Studies on the antimicrobial activity and chemical composition of the essential oils and alcoholic extracts of Gentiana asclepiadea L.

Abstract

The present paper describes the chemical composition and antimicrobial activity of the essential oils, methanolic and n-butanolic extracts of the Gentiana asclepiadea L., collected in Serbia. The essential oils were obtained from underground parts (root and rhizome) and aerial parts (stem, leaves and flowers) of the plant by hydrodistillation and analyzed by GC and GC-MS. The major compounds in the oil from underground part were caryophyllene oxide (7.32%), β-damascenone (6.98%) and β-ionone (2.79%). The main constituents identified in the aerial part oil of G. asclepiadea were toluene (3.79%), tetradecanoic acid (3.37%), linalool (3.17%) and caryophyllene oxide (2.97%). The antimicrobial activity of the essential oils and plant extracts against several pathogenic bacteria and fungi was studied by minimum inhibitory concentration procedures. Klebsiella pneumoniae was very sensitive against oil from roots with MIC of 0.62 µl/ml, while the oil from aerial part exhibited maximum activity against Micrococcus lysodeikticus and Candida albicans with MIC values of 2.5 µl/ml. The methanolic extract of aerial part showed antimicrobial activities on all microorganisms tested at concentrations ranging from 50 to 1600 µg/ml while the n-butanolic fraction of methanolic extract of underground part was found to be less effective (MIC values: 312.5 to 2500 µg/ml).