Phytochemical composition and antimicrobial activities of the essential oils from summer savory (Satureja hortensis L.) growing in shading condition

This study was conducted to investigate the effect of plant shading (covered by pearl shade nets with a 40% shade index or nonshading plants from open field) on the content and composition of essential oils extracted from summer savory (Satureja hortensis L.) during the flowering stage cultivated under the ecological conditions of Serbia. The summer savory essential oil (SSEO) was extracted by Clevenger hydrodistillation. According to the GC/MS analysis of the SSEO, twenty-five and twenty-six components were detected in the non-shaded and shaded plants, respectively. The yield of SSEO from non-shaded plants was 1.64%, while SSEO from plants covered by shade nets was 1.76%. Carvracol (48.7-53.25%) and gamma-terpinene (32.7%-36.8%) were found to be the main components in SSEO, followed by p-cymene (3.4%-3.2%), alpha-terpinene (2.9%-3.5%) and limonene (1.9-1.3%). In the DPPH assay, SSEO showed an IC50 of 0.99 mu g mL(-1) in shaded and an IC50 of 1.01 mu g mL(-1) in non-shaded plants. Additionally, SSEO exhibited strong antibacterial activity against Escherichia coli (44.3-48 mm inhibition zone), Bacillus subtilis (34.7-41.0 mm), Klebsiella pneumoniae (28.3-29.0 mm) and Proteus vulgaris (21.0-24.3 mm). A possible practical application of this study would be to grow summer savory at higher plant densities, or as an intercrop, because it does not require too much light for production.