Inhibitory effects of Euterpe oleracea Mart. on nitric oxide production and iNOS expression

The palm Euterpe oleracea is a plant of great economic value in Brazil. Although the heart of palm extracted from its trunk is considered a delicacy the world over, its fruits are popular only among Brazilians. In some poor regions of Brazil, there are reports on the popular use of its juice in the treatment of several disorders, mainly those of oxidative onset as cardiovascular ones. Because of its wide utilization; because there are very few scientific studies of this species, and to discover if its use in folk medicine for problems related with oxidation is in fact justifiable, we decided, in this study, to evaluate the effects of Euterpe oleracea flowers, fruits and spikes fractions on: nitric oxide (NO) production, NO scavenger capacity, and on the expression of inducible nitric oxide synthase enzyme, as well. Results showed that the fractions obtained from fruits were the most potent in inhibiting NO production, followed by those from flowers and spikes. Only in high doses, did some fractions reduce cell viability. Reduction on NO production was not due to NO scavenger activity. These results were accompanied by inhibition of iNOS expression. The more pronounced effect was observed in the fractions in which the concentration of cyanidin-3-O-glucoside and cyanidin-3-O-rhamnoside were higher. To sum up, our results indicate that fractions from Euterpe oleracea inhibits NO production by reducing the levels of inducible nitric oxide synthase expression.