## 3 Results and Discussion
### Antioxidant Activity  
Different assays have been developed for the evaluation of the antioxidant activity of plant materials. Among them ORAC assay, that measures the capacity of a sample to neutralize peroxyl \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Extract** & **Yield (\%)** & \
\begin{tabular}{c} **Total Flavonoid Content** \\ **(mg QEs/g Extract)** \\ \end{tabular} &
\begin{tabular}{c} **Total Phenolic Content** \\ **(mg GAs/g Extract)** \\ \end{tabular} \\ \hline Ethyl acetate & 4.29 & 11.67 \(\pm\) 0.03 b & 37.45 \(\pm\) 1.73 a \\ Methanol & 11.26 & 14.76 \(\pm\) 0.21 a & 20.40 \(\pm\) 1.36 b \\ Water & 21.15 & 4.27 \(\pm\) 0.42c & 18.19 \(\pm\) 0.17 b \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Extraction yield, total phenolic and flavonoid content of _Z. taurica_ subsp. _cleanoides_ extracts x.  
radicals, FRAP and TAC methods which take place at low pH and depend on the reducing capacity of the compounds presented in a mixture, DPPH and ABTS assays that measure the overall capacity of a sample, ferrous chelating activity that depends on the chelating capacity of a component. When examining the antioxidant activity of a mixture, it is important not to perform only one antioxidant method in order to evaluate the overall activity. Antioxidant assays present differences in their mechanism of action and limitations as they react differently with the matrix. For example, FRAP assay cannot detect compounds that act by radical quenching [35], and DPPH method is more suitable when lipophilic antioxidant compounds are presented [36]. In our study, ethyl acetate extract showed the best antioxidant activity followed by the extract of methanol. The reducing activity measured with FRAP and CUPRAC assays was found to be better at the methanol and ethyl acetate extracts respectively. This result was expected, taking into account that reducing capacity of an extract is positively correlated to its phenolic content. Regarding the FRAP assay, no statistically significant difference between the activity of methanol (\(1.14\pm 0.06\)) and aqueous (\(1.54\pm 0.15\)) extracts was observed (\(p>0.05\)) (Table 2). For the DPPH and ABTS assays, water and methanol extracts presented lower IC50 values than the ethyl acetate extract. However, our results, did not confirm the study of [PERSON] et al. [37], who observed that non-polar solvents are correlated with better antioxidant activity. Comparing the IC50 values between the two radical scavenging assays for each extract, a notable variation exists. Nonetheless, as it is already mentioned, different chemical properties and polarity of the compounds presented in an extract, can significantly affect its bioactivity [38]. In addition, no statistical difference between the methanolic and aqueous extracts was observed (Table 2). Regarding the chelating activity of Fe\({}_{2}+\), ferrozine and ferrous ion form a stable colored solution. However, the presence of chelating compounds like phenolic compounds interrupts the formation of this stable complex. As a result, decrease in the color of the solution, which corresponds to decreased absorbance measurement occurs. In our study water extract had the best chelating activity, followed by the methanol and ethyl acetate extracts (Table 2). Correlation between the total phenolic content and the antioxidant assays performed, ranged from r = 0.998 and r = 0.807, while the respective correlation regarding the total flavonoid content ranged from r = 0.825 and r = 0.157 (Table S1-Supplementary Material). According to these results, it can be concluded that the antioxidant activity of the extracts may be mostly attributed to the total phenolic content. Total phenolic and flavonoid content of different _Ziziphora_ species, as well as their potential antioxidant activity, is discussed in various studies [39; 40]. [PERSON] and [PERSON] [39] evaluated the bioactivity of _Ziziphora clinopodoides_ from Iran, regarding the antioxidant activity and the total phenolic and flavonoid content.