engleski

ANTIMICROBIAL ACTIVITY OF PROPOLIS AND GALANGIN (3, 5, 7-TRIHYDROXYFLAVONE) AGAINST MRSA, MULTIPLE-RESISTANT ENTEROCOCCUS spp. AND PSEUDOMONAS AERUGINOSA

Many plant-derived substances have antimicrobial activity and plants present good models for searching novel antimicrobials, especially against multi-resistant bacteria. Propolis is resinous substance collected by honeybees from various trees and possesses many biological activities. Spectrum of antimicrobial activity of propolis ethanolic extracts (PEE) is wide: bacteria, yeasts and dermatophytes. Substances with antimicrobial activity in propolis are: flavonoids (galangin, pinocembrin), esters of caffeic acid and essential oil components. In this research we have tested 3 samples of propolis collected from Croatia against clinical isolates of resistant bacteria: MRSA (n=10), multiple-resistant Enterococcus spp. (n=17) and Pseudomonas aeruginosa (n=10). Clinical isolates of MSSA and Salmonella spp. are also tested. In diffusion assay, all samples of PEE exhibited activity against Staphylococcus aureus strains with inhibition zones max. 20.6 mm&plusmn ; 2.5 (mean&plusmn ; SD) ; Enterococcus spp. strains and P. aeruginosa strains max. 15 mm&plusmn ; 1.9. PEE have no activity on Salmonella spp. In macrobroth two-fold dilution assay MIC&#8217 ; s values exhibited range from 1.06 to 4.98 mg/mL for MRSA strains ; 2.33 to 9.09 mg/mL for Enterococcus spp. strains and 7.63 to 14.16 mg/mL for P. aeruginosa strains. Results show differences in antimicrobial activity among three PEEs which depends on concentration of antimicrobial compounds. Antimicrobial-activity-guided assay (bioassay in situ on developed TLC plates with Bacillus subtilis NCTC 8236 or &#8220 ; autoantibiogram&#8221 ; ), that allows localization of bactericidal constituents in PEE, showed that flavonoid galangin (3, 5, 7-trihydroxyflavone) is compound with the strongest antimicrobial activity.

propolis; galangin; multi-resistane bacteria; MRSA; Enterococcus; Pseudomonas aeruginosa

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