Chemical variability and antioxidant activities of the essential oils of the aerial parts of Ammoides verticillata and the roots of Carthamus caeruleus and their synergistic effect in combination

Aim and objective: Oxidative stress is implicated in the development and progression of many disease. Some of appropriate actions that could be initiated to taken to resolve the problem of these diseases are search for new antioxidant substances isolated from plants. The aims of this study were to study the intraspecies variations of A. verticillata and C. caeruleus essential oils from 8 locations using statistical analysis, the in vitro antioxidant properties of collective essential oils and in combinations.

Materials and methods: The essential oils were analyzed by GC and GC-MS. The intraspecies variations of the essential oil compositions were discussed using principal component analysis (PCA) and cluster analysis (CA). The antioxidant properties were evaluated DPPH-radical scavenging activity and β-carotene bleaching test.

Results: The main components of Ammoides verticillata collective essential oil (Coll EO) were thymol (30.5%), carvacrol (23.2%), p-cymene (13.1%), limonene (12.5%) and terpinene-4-ol (12.3%). While roots of Carthamus caeruleus essential oil were dominated by carline oxide (86.2%). The chemical variability allowed the discrimination of two main Groups for both Coll EOs. A direct correlation between the altitudes, climate and the chemical compositions was evidenced. Ammoides verticulata and Carthamus caeruleus Coll Eos showed good antioxidant activity. In binary mixture, the interaction both Coll Eos and between oils rich of thymol and/or carvacrol with carlina oxide produced the best synergistic effects, compared to individual essential oils and the synthetic antioxidant (BHT).

Conclusion: Ammoides verticillata and Carthamus caeruleus essential oil blends can be used as a natural food preservative and alternative to chemical antioxidants.

Keywords: Antioxidant activities; Carlina oxide; Carvacrol; Collective essential oils; Synergistic effects; Thymol.