Antioxidant and DNA Protection Effects of Taurine by Electron Spin Resonance Spectroscopy - Advances in Experimental Medicine and Biology - page 159

Fig. 17.1 DPPH radical scavenging activity (%) ( a ) and ESR spectra ( b ) according to the taurine
treatment at various concentrations (0.0625-1 mg/mL). Each bar represents the mean ± SEM of
three independent experiments. The dashed horizontal line indicates the value at the concentration
inhibiting 50% of free radical generation (IC 50 )
screen the free radical scavenging ability of compounds or antioxidant activity of plant
extracts. The effect of taurine on DPPH radical scavenging activity is shown in Fig. 17.1 .
DPPH radical scavenging activity, at the concentration inhibiting 50% of free radical
generation (IC 50 ), was 0.144 mg/mL as shown in Fig. 17.1a . Additionally, a decrease of
ESR signals was observed with the dose increment of taurine compared to the control
(Fig. 17.1b ).
Figure 17.2 shows the hydroxyl radical scavenging activity and ESR spectra of
the taurine. As shown in Fig. 17.2a , the IC 50 of hydroxyl radical scavenging activ-
ity was 0.241 mg/mL. Hydroxyl radicals generated in the Fe 2+ /H 2 O 2 system were
trapped by DMPO, forming a spin adduct detected by ESR spectrometry, and the
typical 1:2:2:1 ESR signal of the DMPO-OH adduct was observed; see Fig. 17.2b .
In the present study, ESR assays showed that hydroxyl radical scavenging activity
of taurine at various concentrations (0.0625~1 mg/mL) was elevated with a
decrease of ESR signals in a dose-dependent manner.
Figure 17.3 shows the superoxide radical scavenging activity and ESR spectra of
the taurine. In our present study, ESR assays showed that superoxide radical scav-
enging activity of taurine at various concentrations (0.25 ~ 1 mg/mL) was elevated
with a decrease of ESR signals in a dose-dependent manner. However, the superox-
ide radical scavenging activity by taurine was weaker than for DPPH and hydroxyl
radical scavenging.
In the present study, the IC 50 of alkyl radical scavenging activity was
0.206 mg/mL. In addition, the decrease of ESR signal was observed with the
dose increment of the taurine (Fig. 17.4 ). These results indicate that the taurine
effectively scavenged various reactive radicals, including DPPH, hydroxyl,
superoxide, and alkyl radicals.