Objective: To study the antipyretic effect and the mechanism of Peristrophe japonica by comparing with variances of the antipyretic effect among water extract of P. japonica

ligarine fraction and water fraction. Method: The rat febrile model was induced by injecting fresh yeast subcutaneously and treated with water extract of P. japonica

ligarine fraction and water fraction

then the rectal temperature was monitored to show the differences of effect from those groups.The contents of interleukin-1 (IL-1)

interleukin-6 (IL-6) in blood serum and cyclic adenosine monophosphate(cAMP)

prostaglandin E2(PGE2) in the hypothalamus were measured by radioimmunoassav (RIA)

respectively. Result: Three drug administration groups(including water extract of P. japonica

ligarine fraction and water fraction) showed marked antipyretic effect on the yeast-induced fever(P<0.05) and the effects were stronger on the ligarine fraction and water fraction groups than water extract of P. japonica group. The ligarine fraction group showed remarkable decreased the contents of IL-6 in blood serum and PGE2

cAMP in the hypothalamus of febrile rats. Conclusion: The water extract ofP. japonica

ligarine fraction and water fraction all have obvious antipyretic effect

but the effect of ligarine fraction and water fraction are stronger than that of water extract of P. japonica

which might be related to decreasing the levels of IL-6 in serum and the interferencing the content of PGE2

cAMP in the hypothalamus.