# GC- and UHPLC-MS Profiles as a Tool to Valorize the Red Alga Asparagopsis armata+
## 3 Results and Discussion
### GC-MS of Lipophilic Extract
The peaks at 19.1 and 19.3 min also correspond to two unsaturated alcohols silylated, but in this case mono-brominated, as deduced from the isotopic pattern analysis of fragments [M-15]\({}^{+}\) at _m/z_ 333/335 (1:1); [C\({}_{2}\)H\({}_{6}\)SiBr]\({}^{+}\) at _m/z_ 137/139 (1:1). The peak at _m/z_ 179 on the mass spectra of both isomers, corresponding to the non-brominated fragment [C\({}_{13}\)H\({}_{23}\)]\({}^{+}\) ([M-90-Br]\({}^{+}\)), suggests the same bromine substitution pattern on both isomers. The molecular formula of the two compounds on the extract is C\({}_{13}\)H\({}_{25}\)BrO, named bromotridecenol. The difference between them should be the position of the double bond, difficult to determine by MS. The second most abundant halogenated compound (7.8%) corresponds to the peak at 8.5 min, identified as 3-bromoprop-2-enoic acid TMS derivative. The mass spectrum shows the signals at _m/z_ 207/209 (-1:1), corresponding to the fragment C\({}_{5}\)H\({}_{8}\)BrO\({}_{2}\)Si\({}^{+}\) ([M-15]\({}^{+}\)) and 137/139 (-1:1) corresponding to [(CH\({}_{3}\))\({}_{2}\)SiBr]\({}^{+}\), both mono-bromine silylated fragments typical from halocarboxylic acids pattern fragmentation [33]. The _m/z_ value of these two fragments differs by 2 units from those observed for 3-bromopropanoic acid, evidencing the existence of a double bond at C2-C3. Moreover, the three signals observed in the spectrum of 3-bromoprop-2-enoic acid TMS derivative at _m/z_ 143 [M-Br]\({}^{+}\), 75 (base peak, [HOSi(CH\({}_{3}\))\({}_{2}\)]\({}^{+}\)) and 53 (loss of trimethylsilanol and HBr resulting the fragments [C\({}_{3}\)H\({}_{3}\)O]\({}^{+}\)), all corresponding to non-brominate fragments, confirm the proposed identification of compound at 8.5 min. This compound was previously identified on the _A. armata_ as ethyl ester [14]. The presence of halogenated alcohols and carboxylic acids in _Asparagopsis_ species was already reported in the literature [11, 14, 34]. The results of several studies show that these are toxic metabolites that, in addition to exhibiting antimicrobial activity, confer a competitive advantage over predators and other species [35, 36]. Moreover, to our best knowledge, this is the first time that 1,4-dibromobuten-1-ol and its isomer have been reported and quantified in the _Asparagopsis_ genus. The second most abundant family of compounds was the fatty acids (35.8%), being the content of saturated acids 5.1 times higher than the content of unsaturated acids (Figure 4). This can be an asset since saturated fatty acids seem to have a beneficial effect on the modulation of the immune system on food-borne bacterial infection [37]. The results of Table 4 show that the second most abundant compound is palmitic acid (20.3%), being the most plentiful fatty acid (57.0%). In comparison, the second most abundant fatty acid is myristic acid (16.1%). These results are in line with those published by [PERSON] et al. [38] for the same species, where palmitic and myristic acids are, by far, the most abundant fatty acids. Interestingly, in line with this result, the monoacylglycerols of these two acids, monomyristin and monopalmitin, were identified and quantified in the extract (Table 4; \(\mathrm{Rt}=41.5\) and \(\mathrm{Rt}=43.3\) min, respectively), representing about 2.1% of the compounds detected. As far as unsaturated fatty acids are concerned (Figure 4), the most abundant is oleic acid ((9Z) 9-octadecenoic acid). It is the third most abundant fatty acid (9.83%), representing only 3.50% of the identified compounds. From the point of view of beneficial effects on health, the presence of oleic acid can be considered an asset, while the high content of palmitic acid can be seen as an obstacle to seaweed consumption. However, we draw readers' attention to the fact that data in the literature suggest that the potential adverse effect of saturated acids is controversial and should be reviewed [39, 40]. Moreover, the results show that _A. armata_ can be valued as a source of palmitic acid.