SCAVENGING EFFECTS OF BAICALIN ON FREE-RADICALS AND ITS PROTECTION ONERYTHROCYTE-MEMBRANE FROM FREE-RADICAL INJURY

Using electron spin resonance(ESR) spin trapping technique, we found t hat baicalin (B) could scavenge hydroxyl radicals generated from Fento n reaction. It also could scavenge superoxide radicals generated from the reaction system containing xanthine (X) and xanthine oxidase (XO), as was found by using chemiluminescence (CL) method. Kinetic studies on the competition between baicalin and a spin trap 5,5-dimethyl-1-pyr roline-1-oxide (DMPO) in trapping OH showed that baicalin had a kineti c reactive rate constant of the order of 7.7 x 10(11) M(-1) s(-1) in i ts reaction with OY and the studies on the competition between baicali n and ferricytochrome.c(f.c.) in trapping O-2(-) gave a kinetic reacti ve rate constant of 3.2 x 10(6) M(-1) s(-1) for baicalin in its reacti on with O-2(-). Furthermore, we have investigated the protective effec ts of baicalin on erythrocyte membranes from hydroxyl free radical inj uries. The results showed that baicalin could reduce hydrogen peroxide -induced hemolysis, protect the conformation of sulfhydryl groups (-SH ) on membrane proteins and the membrane fluidity of erythrocytes incub ated with hydrogen peroxide. The results indicated that baicalin could protect the membranes of erythrocytes from free radical injuries, and it was even more effective than alpha-tocopherol.