# Seasonal Monitoring of Volatiles and Antioxidant Activity of Brown Alga _Cladosteplus spongiosus_
## 2 Results and Discussion
### Headspace Volatilome Variations of C. spongiosus
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Compound**} & \multirow{2}{*}{**Group**} & \multirow{2}{*}{**RI**} & \multicolumn{6}{c}{**Area \%**} \\ \cline{5-12}  & & & & **May** & & & **June** & & & **July** & & **August** \\ \cline{5-12}  & & & & **Fr** & **Dr** & **Fr** & **Dr** & **Fr** & **Dr** & **Fr** & **Dr** & **Fr** & **Dr** \\ \hline
68 & General &
\begin{tabular}{c} Terpene \\ (negative alcohol) \\ \end{tabular} & 1589 & 2 & - & 2.86 & - & - & - & - & - & - \\
74 & Phytune & Terpene (diperpene) & 1814 & - & - & - & - & 0.95 & - & - & - \\
75 & Hevalydrotherapy acetone &
\begin{tabular}{c} Terpene \\ (negative ketone) \\ \end{tabular} & 1800 & - & - & 0.3 & 1.36 & - & - & - & - \\ \hline \multicolumn{12}{c}{**OTRESS**} \\
2 & Dimethyl sulfide & Other & - & - & - & - & - & 0.99 & - & 1.96 \\
12 & 3-Methylbutanoic acid & Other (carboxylic acid) & - & - & 1.47 & - & 2.84 & - & - & - \\
13 & 2-Methylbutanoic acid & Other (carboxylic acid) & - & - & 0.76 & - & 1.87 & - & - & - \\
13 & 2-Methylbutanoic acid & Other (carboxylic acid) & - & 920 & 0.61 & 0.29 & 0.65 & 0.75 & 0.48 & - \\
12 & 3-Methylbutanoic acid & Other (carboxylic acid) & 982 & 6.56 & 4.8 & 0.26 & 0.55 & 0.48 & - \\
22 & 3-methylfuran & Other (formerly) & 996 & 0.26 & 0.57 & 0.42 & 0.76 & 0.62 & 1.04 & - & 0.81 \\
35 & -C+Cyclosterone & Other (y-lactone) & 1062 & - & 0.68 & - & 0.95 & - & - & - & - \\
39 & Hevalgenic acid & Other (carboxylic acid) & 1079 & - & 2.11 & - & 1.73 & - & - & - \\
42 & 3-Dimethylcyclohex-1-04 & Other (C+3-origenored) & 1134 & - & 2.81 & 1.13 & 4.35 & 1.94 & 1.6 & 2.22 & 1.13 \\
43 & -K+Geborneborne D & Other (C+3-origenored) & 1130 & - & - & 0.56 & 1.04 & 2.82 & - & 5.23 & - \\
45 & \{(\{\rm f(12)-burstburst\}\)-1-4 \(\}\) & Other (dicyclopentene) & 1158 & 1.34 & - & 1.32 & - & 0.84 & - & 0.44 & - \\  & cycloheptadieneD) &
\begin{tabular}{c} Dehydrogenase C \\ \end{tabular} & 1157 & - & - & - & 0.22 & - & 0.2 & - & - & - \\
47 & \{(\rm f(16)-14,-4) \(\}\) & Other (dicyclopentene) & 1175 & - & - & 0.22 & - & 0.2 & - & - \\
48 & \{\(\rm f(26)-tomacolor\) & Other (C+3-origenored) & 1490 & 2.53 & 1.13 & 2.71 & 1.96 & 3.66 & 2.6 & 4.76 & 1.62 \\  &
\begin{tabular}{c} Dehydroacetimidide \\ (4,4,4,7-trimethyl-4)-2, \\ (non) \\ \end{tabular} & 1533 & - & 2.04 & - & 0.98 & - & - & - & - & - \\ \hline \multicolumn{12}{c}{**Total Identified-**} & **91.96** & **78.05** & **90.3** & **94.45** & **92.62** & **89.99** & **91.61** & **100** \\ \hline \hline \end{tabular}  No. – order of the compounds elution on HP-SMS column, RIAliphatic ketones, such as octan-3-one, 6-methylhept-5-en-2-one, and (_E_,_Z_)-octa-3.5-dien-2-one, were more abundant in fresh samples (f1, f2). The fresh sample from June contained the highest percentage of aliphatic ketones (16.31%, f1; 20.58%, f2) (Tables 1 and 2), which play the role of pheromones in marine algae [12]. Benzene derivatives group dominated the fresh samples from May (33.86%, f1; 21.42%, f2), July (16.72%, f1; 27.87%, f2), and August (21.35%, f1; 35.34%, f2), as can be seen in Figures 1 and 2. Benzyl alcohol and benzaldehyde formed the majority of benzene derivatives. Benzaldehyde was the predominant compound in all fresh samples obtained by f2 (Table 2) and in all fresh samples (except June) obtained by f1 (Table 1). In contrast, benzyl alcohol was more abundant in the dry samples. The volatile benzene derivatives can be formed from phenylalanine when the side chain of a carbon skeleton shortens by C2-unit. This reaction most commonly occurs via the \(\beta\)-oxidative pathway [25]. The loss of benzaldehyde during air-drying could be due to its high volatility [26; 27; 28]. Terpenes, monoterepenes, and sesquiterpenes showed the largest proportion (Figures 1 and 2) in May dry sample (15.32%, f1; 13.94%, f2), mainly with the high abundance of monoterepene alcohols (_E_)-verbenol and _p_-cymen-8-ol (Tables 1 and 2). In the group of other compounds carboxylic acids, dictyopterenes, and C13-norisoprenoides were abundant.