## 2 Characterization and Types of Phenolic Compounds
### Mycosporine-like Amino Acid  
Various marine algal species such as _Asparagopsis armata_, _Chondrus crispus, Mastocarpus stellatus_, _Palmaria palmata_, _Gelidium_ sp., _Pyropia_ sp. (formerly known as _Porphyra_ sp. ), _Gracilaria cornea_, _Soleria chordalis_, _Grateolupia lanccola_, and _Curdiae racovitzae_ (Rhodophyta) have been investigated for this exclusive class of phenolic compounds. This class of compounds is more commonly found free in the intracellular space and around cell organelles sensitive to ultraviolet rays. Mycosporine-like amino acids (MAAs) are formed by cyclo-hexenone or cycloheximide chromophore conjugated to imino alcohol or an amino acid residue [141; 142]. Various MAAs (palything, shinoring, asterina-330, Porphyna-334, palythinol, and usujrene) have already been studied that have high antioxidant, photoproduction, and anti-proliferative (HeLa cancer cell line, human cervical adenocarcinoma cell line) and HaCat (human immortalized keratinocyte) activity [143; 144]. Recent studies have reported other important activities such as anti-inflammatory, and photoprotective activities (an alternative to the synthetic UV-R filters in sunscreens). Thus, MAAs seems to be a special focus on a specific area and application that can be applied to humans. Based on the literature, the different types of marine algae-derived phenolic compounds and their skin cosmetic benefits are tabulated in the below Table 1. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Name of Marine Algae** & \multicolumn{2}{c}{**Searowed-Based Bioactive Compounds**} & **Cosmetic Properties/Benefits** & **References** \\ \hline \multirow{4}{*}{1} & & Catechins, Flavanols, Flavanol & \multirow{4}{*}{Matrix Metalloproteininase (MMP)} & \multirow{4}{*}{[145; 146; 147]} \\  & & glycosides, Gallic acid, Epicatechin, & & \\  & & Phloroglucinol, Pyro catechol, & & \\  & & Gallate, Flavanoids, Anthocyanins, & collagen degradation & \\  & & Stilbenes, Lignans & & \\
2 & _Corallina piluliifera_ (R) & - & & \\
3 & _Sargassum lomeri_ (B) & Sargachromanol E & & \\
4 & _Phycosolarilia vietnamensis_ (R) & Mycosporine-like amino acids (MAAs) & & \\
5 & _Ecklonia carus_ (B) & Phlorotannins & & \\
6 & Macroalgal species & - & & \\
7 & Macroalgal species & Phlorotannins & & \\
8 & _Sargassum fusiforme_ & & & \\  & (as _Hizkia fusiformis_) (B) & Phlorotannins & & \\
9 & _Corallina piluliifera_ (R) & Phlorotannins, Eckol, Fucols, & & \\  & & Fucophorethols, Fuhalds, & & \\  & & Phlorotnids & & \\
10 & Macroalgal species & Phlorotannins & & \\
11 & _Ecklonia carus_ (B) & Phlorotannins & & \\
12 & _Ecklonia carus_ (B) & Phlorotannins such as & & \\  & & ecsktolanol, dieckol & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Applications of marine macroalgae-derived phenolic compounds in skin benefits. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No. ** & **Name of Marine Algae** & \begin{tabular}{c} **S seaweed-Based Bioactive** \\ **Compounds** \\ \end{tabular}  & **Cosmetic Properties/Benefits** & **References** \\ \hline
13 & Brown algae species & \begin{tabular}{c} Phlorotannins such as Phloroeckol, \\ Tetrameric chloroglucinol \\ \end{tabular}  & Anti-skin aging, Antioxidant & [165] \\
14 & _Corallina pihilifera_ (R) & Phlorotannins & Metalloproteininase inhibitors, and UV \\  & & & protectors, Prevent collagen & [166] \\  & _Ulta clathrata_, _Ulta compressa_ (as \\  & _Entemporonia compressa_, _Ulta_ & & degradation, Wrinkle formation \\
15 & _intestinalis_, _Ulta lirae_, _Ulta lirae_, _Ulta australis_, _Capssophinen fulivensens_, _Cluatororpha moniligeru_ (G) & Bromophenols, Flavonoids & Highly radical scavenger & [167, 168] \\
16 & _E. cara_ (B) & Phlorotannins & UVB protector & [169] \\  & _Sacchiura japonica_ & & Utilized in facial masks, UV & [170, 171, 172] \\
17 & (as _Laminaria japonica_), _Eckolina caroa_, (B) & & \begin{tabular}{c} Phlorotannins \\ _Ulta compressa_ \\ \end{tabular}  & \begin{tabular}{c} Antioxidant effect, Anti-aging \\ _Tyrosinase inhibitor_, \\ Melanin Inhibition \\ \end{tabular}  & \