## 4 Phenolic Compounds  
Phenols are a diverse group of phytochemicals which include phenolic acids (hydroxybenzoic acids and hydroxycinnamic acids) and flavonoids, amongst other types of compounds [32]. They are potent antioxidants linked to various health benefits, such as anti-inflammatory, anti-obesity, and even anti-cancer properties [11, 46]. They have also been shown to prevent cardiovascular diseases and diabetes [46]. Phenolic compounds can be extracted with water, polar organic solvents, and their mixtures [46]. The colourimetric Folin\(-\)Ciocalteu method is well established and commonly used to estimate total phenols in plant extracts. In this method, gallic acid is used to determine a reference curve, and total phenols are measured as an amount of gallic acid equivalent (GAE) in the dried extract. The protocols use Folin\(-\)Ciocalteu reagent to measure absorbance at 760 nm, and the process is well described by [PERSON] [47] and [PERSON] et al. [48]. The total phenols found in halophyte extract are summarised in Table 2. The concentration of phenols may vary between different parts of a plant, and [PERSON] et al. [35] and [PERSON] et al. [40] have shown that phenol content is highest in extracts obtained from flowers. The concentration of phenolic compounds depends on biological factors, such as genotype, the part of the plant, and environmental conditions, such as \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Plant Species** & **Solvent** & **Method** & \
\begin{tabular}{c} **Concentration** \\ **[mgCE/gDM]** \\ \end{tabular} & **Ref.** \\ \hline \multirow{2}{*}{_Crithum maritium_} & n/a & n/a & 1.06 \(\pm\) 0.77 & [38] \\ \cline{2-5}  & Acetone (80\%) & & 0.63 & [39] \\ \hline \multirow{2}{*}{_Irula crithmoides_} & Acetone (80\%) & & 0.95 & [39] \\ \cline{2-5}  & _Ipomoa pes-caprae_ & Methanol (80\%) & & 19.67 \(\pm\) 2.54 & [34] \\ \cline{2-5}  & _Limonium delicatulum_ & Methanol (80\%) & Vanillin assay & 48.38 \(\pm\) 0.75 & [40] \\ \cline{2-5}  &
\begin{tabular}{c} Methanol \\ \end{tabular} & & 14.2 \(\pm\) 0.9 & [28] \\ \cline{2-5}  & Methanol & & 9.51 \(\pm\) 1.07 & [4] \\ \cline{2-5}  & Methanol & & 7.16 & [10] \\ \hline \multirow{2}{*}{_Mesembryanthemum nadiformum_} & Methanol & DMACA-HCl & 2.01 \(\pm\) 0.04 & [32] \\ \cline{2-5}  & Methanol (80\%) & & 20.52 \(\pm\) 4.32 & [34] \\ \hline \multirow{2}{*}{_Ranumria vermiculata_} & Dichloromethane & Vanillin assay & 27.98 \(\pm\) 1.01 & [41] \\ \cline{2-5}  & _Retama ratem_ & Acetone (60\%) & & 10.16 & [42] \\ \hline \multirow{2}{*}{_Salicornia rammississima_} & Acetone (70\%) & & \multirow{2}{*}{DMACA-HCl} & 32.5 \(\pm\) 4.6 & [5] \\ \cline{2-5}  & Acetone (80\%) & & & Not detected & [3] \\ \hline \multirow{2}{*}{_Salsola kali_} & Methanol & & 2.03 \(\pm\) 0.62 & [43] \\ \cline{2-5}  & _Salsola vermiculata_ & Acetone (80\%) & & & Not detected & [3] \\ \hline \multirow{2}{*}{_Salvadora persica_} & Methanol (80\%) & & 22.35 \(\pm\) 2.87 & [34] \\ \hline \multirow{2}{*}{_Sarccorornia fritticosa_} & Methanol & DMACA-HCl & 0.46 \(\pm\) 0.04 & [32] \\ \cline{2-5}  & _Sarccorornia perennis_ & Methanol & & 1.09 & [44] \\ \hline \multirow{2}{*}{_Suacda fritticosa_} & Methanol & & 7.76 \(\pm\) 0.28 & [31] \\ \cline{2-5}  & Methanol (80\%) & & 15.76 \(\pm\) 1.43 & [34] \\ \cline{2-5}  & Acetone & & 1.50 \(\pm\) 0.13 & [45] \\ \hline \multirow{2}{*}{_Suacda maritiuna_} & Methanol & DMACA-HCl & 1.21 \(\pm\) 0.05 & [32] \\ \hline \multirow{2}{*}{_Tamarix africana_} & Water & & 118.43 \(\pm\) 11.79 & [31] \\ \cline{2-5}  & _Tamarix gallica_ & Methanol & & 17.28 \(\pm\) 1.95 & [35] \\ \hline \multirow{2}{*}{_Thepsesia populnea_} & Methanol (80\%) & & 20.14 \(\pm\) 3.54 & [34] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._temperature, salinity, water stress, and light intensity [10]. Therefore, the composition extracts from the same species can vary, as can be seen in methanol extracts of _Salicornia ramossissima_ and _Tamariz gallica_.