The objectives of this study were (a) to obtain the essential oils (by hydrodistillation [HD] and microwave-assisted extraction [MAE] methods) to determine the effect of the oil extraction method on the chemical composition, oil yield (%), free radical scavenging activity (IC50), ferric reducing antioxidant power (FRAP) value, and antimicrobial properties of Thymus vulgaris (thyme) and Thymbra spicata (zahter); and (b) to determine the effect of different solvents (methanol [80%] and ethanol [80%]) on extraction by means of the phenolic acid composition, total phenolic content, total flavonoid content, IC50, and FRAP value of thyme and zahter. Gas chromatography-mass spectrometry analysis showed that the amount of thymol (55.35%; 50.53%) and p-cymene (11.2%; 11.79%) was found to be highest in thyme, when using HD and MAE, respectively. However, the highest amounts of carvacrol (68.20%; 66.91%) and γ-terpinene (13.25%; 13.94%) were found in zahter, when using HD and MAE, respectively. Thyme essential oil had higher antioxidant capacity for both HD and MAE in comparison with zahter essential oil. Methanol extracts of both thyme and zahter had higher phenolic composition in comparison with their ethanol extracts. Extracts of both plants did not show any antimicrobial properties. However, essential oils of both thyme and zahter showed antimicrobial activity against chosen bacteria. Highest inhibition zone (radius) was shown against Staphylococcus aureus ATCC 9144 by the essential oils.
Keywords: FRAP; IC50; Microwave extraction; Staphylococcus aureus; disk diffusion; thymol.