COMPARATIVE ANALYSIS OF THE BACTERICIDAL AND ANTIBIOTIC MODULATORY ACTIVITIES OF THE STEM BARK EXTRACTS OF GMELINA ARBOREA ROXB AND OROXYLUM INDICUM (L.) KURZ

Medicinal plants play pivotal roles in novel drug discovery or combinatorial drug surveillance against emerging infectious diseases. This study aims to explore and compare the bactericidal and antibiotic modulating activities of stem barks of Gmelina arborea Roxb. and Oroxylum indicum (L.) Kurz against two pathogenic bacterial strains, i.e., Escherichia coli and Staphylococcus aureus. Methanolic stem bark extracts of G. arborea and O. indicum were subjected to phytochemical analysis, DPPH antioxidant assay, and varieties of antibacterial assays (disc diffusion, agar well diffusion, modified agar well diffusion, and bacterial cell viability), and the results were compared. Phytochemical analysis revealed that both plants had major bioactive compounds like alkaloids, terpenoids, phenol & tannins, steroids, glycosides, etc. G. arborea had a total phenol content (TPC) of 27.33±8.60 mg/g of Gallic Acid Equivalent (GAE) and a total flavonoid content (TFC) of 72.33±4.90mg/g of Rutin Equivalent (RE). At the same time, O. Indicum was calculated to have a TPC of 48.58±1.80 mg/g of GAE and TFC of 269±0.88mg/g of RE. Though both stem barks exhibited excellent antibacterial activities against both E. coli and S. aureus strains, O. indicum inhibited the growth of S. aureus better in comparison to E. coli by augmenting the bactericidal activity of conventional antibiotics like ampicillin, and nitrofurantoin, while G. arborea supplemented the activities of streptomycin, ampicillin, and cefixime against S. aureus. Our results may be beneficial in recommending G. arborea and O. indicum stem barks as alternatives or combination therapy with antibiotics to treat different bacterial infections.