Antioxidant activity and chemical composition of essential oils of three aromatic plants from La Rioja province

Abstract

Context: The use of many traditional medicinal plants is often hampered by the absence of a proper biochemical characterization, which is essential to identify the bioactive compounds present in it. The essential oils (EOs) of three native species from the La Rioja province were analyzed: Lippia turbinata Griseb and Lippia integrifolia (Griseb.) Hieron (Verbenaceae), and Clinopodium gilliesii (Benth.) Kuntze (Lamiaceae).

Objective: The aim of this study was to evaluate their EOs antioxidant activity (AA) and their chemical composition.

Materials and methods: EOs were analyzed by gas chromatography-mass spectrometry (GC-MS). To enhance the aqueous solubilization of the EOs, EO–water emulsions were prepared (concentration range of 0.1–6 mg mL⁻¹). AA was determined using ABTS, DPPH, and peroxyl radical scavenging assays, as well as by the β-carotene bleaching test.

Results: Piperitenone oxide was a major constituent in L. turbinata, pulegone and piperitenone oxide in C. gilliesii, and β-caryophyllene in L. integrifolia. Lippia turbinata EO was the most active ABTS and DPPH radical scavenger (SC₅₀ values of 0.40 ± 0.14 and 0.74 ± 0.08 mg mL⁻¹, respectively). Clinopodium gilliesii EO exhibited the highest hydrogen peroxide scavenging activity (SC₂₅ value = 1.52 ± 0.27 mg mL⁻¹). In the β-carotene assay, L. turbinata EO was more effective at inhibiting lipid peroxidation than the other two oils (IC₂₅ value = 0.15 ± 0.04 mg mL⁻¹).

Conclusion: Our results suggest that the AA observed can be justified by the presence of oxygenated monoterpenes, mainly piperitenone oxide. Finally, L. turbinata EO might be used as a safe natural antioxidant and food preservative in the food and cosmetic industries.

• Biological activity
• Clinopodium gilliesii
• Lippia integrifolia
• Lippia turbinata
• piperitenone oxide

Acknowledgements

The authors thank Dr. Guillermo Darbyshire for his help with the design and editing of the manuscript.

Declaration of interest

This work was supported by the Universidad Nacional de Chilecito under Grant FyCT 2012. The authors report that they have no conflicts of interest.