# Plasma-Activated Water Affects the Antioxidant Contents in Water Spinach
## 3 Results and Discussion
### TP Content
Plasma treatment of seeds would lower the TP  
Figure 4: Comparison of TP content in water spinach with different plasma treatments grown in different soil. NTS: non-treated seed; NTW: non-treated water; PAW: plasma-activated water; PTS: PAW-treated seed. Different uppercase letters indicate the significant difference between plasma treatment, while different lowercase letters indicate the significant difference between cultivation soil. \begin{table}
\begin{tabular}{l l l l l} \hline \hline \multirow{2}{*}{**Treatment**} & \multicolumn{2}{c}{**TP Content (mg GAE/g DM) of the Water Spinach Planted in**} & \multirow{2}{*}{\(p\)**-Value**} \\ \cline{2-2} \cline{4-4}  & **Control Soil** & & **Cd-Added Soil** & & \\ \hline NTS + NTW & 14.39 \(\pm\) 0.50 \({}^{\text{Aa}}\) & 17.09 \(\pm\) 0.72 \({}^{\text{Eb}}\) & 19.06 \(\pm\) 0.29 \({}^{\text{Hc}}\) & \textless{}0.001 *** \\ NTS + PAW & 17.73 \(\pm\) 0.66 \({}^{\text{BCd}}\) & 18.04 \(\pm\) 1.20 \({}^{\text{Ed}}\) & 16.82 \(\pm\) 0.40 \({}^{\text{Gd}}\) & 0.246 \\ PTS + NTW & 16.23 \(\pm\) 1.19 \({}^{\text{Be}}\) & 14.85 \(\pm\) 1.11 \({}^{\text{De}}\) & 15.20 \(\pm\) 0.18 \({}^{\text{Fe}}\) & 0.256 \\ PTS + PAW & 18.83 \(\pm\) 0.91 \({}^{\text{Ch}}\) & 16.98 \(\pm\) 1.25 \({}^{\text{Eg}}\) & 14.94 \(\pm\) 0.37 \({}^{\text{Ff}}\) & \textless{}0.01 ** \\ \(p\)-value & \textless{}0.01 ** & \textless{}0.05 * & \textless{}0.0001 *** & \\ \hline \hline \end{tabular} Note: Different uppercase letters indicate the significant difference between plasma treatment, while different lowercase letters indicate the significant difference between cultivation soil (* \(p<\) 0.05, ** \(p<\) 0.01, *** \(p<\) 0.0001). Samples used in the analysis are the mixtures of three pots of plants and the data shown are the average analysis values of three repeats. NTS: non-treated seed; NTW: non-treated water; PAW: plasma-activated water; PTS: PAW-treated seed.  
\end{table} 
Table 3: Comparison of TP content in water spinach with different plasma treatments grown in different soil of the Phase-1 pot experiment. content of water spinach grown in Cd-added soil, but irrigated PAW of the plasma-treated seed could improve the situation. The TP content of the NTS + PAW treatment group showed an improvement (18.04 \(\pm\) 1.21 mg GAE/g); however, the usage of PAW seems to increase the TP content in the water spinach cultivated in Cd-added soil, with no observed significant difference. The highest TP content value was obtained by NTS + NTW-treated water spinach (19.06 \(\pm\) 0.29 mg GAE/g), which was planted in the Pb-added soil. The TP content in water spinach was decreased by 11.8% in the NTS + PAW treatment group compared to that in the NTS + NTW group by 20.3% in the PTS + NTW group and 21.6% in the PTS + PAW treatment group. Results showed that the plasma-treated seed or irrigation PAW did not increase the TP content of water spinach grown in Pb-added soil. Several studies have shown that, under heavy metal stress, phenolic compounds can act as metal chelators and, alternatively, phenolic compounds could directly scavenge molecular species of active oxygen [34; 35; 36]. [PERSON] et al. [46] reported that Pb application significantly enhanced the phenolic acids and flavonoids content of _Prosopis factra_. [PERSON] et al. [33] demonstrated that Pb in soil significantly altered the content of polyphenolic compounds of basil (_Ocimum basilicum_ L.); also, different Pb levels can have different effects on polyphenolic compounds. The number of polyphenolic compounds decreased with increasing Pb content from 0 to 50 ppm, and increased again at 75 ppm. [PERSON] et al. [31] found that the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and TP content values of basil (_Ocimum basilicum_ L.) increased with Cd application (from 2.5 to 40 mg/kg). Additionally, [PERSON] et al. [30] observed oxidative stress induced by Cd and an increase in TP content in lettuce (_Lactuca sativa_ Linn.).