Vol. 9, Issue 12, Part A (2025)

The escalating threat of antimicrobial resistance demands novel, plant-derived therapeutics. This study evaluated methanolic and ethanolic extracts of shade- and oven-dried leaves and flowers of Nyctanthes arbor-tristis Linn. (Parijat) against clinically important pathogens: Cutibacterium acnes, Vibrio vulnificus, Aeromonas hydrophila, and Escherichia coli. Among three extracts (NAT-SLM: shade-dried leaf methanol; NAT-OLE: oven-dried leaf ethanol; NAT-SFM: shade-dried flower methanol), NAT-SFM exhibited the strongest activity. Disc diffusion zones ranged from 14.2±0.5 mm (E. coli) to 18.7±0.7 mm (C. acnes). Minimum inhibitory concentrations (MIC) of NAT-SFM were remarkably low (6.25-25 µg/mL), with MBC/MIC ratios ≤4 confirming bactericidal action. Time-kill kinetics demonstrated rapid killing, achieving ≥4.4-log₁₀ reductions within 24 h at 1-2× MIC across all strains. Phytochemical screening revealed high abundance of phenols/tannins and flavonoids in NAT-SFM. GC-MS analysis identified major bioactive compounds including myristic acid (4.57%), palmitic acid (4.48%), hexadecanol (3.08%), and 1-chloro-tetradecanamine (3.38%), known for membrane disruption, FabI inhibition, and efflux-pump blockade. Shade-drying and floral material proved superior to oven-drying and leaves, preserving heat-labile polyphenols and fatty acid derivatives. These findings validate traditional Ayurvedic use of Parijat flowers and position NAT-SFM as a promising natural alternative or adjuvant for acne therapy, wound infections, and aquaculture disease management, offering a sustainable solution against multidrug-resistant pathogens.