*3.1. Chemical Composition of Essential Oils and Free Radical Scavenging*

The chemical composition of the EOs is shown in Table 1. A total of nine and 13 compounds were identified in the PMO and TTO, respectively. Levomenthol was reported to be the predominant compound (36.27%) in PMO followed by Cyclohexanone, 5-methyl-2- (1-methyl ethyl)-, Cyclohexanone, 5-methyl-2-(1-methyl ethyl)-, trans-, and D-Limonene. In TTO, 4-Terpinenol was reported to be the predominant compound (42.56%) followed by Gamma-Terpinene, Alpha-Terpinene and Terpineol.

**Table 1.** Identified volatile compounds of peppermint and tea tree essential oils.


**Compound Rt (min) \* (%)** Gamma.-Terpinene 12.53 10.12 Alpha.-Terpinolene 13.59 3.60 trans-β-Terpineol 15.60 0.49 4-Terpinenol 16.76 42.56 Terpineol 17.23 7.91 γ-Terpineol 17.48 1.43 Caryophyllene 24.90 3.19

**Table 1.** *Cont.*

\* Retention time (RT) (as minutes).

In this study, the free-radical scavenging activity of PMO and TTO were assessed through the DPPH radical scavenging test. The radical scavenging activity was observed in EOs at the concentration of 50 μL mL−<sup>1</sup> for each PMO and TTO. PMO had lower radical scavenging activity (54%) compared to TTO (63.56%).
