Antimicrobial activity of Centaurea species

The antimicrobial activity of the ethyl acetate, acetone, chloroform, and ethanol extracts from the Centaurca species C ptosomipappoides Wagenitz, C. odyssei Wagenitz, C. ptosomipappa Hayek, C amonicola Hub. Mon, and C. kurdica Reichardt (Compositae) were investigated by agar-well diffusion assay, and all of the extracts exhibited an antimicrobial effect against most of the bacteria and all of the yeasts tested. Although the plants and extracts differed in their activities against the microorganisms tested, the extracts displayed no antifungal activity against the fungi tested. Ethyl acetate extracts showed most significant inhibitory activity, and the yeasts were more suscebtible to the extracts than the bacteria in general. Therefore, minimal inhibitory concentration (MIC) of only ethyl acetate extracts of the samples was determined for some bacteria and the yeasts. In conclusion, C kurdica was the most active antimicrobial plant. Ethyl acetate extract of C odyssei and C kurdica should be further evaluated against human pathogenic yeast isolates, as its antimicrobial activity is stronger than the standard antibiotic ketokonazole.