## 2 Results and Discussion
### Antioxidant Activity  
The antioxidant activity was assessed using the DPPH assay. The IC\({}_{50}\) (the concentration of the sample required to inhibit 50% of free radicals) values of both EO and hydrolat were 14.031 \(\pm\) 0.012 ug/mL and 232.081 \(\pm\) 3.047 ug/mL, respectively. The IC\({}_{50}\) value of BHT used as a positive control was 11.020 \(\pm\) 0.903 ug/mL. ANOVA analysis showed no significant difference between the IC\({}_{50}\) value of EO and that of BHT (\(p>0.05\)). As shown in Figure 2, the essential oil showed interesting anti-radical activities when compared to BHT. In this sense, hydrolat showed limited antioxidant power when compared to the oil. Essential oils are complex mixtures containing several compounds with different functional groups, different polarities, and different chemical behaviors. This chemical complexity could lead to different results depending on the test used. It is thus fitting that an approach with multiple assays aiming to evaluate the antioxidant potential of hydrolat and essential oils was conducted to validate the results obtained. The results obtained revealed that the total antioxidant capacity of EO and hydrolat were 0.091 \(\pm\) 0.007 and 0.131 \(\pm\) 0.004 mg AAE (ascorbic acid equivalent)/mg, respectively (Figure 3). Many studies have established a strong relationship between the chemical composition of essential oils and their antioxidant activity. The evaluation of interactions between natural antioxidant agents and other food components is an important step in the discussion of total antioxidant power in terms of health benefits. The large diversity of chemicals from a natural source, in addition to their potential interactions and action mode, make it difficult to assess the antioxidant effect by using a simple procedure [31]. It was reported that the antioxidant activity of essential oils was due to their chemical composition, particularly due to compounds with hydroxyl functions [32; 33; 34]. Consequently, essential oils that are higher in terpen exhibit greater antioxidant power [35; 36]. Metal ions are necessary for biochemical and physiological cellular functions, however, sometimes these ions go under wrong processes to cause lipid peroxidation, oxidative stress, or tissue injury in the absence of antioxidant agents [37]. Figure 2: Anti-free radical activity of essential oil and hydrolat from _W. frutscens_. In this study, the antioxidant power was also evaluated using the FRAP method. As shown in Table 2, The IC\({}_{50}\) values of both essential oil and hydrolat were 4.618 \(\pm\) 0.045 \(\mu\)g/mL and 8.997 \(\pm\) 0.147 \(\mu\)g/mL respectively. Therefore, we could confirm that EO possessed strong antioxidant power when compared to hydrolat (_p_ < 0.05). Thus, we can suggest that our EO can be highly effective against free radicals. The degradation of fatty acids is one of the main causes of food spoilage as reported in many works. The inhibition of lipid oxidation is frequently ensured by the intervention of natural food preservatives. In the present research, lipid oxidation was assessed by measuring the inhibitory oxidation of linoleic acid in the presence of \(\beta\)-carotene, which was used as a marker. The results obtained showed that the absorbance of \(\beta\)-carotene gradually decreased in the presence of oils, hydrolat, and BHT. Moreover, the decrease in the negative control absorbance was the most important, followed by the hydrolat, essential oil, and BHT (Figure 4). The variation of \(\beta\)-carotene discoloration rate as a function of time may indicate that essential oils work against the oxidation of linoleic acid. The results obtained in this work showed that the percentage of free radical inhibition of both EO and hydrolat was 74.141 \(\pm\) 1.040% and 40.850 \(\pm\) 0.083%, respectively (Table 2). This activity remained significantly lower than that of BHT used as positive controls.