Chemical composition and antimicrobial activity of the essential oil of the underground parts of Gentiana asclepiadea

Abstract

The aim of this work was to examine the chemical composition and the in vitro antimicrobial activity of the essential oil of Gentiana asclepiadea. G. asclepiadea is a member of the large genus Gentiana in the family Gentianaceae [1]. Gentiana species are distributed in Europe, Asia, North America and South America [2]. The underground parts of several Gentiana species are widely used throughout the world as potent stomachic and hepatoprotective agents, because they contain bitter principles [3]. The essential oil from the underground parts (roots and rhizomes) of Gentiana asclepiadea (Gentianaceae) from Southwest Serbia (locality Stranjani, the mountain Jadovnik) was investigated by GC-MC analyses. One hundred and thirty four components were characterized in the oil. Oxygenated monoterpenes (16.18%) and oxygenated sesquiterpenes (30.15%) were the dominating chemical classes in the sample analyzed. The main constituents were the oxygenated sesquiterpenes caryophyllene oxide (7.56%) and τ-cadinol (5.56%). The inhibitory effect of the essential oil was tested against one fungus and six bacterial species by the macrodilution method. Minimum inhibitory concentration (MIC) was tested in the concentration range of 5.00–0.078µL/mL. The oil showed activity with MIC values ranging from 2.5–5.0µL/mL. The most sensitive microorganisms were Bacillus subtilis, Klebsiella pneumoniae and Staphylococcus aureus (FSB 30) with MIC values of 2.5 L/mL. Micrococcus lysodeikticus and Staphylococcus aureus (ATCC 25923) showed a higher resistance than other microorganisms in test. The commercial antibiotics, amracin (for bacteria) and nystatin (for fungus), showed stronger antimicrobial activity than the essential oil.