Anti-inflammatory action of Pluchea sagittalis: involvement of an antioxidant mechanism.

Pluchea sagittalis, (Lam.) Cabr., a popular medicinal herb grown in South America, was studied for anti-inflammatory and antioxidant activities. The anti-edema action of P. sagittalis aqueous extract was assayed in different models of inflammation: 1) the mouse ear edema test induced by arachidonic acid and croton oil; 2) the rat hind-paw edema test produced by several inflammatory inductors: carrageenan, dextran, zymosan, platelet-activating factor (PAF) and arachidonic acid; 3) a subacute model based on the rat carrageenan air-pouch granuloma test. Blood leukocyte free radical production was measured by flow cytometry with 2',7'-dichlorofluorescin diacetate (DCFH-DA) in vivo, in rats with induced air-pouch granuloma, and in a model in vitro. stimulating leukocytes with hydrogen peroxide. The aqueous extract of P. sagittalis showed a marked anti-inflammatory effect in both ear edema tests, dextran and carrageenan hind-paw edemas and carrageenan air-pouch model. It also had a potent antioxidant activity in blood leukocytes, both in vivo and in vitro. Our results correlate the reduction of free radical production with the anti-inflammatory effect of this plant.