Abstract: A medicine or reagent comprising a bipyrazole derivative of the following formula (I), ##STR1## wherein R.sub.1 and R.sub.2 are individually a hydrogen atom, aryl group, alkyl group having 1-5 carbon atoms, or alkoxycarbonylalkyl group having a total of 3-6 carbon atoms, R.sub.3 and R.sub.4 are individually a hydrogen atom, alkyl group having 1-5 carbon atoms, cycloalkyl group having 5-7 carbon atoms, hydroxyalkyl group having 1-3 carbon atoms, benzyl group, naphthyl group, or substituted or unsubstituted phenyl group, as an active component. The medicine is useful for effectively capturing active oxygen and free radicals which cause adult diseases such as cerebral ischemia, heart disease, digestive system disease, and carcinoma, as well as inflammation, and for diagnosing diseases associated with in vivo free radicals.

Abstract: Method for detecting peroxidase or hydrogen peroxide with high sensitivity. Both peroxidase and hydrogen peroxide are prepared such that one of them is overabundant to the other. Phenoxy radicals are produced from a p-substituted phenol compound by the action of peroxidase in the presence of hydrogen peroxide. The free radicals are trapped by a hydroxy amine compound, and stable radical species are produced. Electron spin resonances of the stable radical species are measured.