Abstract

Hypericum scabrum L. is one of the herbal and perennial medicinal plants belonging to Hypericaceae which all of its floral on aerial part has extensive use in preparing traditional medicines. The major constitutes of H. scabrum are α-pinen, thymol and carvacrol. The study was conducted to determine variations of antibacterial activity, thymol and carvacrol content in different populations of H. scabrum flowers. The antibacterial activity was tested by agar disc diffusion and serial dilution assays against four pathogens (Staphylococcusareus, Pseudomonas aeroginosa, Basilluc cerus and Esherishia coli). The extract was characterized using high-performance liquid chromatography (HPLC). The contents of thymol and carvacrol, varied 0.93 to 1.30 and 0.25 to 0.39 mg/g extract, respectively. The highest content of thymol and carvacrol in all investigated samples was obtained from Sheyda and Lordegan population, respectively. The inhibition zones and MIC values for bacterial strains, which were sensitive to the extract of H. scabrum L., were in the range of 8 to 19 mm and 0.019 to 5000 mg/ml, respectively. The populations of Sheyda and Lordegan showed the strongest antibacterial activity.

Key words: Hypericum scabrum L., population, antibacterial activity, thymol, carvacrol.