S-allylmercaptocysteine scavenges hydroxyl radical and singlet oxygen in vitro and attenuates gentamicin-induced oxidative and nitrosative stress and renal damage in vivo

Table 2 Antioxidant enzymes activity in renal cortex from the four groups of rats studied on day 5

	Control	Gentamicin	SAMC	Gentamicin+SAMC
Mn-SOD (U/mg protein)	7.4 ± 0.4	4.6 ± 0.7	7.8 ± 1.2	7.9 ± 1.4
Cu,Zn-SOD (U/mg protein)	26.7 ± 2.8	28.1 ± 2.2	24.1 ± 1.1	28.6 ± 3.4
GPx (U/mg protein)	0.16 ± 0.007	0.09 ± 0.007^a	0.14 ± 0.009	0.12 ± 0.007^a
GR (U/mg protein)	0.037 ± 0.002	0.03 ± 0.002^a	0.039 ± 0.002	0.041 ± 0.0007^b
CAT (k/mg protein)	0.55 ± 0.04	0.29 ± 0.03^a	0.35 ± 0.01^a	0.26 ± 0.03^a

Values are mean ± SEM; ^ap < 0.05 vs. CT, ^bp < 0.001 vs GM n = 4–5. CT, control; GM, gentamicin; SAMC, S-allylmercaptocysteine; Mn-SOD, manganese-dependent superoxide dismutase; Cu,Zn-SOD, copper/zinc-dependent superoxide dismutase; GPx, glutathione peroxidase; GR, glutathione reductase; CAT, catalase. NOTE: The decomposition of H₂O₂ by CAT contained in the samples follows a first-order kinetics as given by the equation k = 2.3/t logAo/A where k is the first-order reaction rate constant, t is the time over which the decrease of H₂O₂ due to CAT activity was measured (15 s), and Ao and A are the optical densities at times 0 and 15 s, respectively.