Scavenging effects of metal complexes of water-soluble thiacalix[4]arenetetrasulfonate on superoxide anion radicals.
The scavenging effects of metal complexes of thiacalix[4]arenetetrasulfonate (Me-TCAS[4], Me=H₂, Fe³(+), Mn³(+), Mn²(+), Cu²(+), and Zn²(+)) on superoxide anion radicals (O₂⁻) generated from the xanthine-xanthine oxidase system were investigated by the nitroblue tetrazolium (NBT) method and electron spin resonance (ESR) spin-trapping method using 5,5-dimethyl-1-pyrroline-N-oxide as a trapping reagent. As a reference, calix[4]arenetetrasulfonate (H₂)-CAS[4]), calix[6]arenehexasulfonate (H₂-CAS[6]) and calix[8]areneoctasulfonate (H₂-CAS[8]) were also examined. The results by the NBT method indicated that Fe³(+)- and Mn³(+)-TCAS[4] exhibited the highest O₂⁻ scavenging activity among Me-TCAS[4] and H₂-CAS[n] (n = 4, 6, 8) in this study. The IC₅₀ values of Fe³(+)- and Mn³(+)-TCAS[4] for O₂⁻ scavenging activity were estimated to be 5.3 and 7.8 µM, respectively, and were almost the same as those of tannin acid, catechin and their derivatives, which are known as very effective scavengers of O₂⁻. Scavenging activities were in the order of Fe³(+)- and Mn³(+)-TCAS[4]>>Mn²(+)-, Cu²(+)-, and Zn(2+)-TCAS[4]>>H(2)-TCAS[4] and H₂-CAS[n] (n=4, 6, 8). Each activity of Me-TCAS[4] (Me=Fe³(+), Mn³(+), Mn²(+), Cu²(+), and Zn²(+)) was higher than that of the corresponding metal ion, indicating that H₂-TCAS[4] has the ability to raise the activity of the metal ion itself by forming a complex. Also, the ESR spin-trapping method revealed that Fe³(+)- and Mn³(+)-TCAS[4] showed high O₂⁻ scavenging activities, similarly to the results by the NBT method.
Department of Biological Chemistry, Faculty of Science, Okayama University of Science, Kita, Okayama, Japan. odo@dbc.ous.ac.jp
Junichi
J
Odo
Ayumi
A
Kimura
Atsushi
A
Matsu-Ura
Yuki
Y
Ohnishi
Yoshiro
Y
Saeki
Akiko
A
Yoshida
Ken-Ichiro
K
Hayashi
Masahiko
M
Inoguchi
Takahiko
T
Ueki
D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D016166:Free Radical Scavengers / Q000138:chemical synthesis / Q000737:chemistry*; D010636:Phenols / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D013481:Superoxides / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D056831:Coordination Complexes; D016166:Free Radical Scavengers; D010636:Phenols; C446239:thiacalix(4)arenetetrasulfonate; D014867:Water; D013481:Superoxides