In Vitro Antimicrobial Activity of (Pink Water Lily) Leaf Extracts.

This research comparatively investigates the in vitro antimicrobial activity of extracts from (pink water lily) leaves against pathogenic bacteria. The experimental extracts are aqueous, acetonic, and 95% ethanolic extracts; and the pathogenic bacteria being studied include , , , and , which are commonly found in freshwater fish and brackish aquatic animals. The ethanolic extract achieves the highest bacterial inhibitory effects against and . The minimum inhibitory concentrations of the ethanolic extract against and are 10 mg/mL; and 2.5 mg/mL against and . The ethanolic extract is effective against . The high-performance liquid chromatography results show that, in the phenolic acids group, gallic acid is the most dominant (0.600-3.21% /), followed by sinapic acid (0.37-0.83% /). In the flavonoids group, catechin is the most dominant (0.02-1.08% /), followed by rutin (0.002-0.03% /). Essentially, the ethanolic extract can potentially be used as a natural antibiotic agent to treat bacterial infections in fish and aquatic animals.