LC/ MS/MS) were used to determine the deployed formula of these compounds. The analysis of the results by Xcalibur 2.2 software reveals the presence of 24 molecules, and this, based on the retention times of the peaks obtained in the chromatogram, where, the m/z ratios, the formulas, as well as the intensities of the various compounds detected are determined.