Turkish Journal of Biology




The antibacterial activity of an ethanolic extract of Hypericum perforatum L. was investigated against 8 Gram-negative bacteria (Pseudomonas fluorescens, Pseudomonas phaseolicola, Pseudomonas glycinea, Erwinia carotovora, Enterobacter cloacae, Klebsiella pneumoniae, Agrobacterium tumefaciens, Azotobacter chrococcum) and 2 Gram-positive bacteria (Bacillus mycoides, Bacillus subtilis) by the disc-diffusion and broth tube dilution methods. Ethanol was used for extraction of the plant. The species Pseudomonas glycinea and Azotobacter chrococcum showed extreme sensitivity to the extract of H. perforatum, while no effect was observed on bacteria Klebsiella pneumoniae. Minimum inhibitory concentration (MIC) of the ethanolic extract varied between 1.25 and 3.5 mg/ml. The antifungal activity of the H. perforatum extract at concentrations of 5-45 mg/ml was determined by the method of spore counting; a concentration of 45 mg/ml showed the greatest fungistatic activity. In the case of inoculation of 1 x 10^2 spores of fungi, the number of spores was decreased: with Fusarium oxysporum, only 5 spores were identified, and with Penicillium canescens, 15 spores.


Hypericum perforatum, antibacterial activity, antifungal activity

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