Species of Erythroxylum genus are popularly used as anti-inflammatories and in the treatment of renal and respiratory disorders. Although it has been reported that species from the Erythroxylum genus induce cardiovascular effects, E. passerinum had not been studied specifically in this respect. However, previous phytochemical studies of E. passerinum demonstrated the presence of compounds which can have potential activity on the cardiovascular system. In this study, phytochemical screening of the ethanol extract of E. passerinum (EEEP) detected polyphenols, but not alkaloids. EEEP caused hypotension, bradycardia and vasorelaxation in rats. The vasorelaxation was attenuated by Nw-nitro-L-arginine methyl ester (L-NAME) or L-NAME + indomethacin (INDO), but not by INDO alone. Vasorelaxation was also significantly attenuated after endothelium removal or after incubation with high K+, 4-aminopyridine, glibenclamide or tetraethylammonium, but was not affected by pre-contraction with serotonin. Thus, EEEP induces hypotension and endothelium-dependent and independent vasorelaxation, which seems to involve the nitric oxide and K+-channels.
Keywords: Erythroxylum passerinum; nitric oxide; phytochemical; polyphenol; vasodilatation.