Basic Science

Abstract

In recent years, the consumption of Hypericum perforatum-derived products has increased dramatically and presently it is one of the most consumed medical plants over the word. Hypericum perforatum has a wide range of medicinal applications, including skin wounds, eczema, burns, diseases of alimentary tract and physiological disorders. Beneficial propertis of H. perforatum to human health are related to the high content in phenolic compounds. Phenolic compounds are widely distributed in the plant kingdom, the content of which varies between different species and cultivars, and with maturity, season, region, and yield. Phenols play a major role in the plant. They may protect the plant against biotic or abiotic stresses, and they are also deserving for antioxidant and antimicrobial activity of plant. Phenols are classfied according to their structure as phenolic acid, flavonoids and tannins. Hypericum perforatum extracts contain many types of phenolic derivates (hypericin, hyperforin and their derivates, rutin, hyperozide, quercetin, quercitrin, isoquercitrin, caffeic and chlorogenic acid). Hypericin showed antibacterial, antiviral and anti-inflammatory activity. This study represents the antimicrobial activity of phenolic compounds from three different extracts of H. perforatum against pathogenic bacteria. The aerial parts of H. perforatum were collected in the surroundings of Kragujevac, Serbia, in July 2006 and determined in the Department of Biology, Faculty of Science in Belgrade (No.0799HP). The phenolic compounds were extracted with the following solvents: acetone, ethanol and petrol-ether. The content of total phenol (4.40-12.60 mg/g of plant), flavonoids (4.15-11.85 mg/g of plant) and non-flavonoids (0.25-1.45 mg/g of plant) in samples of the H. perforatum extracts was determined using colorimetric method, with Folin-Ciocalteu reagent. The phenolic compounds were expressed as catechin equivalents. The antimicrobial activity of plant extracts was evaluated using disc-diffusion and macro-dilution assay. The highest inhibitory effect of three extracts of H. perforatum was observed in acetone extract, which contain a high amount of phenolic compounds. The acetone extract showed the better antibacterial activity on all tested bacteria than ethanol and petrol-ether. The most sensitive bacteria was Enterobacter cloaceae. Two bacterial strains Proteus sp. and Pseudomonas aeruginosa showed resistance on all three extracts. The results obtained demonstrate a direct relationship between the phenolic content of the extracts and the antimicriobial activity.