Antimicrobial Activity of Flueggea leucopyrus Willd (Katupila) Leaf Extracts against Some Common Milk Pathogens

Abstract

Flueggea leucopyrus Willd is a natural herbal plant native to Sri Lanka with great ayurvedic therapeutic potential, and this study assessed the antimicrobial activity of methanolic extracts of F. leucopyrus Willd against some common milk pathogens including S. aureus (ATCC 25923), P. aeruginosa ( ATCC 27853), Salmonella spp., and E. coli (ATCC 25922). Agar well di usion assay was implemented for the assessment of in-vitro antibacterial potency. The Minimal Inhibitary Concentration (MIC) was determined using the agar broth macro dilution technique as well as Minimal Bactericidal Concentration (MBC) was also performed. The 400 mg/ml extract showed the highest antibacterial activity against S. aureus with a zone of inhibition (ZOI) of 28.0 1.0 mm (p > 0.05) without signi cantly altering from the positive control, gentamicin (28.3 0.6 mm). A ZOI of 27.0 1.0 mm, which was higher than that of the positive control (26.7 0.6 mm) was exhibited against E. coli at a concentration of 400 mg/ml, did not di er signi cantly (p > 0.05) from the control. Inhibition zones were also observed for concentration of 200, 100, 50, and 25 mg/ml against S. aureus and E. coli, but signi cantly lower (p < 0.0001) compared to controls. Only the 400 mg/ml extract inhibited the growth of Salmonella spp. ZOIs were also observed against P. aeruginosa with the concentration of 400, 200, and 100 mg/ml but comparatively low. The mean MBC values ranged from 16.7 mg/ml to 400 mg/ml, with values against S. aureus, P. aeruginosa, Salmonella spp., and E. coli were 16.7 7.2 mg/ml, 66.7 28.9 mg/ml, 400 0.0 mg/ml, and 20.8 7.2 mg/ml, respectively. These preliminary observations demonstrate the e ective antimicrobial activity of Katupilaas a natural antibacterial agent for milk and milk products and suggest the prospect of using them in drugs to treat infectious illnesses caused by the tested microorganisms.