Potentiation by febrifugine of host defense in mice against Plasmodium berghei NK65

The effect of febrifugine, the main alkaloidal constituent of an antimalari al crude drug, Dichroa febrifuga Lour., on protective immunity in mice infe cted with erythrocytic stage Plasmodium berghei NK65 was investigated. Febr ifugine was administered orally, at a dose of 1 mg/kg/day, to mice before a nd/or after they were infected intraperitoneally with 2 X 10(6) parasitized red blood cells. Then, mortality and the levels of parasitemia and plasma NO3- [a degradation product of nitric oxide (NO)] were monitored. Febrifugi ne significantly reduced the mortality and the level of parasitemia. The pl asma NO3- concentration began to rise within 2 days after treatment with fe brifugine and declined to normal in 2 days when the mice were treated orall y with febrifugine once a day for 3 consecutive days before parasite infect ion. This antimalarial activity of febrifugine was reduced by both N-G-mono methyl-L-arginine and aminoguanidine. These results indicate that the incre ased production of NO by febrifugine plays an important role in host defens e against malaria infection in mice. (C) 1999 Elsevier Science Inc.