Studies on Taiwan folk medicine, thang-kau-tin (II): Measurement of active oxygen scavenging activity using an ESR technique.

Using an electron spin resonance (ESR) technique, we measured the superoxide radical (O2) and hydroxyl radical (OH) scavenging activity from Mallotus repandus (Willd.) Muell.-Arg., Bauhinia championii Benth., Uncaria hirsuta Haviland and Uncaria rhynchophylla Miquel. O2- and OH were detected as spin adducts of spin traps 5,5-dimethylpyrroline-N-oxide (DMPO). The scavenging potencies of water extracts of crude drugs were evaluated in terms of their ability to reduce the peaks of spin adducts. The extract of B. championii showed the greatest superoxide radical and hydroxyl radical scavenger activity.