Abstract

Chai hu is a Chinese herb growing both in northern and southern China. It has the English names hare’s ear and Chinese throwax root. Its botanical name is Bupleurum chinense D.C. The pharmaceutical preparation of the extract is called Radix bupleuri(R. Bupleuri). In this study the antinociceptive and antipyretic properties of R. bupleuriwere studied in mice. Yeast was used to induce pyrexia while acetic acid induced writhes and tail flick methods were used to investigate the nociceptive properties of the extract. Acute toxicity studies were also done to determine the median lethal dose LD₅₀. The extract significantly (P < 0.05) reduced acetic acid induced writhes compared with the control. The extract (50 mg/kg) showed a higher percentage inhibition of the acetic acid induced writhes compared to the positive control, acetyl salicylic acid (ASA). Tail flick model also revealed an increase in latency time for mice to flick their tail out of a warm bath maintained at a temperature of 50°C at the 25 mg/kg dose level compared to the control (P < 0.05). The extract also significantly (P < 0.01) reduced the temperature of rats after pyrexia induction. The results of this study justify the use of this extract by traditional Chinese herbalist as pain killer and for the treatment of fever.

Key words: Radix bupleuri, herbal, antipyretic, antinociceptive.