Formation of stable free radicals from kampo medicines TJ-9, TJ-15, TJ-23, TJ-96, TJ-114 and their antioxidant effect on low density lipoproteins.

Abstract

The Japanese herbal Kampo medicines TJ-9 (A), TJ-15 (B), TJ-23 (C), TJ-114 (D) and TJ-96 (E) were effective (2-5x less than alpha-tocopherol) in inhibiting a copper-induced peroxidation of low density lipoprotein. Kampo medicines dissolved in n-butanol formed stable free radical(s), detected by EPR spectroscopy as a single asymmetric line with g-value g = 2.005. The radical concentration increased in the order: C less than D approximately A approximately E less than B. When the Kampo medicines were oxidized in n-butanol by excess of PbO2 their radical concentration increased 7-15 fold and was in the order C less than D less than A approximately E much less than B. A relationship between the potency of the medicines to inhibit peroxidation of LDL and their ability to form stable free radicals upon oxidation was observed. The medicine which formed more radicals was more efficient in inhibiting peroxidation of LDL. In order to study whether Kampo medicines can reduce alpha-tocopherol radical, the alpha-tocopherol radical was generated by the reaction of alpha-tocopherol with UV irradiated di-tert-butylperoxide and by autooxidation of alpha-tocopherol in n-butanol (25 microliters ml-1) in air. In both systems vitamin-C greater than Kampo B decreased the concentration of the alpha-tocopherol radical and the EPR spectrum of Kampo B stable radical(s) appeared. The effect of other Kampo medicines was not clearly seen since their EPR spectra were superimposed with the spectrum of the alpha-tocopherol radical. The results indicate that Kampo medicines possess electron donor properties and ability to form stable radical(s). The results may contribute to understanding beneficial effects of Kampo medicines in diseases in which free radical damage is suggested.