Chemical composition and biological activity of Gaultheria procumbens L. essential oil

Abstract

The aim of this study was to examine chemical composition and biological activity of Gaultheria procumbens L essential oil (EO) against food spoilage and oral microorganisms. The components of EO were identified by GC-MS. Antimicrobial activity was determined against food spoilage (five bacteria and six fungal species) and oral microorganisms (eight bacteria and thirty two fungal species) by microdilution and microplate biofilm assay, antioxidant activity was tested using the persistent free radical 2,2-diphenyl-1-picryl hydrazyl (DPPH), while antiradical activity was examined by fluorescence spectroscopy and electron paramagnetic resonance spectroscopy (EPR). GC-MS analysis showed that methyl salicylate (96.90%) was the main component of the oil. Essential oil inhibited the growth of all microorganisms tested, i.e. food and oral bacteria and fungi, respectively (MIC 0.18-3.00 mg/ml and MBC 1.25-4.00 mg/ml; MIC 0.73-5.00 mg/ml and MFC 2.92-26.67 mg/ml); The oil effectively inhibited the biofilm formation of oral Streptococcus mutans and Candida albicans as well (MIC 25.00 MBC 50.00 mg/ml; MIC 12.50, MFC 50.00 mg/ml). In addition, oil exhibited a dose-dependent DPPH-radical-scavenging activity with IC50 value of 30.61 mg/ml. The specific fluorescence probe 2-[6-(4'-amino)phenoxy-3H-xanten-3-on-9-yl] benzoic acid (APP) and the the spin trap 5-(Diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO), capable for simultaneous detection of different free radical specie were used in antiradical activity of the oil measurements. Oil showed a moderate antiradical activity, reducing quantity of produced hydroxyl radicals to about 20% of initial value. This study succeeds in creating directly comparable and quantitative data for the oil unsufficiently examined so far.