In vitro and in silico properties of Rhododendron arboreum against pathogenic bacterial isolates

Abstract

The tree Rhododendron arboreum belongs to the Ericaceae family, which harbours the entire Himalayan range. In this study, flowers and leaves of R. arboreum were selected from the Mussoorie area in the district of Dehradun (Uttarakhand). Plant extracts were obtained by using hexane, distilled water, acetone, 80% methanol and ethyl acetate solvents in an orbital shaker. The activity of the extracts against Bacillus cereus, Shigella spp., Staphylococcus aureus, and Escherichia coli was investigated using an agar well diffusion procedure, and the synergistic interaction of the extracts with conventional antibiotics, including norfloxacin and ciprofloxacin, was examined. Phytochemicals of R. arboreum were obtained from PubChem, and a target protein was rebuilt using the RCSB protein data bank. The docking approach was carried out via AutoDock vina software with penicillin binding protein (3VSL) to validate the microbe interactions and bioactive molecules, whereas Molinspiration and Swiss ADME servers were used to determine the Lipinski rule of 5 and perform drug-likeness analysis, respectively. Protox II and AdmetSAR tools were used to screen phytoconstituent toxicity. Flower and leaf extracts exhibited the highest yields (3.06 ± 0.9% and 2.53 ± 1.01%, respectively) in methanol. Phenolics, alkaloids, carbohydrates, flavonoids, steroids, amino acids, cardiac glycosides, tannin, protein, and saponin were qualitatively found. Synergistic activity against B. cereus and E. coli was observed for aqueous leaf extracts, while methanol, ethyl acetate and aqueous extracts of flowers and leaves exhibited synergism against Shigella and S. aureus. Ethyl acetate extracts of flowers and leaves are the best synergistic enhancer. According to in silico data obtained from an in silico study, the best phytocompounds and prospective antibacterial agents are epifriedelanol and campanulin.