Chemical composition of essential oils and in vitro antioxidant properties of extracts and essential oils of Calamintha origanifolia and Micromeria myrtifolia, two Lamiaceae from the Lebanon flora

There is a growing interest of industry to replace synthetic chemicals by natural products with bioactive properties from plant origin. The aim of this study was to determine the chemical composition of essential oils of Calamintha origanifolia (Labill.) Boiss and Micromeria myrtifolia Boiss., two Lamiaceae species collected in Lebanon, and to characterize the in vitro antioxidant activities of their extracts and of the essential oils. The essential oils from aerial parts of the two plants were isolated by hydrodistillation technique using a Clevenger-type apparatus. The extracts were prepared with three solvents of different polarity (n-hexane, chloroform and methanol). A total of 97 constituents were identified in M. myrtifolia and C. origanifolia oils using GC/MS; the main components detected were β-caryophyllene together with caryophyllene oxide and hexadecanoic acid in M. myrtifolia while isomenthone, menthone, pulegone and α-bisabolol were the main compounds in C. origanifolia. The methanol extracts of both species exhibited the highest phenol content and were found to be significantly more active than chloroform and hexane extracts when assayed by DPPḢ radical scavenging and ferric ion reduction (FRAP) assays. The results of this study provide a clear picture of the volatiles of M. myrtifolia and C. origanifolia and demonstrate that these plant species have an huge potential as an alternative to chemical additives for the food industry due to their antioxidant properties.