*3.5. E*ff*ects on MDA Level*

The MDA level, an indicator of lipid peroxidation, was increased (*p* < 0.001) (Figure 5E) in the Sco-treated fish as compared to the control group. REO administration significantly reduced the MDA level (*p* < 0.001) (Figure 5E) to near the control level in Sco-treated fish.

**Figure 5.** *Rosmarinus o*ffi*cinalis* essential oil (REO: 25, 150, and 300 μL/L) exhibited an anti-AChE effect and improved brain antioxidant status. The enzyme's specific activities: (**A**) AChE; (**B**) SOD; (**C**) CAT; (**D**) GPX; and (**E**) MDA level. Values are means ± S.E.M. (*n* = 10). For Tukey's post hoc analyses: (**A**) Control vs. Sco (100 μM): ### *p* < 0.0001, Sco vs. REO (25 μL/L): ### *p* < 0.0001, Sco vs. REO (150 μL/L): ### *p* < 0.0001, and Sco vs. REO (300 μL/L): ### *p* < 0.0001; (**B**) Control vs. Sco (100 μM): # *p* < 0.01, Sco vs. REO (25 μL/L): ### *p* < 0.0001, Sco vs. REO (150 μL/L): ### *p* < 0.0001, and Sco vs. REO (300 μL/L): ### *p* < 0.0001; (**C**) Control vs. Sco (100 μM): ## *p* < 0.001, Sco vs. REO (25 μL/L): ### *p* < 0.0001, Sco vs. REO (150 μL/L): ### *p* < 0.0001, and Sco vs. REO (300 μL/L): ### *p* < 0.0001; (**D**) Control vs. Sco (100 μM): ### *p* < 0.0001, Sco vs. REO (25 μL/L): ### *p* < 0.0001, Sco vs. REO (150 μL/L): ### *p* < 0.0001, and Sco vs. REO (300 μL/L): ### *p* < 0.0001; and (**E**) Control vs. Sco (100 μM): ## *p* < 0.001, Sco vs. REO (25 μL/L): ### *p* < 0.0001, Sco vs. REO (150 μL/L): ### *p* < 0.0001, and Sco vs. REO (300 μL/L): ### *p* < 0.0001.

Pearson correlation coefficient (*r*) was used to test the linear association among cognition, antioxidant enzymes, and lipid peroxidation (Figure 6). A high negative correlation for the time spent in the top zone of the tank vs. MDA (*n* = 10, *r* = −0.863, *p* < 0.001) (Figure 6A) and the time spent in novel arm vs. MDA (*n* = 10, *r* = −0.737, *p* < 0.001) (Figure 6B) was observed. The negative value of the

Pearson correlation coe fficient indicates that the improvement of behavioral scores in specific tests such as NTT and Y-maze is well correlated with a low level of MDA, a marker of lipid peroxidation. In addition, strong negative correlations were evidenced by linear regression for AChE vs. the time spent in the top zone of the tank (*n* = 10, *r* = −0.645, *p* < 0.001) (Figure 6C) and AChE vs. the time spent in novel arm (*n* = 10, *r* = −0.597, *p* < 0.01) (Figure 6D). However, a positive significant correlation for AChE vs. MDA (*n* = 10, *r* = 0.608, *p* < 0.01) (Figure 6E) was noticed when linear regression was calculated. In this case, the negative and positive values of the Pearson correlation coe fficient indicate that increasing behavioral scores is well correlated with decreasing of AChE activity and MDA level. Pérez-Fons et al. [40] demonstrated a relationship between the antioxidant capacity and e ffect of rosemary (*Rosmarinus o*ffi*cinalis* L.) polyphenols on membrane phospholipid order. By using the Pearson correlation coe fficient (*r*) determination, we evidenced that improving memory performance in Sco-treated rats is related to increasing antioxidant enzyme activity along with a diminished level of lipid peroxidation, supporting REO neuroprotective profile. No significant correlation between biochemical parameters was observed.

**Figure 6.** Correlation analyses between behavioral and biochemical parameters (Pearson's correlation, *n* = 10): ( **A**) time spent in tope zone (s) vs. MDA; (**B**) time spent in novel arm (s) vs. MDA; ( **C**) AChE vs. time spent in tope zone (s); ( **D**) AChE vs. time spent in novel arm (s) and (**E**) AChE vs. MDA. Data expressed are time spent in the top zone (s), time spent in novel arm (s), AChE (nmol/min/mg protein), and MDA (nmol/mg protein).
