Chemical Composition, Antioxidant Activity, and Multivariate Analysis of Four Moroccan Essential Oils: Mentha piperita, Mentha pulegium, Thymus serpyllum, and Thymus zygis.

Abstract

Background: Food chemical antioxidants have demonstrated protective effects against reactive oxygen species and free radicals, but present in excess, harmful consequences might occur on health. Therefore, replacing these synthetic additives with nontoxic natural antioxidants is crucial. Objective: The current study examined aroma profile, antioxidant activity, and multivariate analysis of Mentha piperita, Mentha pulegium, Thymus serpyllum, and Thymus zygis essential oils from Morocco. Methods: GC-MS analysis was carried out to determine the chemical composition of the four oils, and their antioxidant activity was evaluated with 2,2-diphenyl-1-picrylhydrazyl (DPPH), cation radical (ABTS⁺), hydrogen peroxide scavenging capacity (H₂O₂), ferric reducing antioxidant power (FRAP), and total antioxidant capacity (TAC) methods. Results: Isomintlactone (35.55%), pulegone (74.04%), borneol (37.87%), and borneol (30.99%) were the most abundant compounds of M. piperita, M. pulegium, T. serpyllum, and T. zygis EOs. The antioxidant activity of the four EOs was particularly notable, with an IC₅₀ varying between 3.51 ± 0.22 mg/mL and 0.49 ± 0.08 mg/mL by the DPPH method, 1.02 ± 0.21 mg/mL and 0.4 ± 0.7 mg/mL by the ABTS method, and 0.063 ± 0.01 mg/mL and 0.009 ± 0.008 mg/mL by the H₂O₂ method. For the FRAP technique, the EC₅₀ was between 0.42 ± 0.02 mg/mL and 0.09 ± 0.01 mg/mL. Finally, the equivalent concentration of ascorbic acid ranged between 10.42 ± 0.03 mg AAs/mL for M. piperita and 7.25 ± 0.19 mg AAs/mL for T. serpyllum. As determined by multivariate analysis, antioxidant activities through the DPPH, ABTS, TAC, and FRAP were mainly influenced the major compounds of M. pulegium and M. piperita EOs. However, the H₂O₂ method showed a stronger positive correlation with major compounds of T. zygis EO. Conclusion: The EOs derived from M. piperita, M. pulegium, T. serpyllum, and T. zygis species might be exploited as a natural source for antioxidant activity.