## 6 Characterization, Identification, and Purification of MAAs
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Species** & **Type of MAAs** & **Extraction** & **HPLC Methodology** & **Furification** & **Identification** & **Ref.** \\ \hline \multirow{4}{*}{_Pyregi columna_} & \multirow{4}{*}{M-gly: SH, P-334, Pi, A-330} & - Extraction in water:methanol & \multicolumn{1}{c}{: Sphereclone CS column (5 \(\mu\)m,} & \\  & & (802.0) (2 h, 45\({}^{\circ}\)C): Redisolve & \multicolumn{1}{c}{: Element: 25\(\times\) methanol + 0.1\(\times\) acetic} & \multirow{4}{*}{NO} & [77] \\  & & & in methanol & acid in water & & \\  & & & & - Isocratic flow (0.5 mL min\({}^{-1}\)) & & \\ \hline \multirow{4}{*}{_Causpriches corness_} & \multirow{4}{*}{SH, P-334} & - Extraction in water:methanol & \multicolumn{1}{c}{: LicCrow dP 18 column (5 \(\mu\)m,} & \\  & & (802.0) (2.5 h, 45\({}^{\circ}\)C) & \multicolumn{1}{c}{: Element: 0.2\(\times\) acetic acid in water} & \multirow{4}{*}{NO} & [130] \\  & & - Redisolove in methanol & \multicolumn{1}{c}{: Isocratic flow (1 mL min\({}^{-1}\))} & & \\ \hline \multirow{4}{*}{_Chontras cispus_} & \multirow{4}{*}{Pi, SH, PL, Pe} & - Extraction in water:methanol & \multicolumn{1}{c}{: Spherelock RP 5 column (5 \(\mu\)m,} & \\  & & (75.25) (2 h, 45\({}^{\circ}\)C) & \multicolumn{1}{c}{: Element: 25\(\times\) unit + 0.1\(\times\) acetic acid} & \multirow{4}{*}{NO} & [131] \\  & & - Redisolove in methanol & \multicolumn{1}{c}{: In water} & \\  & & - Isocratic flow (0.7 mL min\({}^{-1}\)) & & & \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._Chromatography is a general analytical technique used to separate a mixture into its individual components. In relation to the MAA purification process, there are different approaches depending on the chemical characteristics and the aim. In the case of its use for cosmeceutical products, the ideal is an extraction and purification free of hazardous solvents for the environment and health, which increases the biocompatibility and safety of the final product. However, to date, very few methodologies use green solvents for the identification and purification of MAAs. This indicates an opportunity to explore new methodologies and techniques for the identification and purification of these molecules with green solvents [121; 132; 133; 134]. It is important to note that there are different criteria and legislations for the selection of green solvents, for which some solvents, such as alcohols of methanol or propanol type, are allowed in low amounts depending on the legislation (e.g., European Chemicals Agency, ECHA). In recent decades, different authors have attempted to purify MAAs. The different strategies vary from simple columns of a resin that are not automated to highly complex systems as UHPLC coupled to a fraction-collection device or liquid-liquid chromatography. Torres et al. [128] purified the MAA porphya-334 using a silica gel column. A methanolic extraction was chromatographed on a silica gel column using a gradient of ethanol and methanol as eluent. De la Coba et al. [127] isolated porphya-334, shinorine, asterine-330, and polythine using adsorption and ionic exchange chromatography. First, the MAA extractions were blended with activated charcoal (adsorption) and eluted with methanol:water (1:1). The fraction obtained was dried, re-dissolved in distilled water, and passed through a Dowex 50 W-X8 (H\({}^{+}\) form; 50-100 um mesh) ion exchange column. To separate porphya-334 and shinorine, distilled water was used as eluent, whereas to separate asterina-330 and polythine, the authors used a gradient of distilled water and 0.35 M HCl. Roullier et al. [135] isolated mycosporine-serinol using centrifugal partition chromatography (CPC). A system composed of n-butanol, acetic acid, and water (4:1:5, \(v/v/v\)) was used. Ryu et al. [123] also purified the MAA porphyrina-344. An aqueous-methanolic extract (water:methanol; 4:1) was dried, redissolved in ultrap water, and transferred to a separating funnel containing chloroform-methanol-ultrapure water.