[Analgesic effect of benzoylmesaconine]

"Tsumura Shuchi-Bushi Powder for Ethical Dispensing" (TJ-3021) is an herbal drug of processed Aconiti tuber that attenuates its toxicity. A greater part of mesaconitine which is regarded as a main analgesic component in processed Aconiti tuber is hydrolyzed into benzoylmesconine (BM) by its processing. In this study, the analgesic effect of BM was examined in comparison with that of TJ-3021 in mice and rats. BM (10 mg/kg, p.o.) depressed the acetic acid-induced writhing significantly. Its analgesic activity was almost similar in magnitude to that of TJ-3021 (300 mg/kg, p.o.). BM (30 mg/kg, p.o.) significantly increased the pain threshold ratio of paw pressure in repeated cold stress (RCS) rats, and its analgesic potency appeared to be equivalent to that of TJ-3021 (1000 mg/kg, p.o.). These results suggest that the analgesic activity of BM is strong enough for explanation of the analgesic effect of TJ-3021, and it might contribute to that of TJ-3021.