## 3 Results and Discussion
### TPC, Antioxidant and Antimicrobial Activity of Licorice Extracts
#### 3.2.1 TPC and Antioxidant Activity
However, it should be noted that extremely high extraction temperature may promote possible degradation of phenolic compounds, or may enhance solvent loss through vaporization [48]. As reported elsewhere, phenolic compounds significantly contribute to the antioxidant activity of plant extracts [49; 50]. It is generally stated that the higher the TPC value, the higher the antioxidant activity. In this work, a positive relationship between the antioxidant activity (evaluated by the DPPH assay) and the TPC content was obtained, considering all licorice UAE extracts produced. Figure 2 shows the linear correlation (R\({}^{2}\) = 0.974) obtained between TPC (mg GAE/g) and TEAC (mmol Trolox/g) values. Regarding the effect of temperature and following the observed tendency in the case of TPC content, for all solvents used, the increase of extraction temperature increased the antioxidant activity of the extract. As mentioned before, the extracts obtained using 50% water were those with the lower TPC values and thus, these extracts are those with the lower antioxidant activity (Figure 2). This result strengthens the hypothesis that the addition of water to the organic solvent enhanced the extraction of polar but non-antioxidant compounds. Figure 2: Correlation between antioxidant activity (mmol Trolox/g) and total phenolic compounds (mg GAE/g) of licorice UAE extracts (Table 3). T = 25 \({}^{\circ}\)C: (\(\blacksquare\)) ethanol, (\(\bullet\)) methanol, (\(\blacktriangle\)) ethanol:water and (\(\blacklozenge\)) methanol:water. T = 50 \({}^{\circ}\)C: (\(\square\)) ethanol, (\(\square\)) methanol, (\(\Delta\)) ethanol:water and (\(\lozenge\)) methanol:water. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **TPC** & **DPPH** & _E. coli_ & _S. aureus_ \\  & **(mg GAE/g)** & **(\(\mu\)mol Trolox/g)** & **IC\({}_{50}\) (mg/mL)** & **IC\({}_{50}\) (mg/mL)** \\ \hline ELe25 & 144.25 \(\pm\) 3.03 \({}^{\mathrm{a}}\) & 447.37 \(\pm\) 1.83 \({}^{\mathrm{a}}\) & \(>\)2.5 & \(>\)2.5 \\ MLe25 & 104.05 \(\pm\) 0.22 \({}^{\mathrm{a,b}}\) & 210.77 \(\pm\) 0.17 \({}^{\mathrm{a,b}}\) & \(>\)2.5 & \(>\)2.5 \\ EWLe25 & 80.36 \(\pm\) 3.67 \({}^{\mathrm{b}}\) & 86.92 \(\pm\) 0.99 \({}^{\mathrm{b}}\) & 1.21 \(\pm\) 0.03\({}^{\mathrm{b}}\) & 1.38 \(\pm\) 0.11 \({}^{\mathrm{a}}\) \\ MWLe25 & 59.09 \(\pm\) 5.40 \({}^{\mathrm{b}}\) & 68.01 \(\pm\) 1.26 \({}^{\mathrm{b}}\) & 1.09 \(\pm\) 0.10\({}^{\mathrm{ab}}\) & 1.56 \(\pm\) 0.06 \({}^{\mathrm{c}}\) \\ ELe50 & 162.20 \(\pm\) 1.30 \({}^{\mathrm{a}}\) & 546.52 \(\pm\) 2.16 \({}^{\mathrm{a}}\) & \(>\)2.5 & \(>\)2.5 \\ MLe50 & 126.20 \(\pm\) 2.88 \({}^{\mathrm{a,b}}\) & 277.50 \(\pm\) 0.24 \({}^{\mathrm{ab}}\) & \(>\) 2.5 & \(>\)2.5 \\ EWLe50 & 85.71 \(\pm\) 3.07 \({}^{\mathrm{b}}\) & 102.52 \(\pm\) 0.49 \({}^{\mathrm{b}}\) & 0.84 \(\pm\) 0.04\({}^{\mathrm{b}}\) & 1.43 \(\pm\) 0.06 \({}^{\mathrm{d}}\) \\ MWLe50 & 79.14 \(\pm\) 2.16 \({}^{\mathrm{a,b}}\) & 62.18 \(\pm\) 1.28 \({}^{\mathrm{b}}\) & 0.97 \(\pm\) 0.03\({}^{\mathrm{b}}\) & 1.93 \(\pm\) 0.01 \({}^{\mathrm{b}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Total phenolic compounds (TPC), antioxidant activity (DPPH free radicals scavenging assay expressed as TEAC value) and antimicrobial activity (IC\({}_{50}\) mg/mL) of licorice UAE extracts. Among the identified and quantified licorice bioactive compounds, only in the case of glabridin, the less polar identified polyphenol, did an increase of its concentration show a positive effect on the antioxidant activity of the extract.