Abstract
The alkaloid leaf fraction of Newbouldia laevis, a plant widely used in traditional medicine for wound healing and infection control, was evaluated for its antioxidant and antibacterial activities alongside molecular docking analysis to predict possible mechanisms of action. Antioxidant capacity was assessed using hydroxyl radical, nitric oxide, DPPH radical scavenging, and lipid peroxidation inhibition assays. Antibacterial activity was tested against Staphylococcus aureus, Salmonella typhi, Pseudomonas aeruginosa, and Escherichia coli using agar well diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) methods. The extract showed strong, concentration-dependent radical scavenging effects, reaching maximum inhibition at 320 µg/mL, particularly in DPPH (79.10%) and lipid peroxidation (86.90%) assays. IC₅₀ values ranged from 92.70 µg/mL for DPPH to 382.90 µg/mL for hydroxyl radicals, confirming substantial antioxidant potential. The antibacterial result showed dose-dependent inhibition, with S. aureus showing the highest susceptibility (14.90 mm inhibition zone at 400 mg/mL). Bactericidal effects were observed at 50 mg/mL against all organisms, indicating both bacteriostatic and bactericidal actions, with Gram-positive bacteria showing greater sensitivity. The findings validate the ethnomedicinal use of N. laevis and highlight its potential as a source of lead compounds for developing plant-based therapies against oxidative stress and bacterial infections.