Acacia gerrardii, a desert plant as a sustainable source of natural products with antimicrobial properties

The aim of this study was to determine the chemical composition of methanolic extracts obtained from Acacia gerrardii (Benth.) leaves collected from the Hail Region of Saudi Arabia, to identify new bioactive compounds, and to their antioxidant activities, antibacterial and antifungal potentials, and their mineral composition. The methanolic extract showed the highest inhibition zone against methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae and Escherichia coli. This activity is dose dependent. MIC and MBC values obtained against these bacteria in the presence of the extract were 3.125 and 50 mg/mL, respectively. The antifungal activity showed low effect against all the tested fungi (MIC: 6.25 mg/mL, MBC: 25 mg/mL). GC-MS analysis revealed the presence of 15 potent compounds. 4-O-Methylmannose was determined as the main compound of the methanolic extract. Omega 3 and 9 fatty acids, as well as diterpene and sterols were also characterized in the extract. Forty-nine (49) compounds were identified by HR-LC/MS, the main identified classes are amino acids, alkaloids, flavonol, flavones, flavonoids, dipeptide, indoles, stilbenes, pyrans, terpenes, glycosides, and sphingolipids. Moreover, the computational study revealed that the compounds identified in A. gerrardii extract binds to TyrRS from S. aureus (1JIJ), and the secreted aspartic proteinase 1 from C. albicans (2QZW) receptors with acceptable affinities and interactions. The rich phytochemical composition might be the cause of the outlined pharmacokinetic properties and molecular interactions associated antimicrobial effects, as reported by both computational and in vitro studies.