Quality Characters, Chemical Composition and Biological Activities of Oregano (Origanum spp.) Essential Oils from Central and Southern Argentina

Abstract

The objective of this work is to assess the sensory, chemical, physicochemical profiles and the biological activities of Origanum spp. essential oils from central Argentina (Córdoba province) and new production areas in the southern Argentinian provinces of Rio Negro and Neuquén. Chemical (GC/MS), physicochemical (refractive index, density), sensory profiles (color, aroma) and biological activities (four antioxidants tests, anti-yeast and roundworm lethality assays) of four different oregano essential oils ("Compacto", "Cordobes", "Criollo", and "Mendocino") were determined. Essential oils were characterized by high amounts of trans-sabinene hydrate (17.9 - 27.2%), terpinen-4-ol (6.2 - 11.1%), alpha-terpinene (7-9.8%), thymol (12.1-17.4%) and lower amounts of carvacrol (0.1-3.5%). Oils showed varied tints of yellow (light, mid to dark yellow). Physical/chemical properties of oils showed that these parameters can be used to differentiate these oils. The aroma of the oils was characterized as herbaceous, with medicinal, resinous, minty and coniferous notes. Essential oils from central Argentina ("Mendocino" from Córdoba) showed higher acceptance aroma rates. An antioxidant profile showed that the types from southern provinces were the most active (9.2-10.4, arbitrary scale up to 12) than the same oregano-types from central Argentina. A similar trend was observed for anti-yeast and roundworm lethality assays. These higher biological activities were associated with lower aroma and higher color acceptances. The oils from central Argentina having better aroma profiles can be used for food (flavor) and non-food purposes (fragrances), while the oils from the southern provinces having higher bioactivities can be used as new sources of antioxidants and biocides for pharmaceutical, food (preservation) and veterinary industries. This study used a comprehensive science based approach to increase interest in Argentinian natural products and to contribute to develop trade and quality control standards in support of their commercialization.