In vitro and in silico Investigation of Bioactive Compounds from Arcangelisia flava (L.) Merr. as Potential Antibacterial Agents
The growing threat of antibiotic resistance has prompted the hunt for new antibacterial medicines derived from natural sources. This work examined four compounds isolated from Arcangelisia flava (L.) Merr. roots: palmatine (1), fibraurin (2), β-sitosterol (3), and daucosterol (4). Both in vitro and in silico methods were used to assess their antibacterial properties. The antibacterial activity was assessed against Staphylococcus aureus, Bacillus subtilis, Vibrio alginolyticus, and Salmonella typhimurium using the broth microdilution method, which determined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Palmatine (1) and fibraurin (2) had modest action against Gram-positive bacteria, with MIC values of 37.5 µg/mL. However, β-sitosterol (3) and daucosterol (4) showed lesser inhibition. Docking against bacterial protein targets (PDB IDs: 2ZDQ and 1HNJ) found palmatine (1) had the highest binding affinity (−7.7980 and −7.5464 kcal/mol, respectively), generating numerous hydrogen bonds and hydrophobic interactions. Pharmacophore analysis identified critical structural features - aromatic rings and hydrogen bond donors/acceptors - that are linked to the observed antibacterial activities. Palmatine (1) and fibraurin (2) met drug-likeness criteria, but β-sitosterol (3) and daucosterol (4) had limited absorption and potential for toxicity. Overall, (1) and fibraurin (2) are intriguing lead candidates for antibacterial drug development, requiring additional in vivo testing and structural tweaking to improve efficacy.