## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Extraction Conditions**} & **Solid** & **Phe** & **Fla** & **Anth** & **Tan** & **DPPH** \\ \cline{2-8}  & **Yield \%** & & & **mg/g dw\({}^{(a)}\)** & & **\%** & **Reference** \\ \hline \multicolumn{8}{c}{Ultrasound assisted extraction} \\ \hline - & 500 mg, 50 mL (ratio 1:10), Ethanol-water & — & 6.90 & 4.05 & 17.53 & — & — & [35] \\ - & 802.00, 30 \({}^{\circ}\)C, 20 min & — & — & 52.94 & — & — & [36] \\ - & Red dried calves 1.5 g, solid: liquid ratio & — & — & — & 5.66 & — & — & [37] \\ 230 g/L, ethanol-water (26.1–41.7) \% (\%(\%)), & & & & & & & \\ 426.9 W, 20 kHz, 45 min & — & — & 5.00 & — & & & \\ - & Roselle dried calyx, solid-liquid ratio 1:25 & — & — & — & 5.66 & — & — & [37] \\ (g/mL), Temperature 50 \({}^{\circ}\)C, time 22.5–45 & & & & & & & \\ \hline \multicolumn{8}{c}{Solid- Liquid Extraction} \\ \hline - & 20 g, 250 mL ethanol, 72 h. & 12.8 & 27.6 & 33.8 & — & — & 69.00 & [33] \\ - & 2.5 Red Purple, dry calves, 25 mL. & — & 26.49 & — & 2.21 & — & — & [38] \\ Ethanol: water solutions (50:50 and 70:30 \%, \(\gamma\)/g), 2 h. & & & & & & & \\ - & 2.5 g light red dry calves, 100 mL water, & — & 15.5 & — & 4.52 & 0.43 & 65.00 & [34] \\ boiled 15 min & — & 36.50 & — & 10.99 & 1.04 & 85.00 & [34] \\ - & 2.5 g white dry calves (“Alma Blanca”), & — & 13.5 & — & 0.20 & 0.24 & 65.00 & [34] \\ 100 mL water, boiled 15 min & & & & & & & \\ \hline \hline \multicolumn{8}{c}{Phe-Phenols; Fla-Flavonoids; Anth=Anthocyanin; Tan=Tannins; (*) Phenols (mg GAE/g dw); Flavonoids (mg QE/g dw); Anthocyanin (mg Cya3 GE/g dw); Tannins (mg QUE/g dw).} \\ \end{tabular}
\end{table} 
Table 2: Phytochemicals in calyx of Roselle (_H. sabdariffa_) extracted with ultrasound assisted and solid-liquid methods. Table 2 shows multiple reports of works on _H. sabdariffa_. The concentration of the polyphenols (13.02 mg GAE/g dw) and flavonoids (4.981 mg CE/g dw) of the red variety determined in this study are higher than the 6.90 mg GAE/g dw and 4.05 mg QUE/g obtained with 20 min of sonication [35], and lower than 27.6 mg GAE/g polyphenols and 33.8 mg QUE/g flavonoids obtained with ethanol in a S-L process [33]. Anthocyanin of this work of the red variety (1.855 mg Cya3 GE)/g dw) are lower than most of the data in Table 2, except the 2.21 mg Cya3 GE/g dw obtained from red purple dry calves [38]. Also, tannins of this work for red variety (0.745 mg CE/g dw) are higher than the 0.43 QUE/g dw extracted from light red variety [34], but lower than the 1.04 mg QUE/g dw from dark red calves [34]. Regarding white calves, a slightly lower yield was obtained in phenols (12.953 GAE/g dw), and lower in anthocyanins (0.005 mg Cya3 GE/g dw) and tannins (0.049 mg CE/g dw), compared to those obtained from white variety calices with boiling water of 13.5 mg GAE/g, 0.20 mg Cya3 GE/g and 0.24 mg QUE/g, respectively [34]. Respect to free radical scavenging activity by DPPH, similar values were obtained to those found by other researchers: 69% for red calyx [33] ; 25-85% for dark red dry calyces and 20-65% for light red white calyx, aqueous extracts, concentrations of 50-250 ug/mL [34]; 5.60, 10.24, 17.44 and 31.28% with polyphenol content of 669.48 and 5012.54 mg GAE/100 g at concentrations of 625, 1250, 2500 and 5000 ug/mL, respectively [39]. In addition, scavenging activities of 2, 11, 23, 53 and 86% for an extract with phenolic content of 41.07 mg GAE/g at concentration of 5, 10, 50, 125 and 250 ug/mL, respectively [40]. The antioxidant activity of extracts depends on the amount and type of polyphenols it contains, with positive correlation between phenolic content and antioxidant activity [41]. Many and diverse compounds have been identified in Roselle with biological properties. It has been noted that flavonoids are the main antioxidant group [42]. Quercetin, myricetin and proanthocyanidins, of the epigallocatechin and epigallocatechin-gallate type catechin, are flavonoids found in _H. sabdariffa_[43].