# GC- and UHPLC-MS Profiles as a Tool to Valorize the Red Alga Asparagopsis armata+
## 3 Results and Discussion
### UHPLC-MS Characterization of A. armata Aqueous Extract  
Given the above discussed, the aqueous extract obtained at room temperature (extract **2**) was analyzed by UHPLC-MS in the negative mode and showed the presence of several phenolic compounds (Figure 2 and Table 3). The most noticeable aspect of the UHPLC-MS profile is the richness in compounds having bromine atoms (Table 3 and Figure 3), aspect that it is not completely new in view of the publications concerning _A. armata_[11; 27] and other red algae [28; 29; 30]. Figure 2: UHPLC chromatogram of _A. armata_ aqueous extract, recorded at 280 nm. Figure 3: (a) Proposed structures for monobromide derivatives; (b) proposed structures for dibromide derivatives; (c) proposed structure for tetrabromide derivative. \begin{table}
\begin{tabular}{l l l l l} \hline
**R (min)** & **UV-Vis (nm)** & **[M-H]- (nm/s)** & **MS\({}^{2}\) (nm/s)** & **Possible Compound** \\ \hline
1.43 & 201, 324 & 333/335 \({}^{\text{a,b}}\) & 302/304, 254, 195, 125 & Methyl 3-(2-bromo-3,4-strihydroxyphenyl)acrylate \\
1.74 & 193, 262, 324 & 353 & 191, 179 & Caffe acid derivative \\
1.86 & 192, 229, 327 & 341 & 179, 135 & Caffe acid derivative \\
3.69 & 195, 232, 285 & 524/526/528 \({}^{\text{c,e}}\) & 473/475/477, 293/41/433, 286/28, 270/272, 255/257, & Methyl 3-(5-bromo-3,4-5-trihydroxyphenyloxy)-2 \\
2.4-hydroxyphenyloxy & 2.4-hydroxyphenyloxy & 2.4-hydroxyphenyloxy & 2.4-hydroxyphenyloxy \\
5.08 & 193, 214 & 586/588/590/592/594 \({}^{\text{d}}\) & 577/574/578/580, 556/558/580, 558/560, 552/564, & Methyl 12-3-dimens-(5-5,4-bromo-3,4- \\  & & & 322/324/326, 306/308/310, 280/282/284, 264/266/268 &dihydroxyphenoxy)-4-hydroxybenzoate \\
12.34 & 195, 232 & 454/456/458/460/462 \({}^{\text{d}}\) & 272/472/472, 262/228/230 & Unknown \\
13.10 & 243, 274 ah & 320/322 \({}^{\text{a,d}}\) & 274/276, 241, 136 & 3-(3-bromo-4,5-dimethoxyphenyloxy)acrylic acid \\
14.51 & 243, 274 ah & 550/552/554 \({}^{\text{c,e}}\) & 505/507/509, 470/472/474, 320/322, 274/276, 242, 191, 24-bromo-3,4-dimethoxy-3,5-methylphenoxy-3-(3-bromo- \\
15.20 & 257, 282 ah & 369 & 163 & 4-(5-dimethoxyphenyloxy)phenylogenic acid \\
18.97 & 249, 2868h & 323 & 163 & \(p\)-Counteracid derivative \\ \hline \end{tabular}
\end{table} 
Table 3: Tentatively identified compounds on _A. mutans_ aqueous extract by UHPLC-MS. Among the identified compounds are four cinnamic acid derivatives, specifically from caffe and _p_-coumaric acids (Table 3), prevalent compounds produced by natural resources, including seaweeds and other marine organisms [31; 32]. The fragments observed in MS2, _m_/z 179, and _m_/z 163 are an essential clue to establish that the compounds are respectively caffe and _p_-coumaric acid derivatives (Table 3). The other metabolites present in the extract are brominated derivatives, and the compound with a retention time of 12.34 min could not be identified, but the isotopic pattern suggests that it has four bromine atoms (Table 3). A structure was proposed for the remaining five metabolites (Figure 3) based on the pseudomolecular ion, isotopic pattern, and fragment ions observed. However, we should highlight that we did not establish the aromatic rings substitution pattern, and in the proposed structures, the substituents order was made considering the most common ones described in the literature [28; 30]. Compounds eluted at 1.43 min and 13.10 min were identified as cinnamic acid derivatives bearing one bromine atom (Figure 3a) due to their pseudomolecular ion isotopic pattern (Table 3). Moreover, brominated polyphenols and polymethoxybenzes are commonly found in seaweeds [30]. The main fragments ions suggest that the compound eluted at 1.43 min is the methyl 3-(2-bromo-3,4,5-trihydroxyphenyl)acrylate or one isomer, being the fragment ion _m_/z 254 obtained through the loss of the bromine atom and the fragment ion _m_/z 195 obtained through an extra loss of CO\({}_{2}\)CH\({}_{3}\).