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The flavonoid analysis and antimicrobial activity of commercially available propolis products

Propolis ethanolic solutions are the most often used propolis products on market for the treatment of minor ulcers in the mouth, angina, thrush or infections of the skin. Because it is still unofficial drug in pharmacy, we analysed the contents of flavonoids in the ten commercially available ethanolic solutions of propolis from Croatian market using two complementary colorimetric methods. Antimicrobial activity with diffusion method against six bacterial strains (Bacillus subtilis NCTC 8236, Staphylococcus aureus ATCC 25923, Staphylococcus pyogens ATCC 12204, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 10536, Pseudomonas aeruginosa ATCC 27853), and one yeast-like fungi Candida albicans ATCC 10231 were compared. Results of flavonoid analysis suggested that content of flavones and flavonols in products were uniform and ranged from 0.14% to 0, 41%, but content of flavanones varied greatly from 0.43% to 18.78%. Total flavonoid content, as the sum of two colorimetric methods in propolis, was between 0.78% and 19.20%, and the most products had flavonoids content below 9%. All products with the content of total flavonoids more than 1% showed antimicrobial activity against four Gram-positive bacterial strains tested, and against P. aeruginosa and yeast-like fungi C. albicans. Total flavonoid contents, represented as the sum of two colorimetric methods, could be useful methods for estimation of flavonoid contents products with propolis. Our results indicate that the quality of commercially propolis products does require verification.

propolis; products; flavonoids; antimicrobial colorimetric

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