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

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.