Antimicrobial activity of some plant materials used in Armenian traditional medicine

Antibiotic resistance has become one of the major problems facing humanity. The need for new antimicrobials has been increased dramatically. Plants are considered as one of the most promising sources for new antimicrobials discovery. Despite relatively small area, Armenia has large diversity of flora with many endemic species. In Armenian folk medicine plant materials have been used to treat various microbial diseases since ancient times. The goal of our research was to evaluate antimicrobial efficiency of different parts of five wild plants species which are commonly used in Armenian traditional medicine.

Plant crude extracts were obtained with maceration technique using five solvents separately: distilled water, methanol, chloroform, acetone, and hexane. Agar well diffusion assay was used for initial evaluation of antimicrobial properties of plant materials against five bacterial and two yeast strains. Minimum inhibitory concentrations of the most active plant parts were determined by broth microdilution method.

Crude extracts of all five tested plants expressed antimicrobial activity against at least four test strains at 500 μg ml^-1 concentration. Minimum inhibitory and bactericidal/fungicidal concentrations of selected plant parts were determined. Crude acetone and hexane extracts of Hypericum alpestre and acetone extract of Sanguisorba officinalis inhibited the growth of P. aeruginosa even at 64 μg ml^-1 concentration. Chloroform and acetone extracts of Sanguisorba officinalis exhibited cidal activity against P. aeruginosa till 256 μg ml^-1. Acetone was the most effective solvent for solubilizing antimicrobial compounds for almost all tested plant materials.

Thus, antimicrobial activity of some medicinal plants used in Armenian traditional medicine was evaluated. Some of the plants had rather low minimum bacteriostatic/bactericidal concentrations and therefore they have prospective for further more inclusive studies.