Table 2.

Effect of estradiol and sinapic acid on the serum concentrations of nonenzymatic antioxidants and the serum activity of antioxidative enzymes.

Parameter/group	SHAM	OVX	ESTR	SA5	SA25
GSH (nmol/ml)	1.197 ± 0.032	1.090 ± 0.024∗	1.187 ± 0.041#	1.183 ± 0.033	1.239 ± 0.026##
GSSG (nmol/ml)	0.305 ± 0.013	0.357 ± 0.030	0.317 ± 0.027	0.377 ± 0.024	0.324 ± 0.029
GSH/GSSG	3.994 ± 0.245	3.161 ± 0.266	3.892 ± 0.356	3.231 ± 0.297	4.060 ± 0.532
TAC (μmol/ml)	1.27 ± 0.18	0.89 ± 0.06	1.07 ± 0.13	1.18 ± 0.21	0.94 ± 0.04
SOD (U/mg of protein)	5.22 ± 0.19	6.20 ± 0.34∗∗	5.35 ± 0.15##	5.87 ± 0.14∗	5.57 ± 0.16#
CAT (nmol/min/mg of protein)	0.52 ± 0.08	0.74 ± 0.19	0.60 ± 0.08	0.70 ± 0.13	0.63 ± 0.10

Sinapic acid at doses of 5 mg/kg (SA5) and 25 mg/kg (SA25) or estradiol ((ESTR) 0.2 mg/kg) was administered orally to rats once daily for 28 days. SHAM: sham-operated control rats; OVX: ovariectomized control rats; GSH: reduced glutathione; GSSG: oxidized glutathione; TAC: total antioxidant capacity; SOD: superoxide dismutase; CAT: catalase. Results are presented as the mean ± SEM. The level of TAC is presented in Trolox equivalents. One unit of SOD was the amount of enzyme needed to exhibit 50% dismutation of the superoxide radical. One-way ANOVA followed by Fisher's LSD test was used for evaluation of statistical significance of the results. ^∗p ≤ 0.05, ^∗∗p < 0.01: significantly different from the SHAM control rats. ^# p ≤ 0.05, ^##p < 0.01: significantly different from the OVX control rats. No statistically significant differences in results for GSSG, GSH/GSSG ratio, TAC, and CAT were demonstrated in ANOVA.