Abstract

CHANGES IN THE CONTENT OF PHENOLIC COMPOUNDS IN COTINUS COGGYGRIA SCOP. LEAVES COLLECTED IN DIFFERENT MONTHS AND ANTIMICROBIAL ACTIVITY OF EXTRACTS THEREOF

Galina Dimova, Debora Sabotinova, Yoana Rosenova* and Iliya Zhelev

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Abstract

The variation among the main classes of phenolic compounds in smoke tree leaves harvested from two localities, during one growing season, was investigated. A large amount of active components, especially tannins, was determined in the middle of the summer – in July from both analysed locations (14.82 ± 0.22% and 16.30 ± 0.25%, respectively). Other phenols were found in lower concentrations. The maximum amount of flavonoids was at the beginning of plant development – in May (7.67 ± 0.10%) and at the end of it – in August, was the highest amount of phenolic acids (2.78 ± 0.02%). Another interesting result emerged from the comparison of phenol content, both in leaf petioles and twig stems, which, as expected, demonstrated lower constituent values. Two types of leaf extracts (methanol and ethanol) were also tested against Gram-negative and Gram-positive microorganisms. The ethanol extracts displayed some antimicrobial potential against Escherichia coli, Pseudomonas aeruginosa, but showed lower efficacy against Salmonella entericа and Klebsiella. The highest sensitivity to the methanol extract of smoke tree was exhibited by Salmonella enterica, Staphylococcus аureus and Listeria monocytogenes.

Keywords: Cotinus coggygria, Total phenols, Spectrophotometry, Antimicrobial activity.