Antimicrobial activity of the hypercum perforatum l. plant

Abstract

The goal of this study was to determine the level of antimicrobial activity of ethanolic extract of St. John's wort (H. perforatum L.) toward some phytopathogenic bacteria and fungi. The fungi Fusarium oxysporum (Schlecht) and Penicillium canescens (Sopp) were isolated from fruit which was in a process of deterioration. The antifungal activity of the ethanolic extract with concentration of 5–45 mg/ml in the period of 72 hours, was determined by the method of spore counting (Nauber’s chamber). It was concluded that the sample with 45 mg/ml of ethanolic extract of H. perforatum showed most fungistaticity. When 1·10² spores of fungi were inoculated, the number of spores was decreased to 5 spores for F. oxysporum, and to 15 spores for P. canescens. The bacteria Pseudomonas glycinea and Azotobacter chrococcum showed extreme sensitivity to the presence of 25 mg of the extract of H. perforatum. Bacterial growth was inhibited by 53 %. Higher degree of resistance to the extract of H. perforatum was demonstrated by the bacteria Bacillus subtilis. With 25 mg of extract per disc, an inhibition of 25 % was observed, but with 5 mg extract, an inhibition of 1.8 % was detected. The minimum inhibition concentration of ethanolic extract of H. perforatum depends on the phytopathogenic bacteria type (G+, G–), and varies between 1.25–3.5 mg/ml.