## 4 Chemical Composition
maritium_ showed a slow (long-term) response since it accumulated proline several days after the exposure to saline conditions, followed by a significant increase in the oxygen radical absorbance capacity (ORAC), total phenols and total flavonoids values [52]. Moreover, the optimization of agronomic practices such as the use of brackish water or seawater for irrigation purposes could allow for an increase the bioactive compounds content in commercially grown plants and improve the added value of the final product through the design of functional food products or the incorporation of bioactive compounds in nutraceuticals [96]. The total phenolic and flavonoid contents in the aerial part of sea fennel naturally grown in Spain were up to 8.3 mg GAE (gallic acid equivalents) g\({}^{-1}\) dw (dry weight) and 5.6 mg CE (catechin equivalents) g\({}^{-1}\) dw, respectively [97], while the phenolic (31.7 mg GAE g\({}^{-1}\) dw) and flavonoid (25.61 mg CE g\({}^{-1}\) dw) contents were greater in the leaves of the sea fennel collected in France [2]. Moreover, [PERSON] et al. [2], who tested the hydro-ethanolic extracts of sea fennel leaves, identified eighteen compounds that belong to the groups of hydroxycinnamic acids, flavonoids and flavanols. Chlorogenic acid was the most abundant hydroxycinnamic acid (7.25 mg g\({}^{-1}\) DW), while ruin (1.75 mg g\({}^{-1}\) dw) and crissliol (1.31 mg g\({}^{-1}\) dw) were the main flavonoids detected [2]. In addition, [PERSON] et al. [81]reported that the content of chlorogenic, 1.5-dicaffeoylquinic acid, cryptochlorogenic acid were greater in the leaves compared to that in the stems. Moreover, the same authors suggested that quercetin 3-O-rutinoside was only detected in leaves, while the harvesting season may affect the phenolic compounds content and composition [81]. Similarly, [PERSON] et al. [98] suggested a great variation in the profile of bioactive compounds throughout the growing period, a finding that highlights the importance of the harvesting stage on the quality of the final product. Other compounds that were present in considerable amounts were kaempfer, hyperoside, quercetin and neochlorogenic acid [2]. In contrast, [PERSON] et al. [99] reported rutin and 5-caffeoyl quinic acid as the major compounds in the methanolic extracts of sea fennel leaves. In a recent study by [PERSON] et al. [100], the partitioning of the methanolic extracts of sea fennel aerial parts allowed the identification of eight new flavonoids (various methoxyflavones). Moreover, the aerial parts of sea fennel are a source of fatty acids. [PERSON] et al. [73] observed that the total fatty acids content in leaves ranged between 1.9 and 2.7%. Regarding the fatty acids profile, [PERSON] et al. [101] reported that the most abundant fatty acids were linoleic (C18:2 n6, 45.04-49.46%) and linoleic acid (C18:3 n3, 36.0-38.61%). Similarly, [PERSON] et al. [102] identified linoleic (7.2 mg g\({}^{-1}\) dw) and linoleic acid (6.39 mg g\({}^{-1}\) dw) as the main fatty acids, followed by palmitic acid (3.5 mg g\({}^{-1}\) dw). The leaves of sea fennel are also a good source of amino acids. In a recent study, [PERSON] et al. [99] identified eleven amino acids in the leaves of the species, with leucine, lysine, valine, phenylalanine and threonine being detected in the highest amounts. The chemical structures of the major bioactive compounds are presented in Figure 4.  
Figure 4: Chemical structure of major bioactive compounds contained in the aerial parts of sea fennel: (**A**). chlorogenic acid (C\({}_{16}\)H\({}_{18}\)O\({}_{9}\)), (**B**). kaempfer (C\({}_{15}\)H\({}_{10}\)O\({}_{6}\)), (**C**). leucine (C\({}_{6}\)H\({}_{13}\)NO\({}_{2}\)), (**D**). phenylalanine (C\({}_{9}\)H\({}_{11}\)NO\({}_{2}\)), (**E**). linoleic acid (C\({}_{18}\)H\({}_{32}\)O\({}_{2}\)) and (**F**). linolenic acid or a-linolenic acid (C\({}_{18}\)H\({}_{30}\)O\({}_{2}\)).