Ouratea species occur in the cerrado vegetation and some species are popularly used as tonic, astringent and anti-inflammatory. In the present work, we assayed the vasodilator effects of O. castanaefolia, O. spectabilisand O. semiserrata hydroethanolic extracts in aortic rings pre-contracted with phenylephrine. Only O. semiserrata stem extract (OS) produced significant vasodilatation (63 ± 3 %, n = 6), at the concentration of 100 mg/ml. Bioguided fractionation of OS afforded a proanthocyanidin-rich fraction that produced 100 ± 5 % vasodilatation (n = 6; concentration of 100 mg/ml). The total proanthocyanidin contents were assayed for OS and for the bioactive fractions using a spectroscopic method. Higher proanthocyanidin contents implied in increased vasodilator activity (r² = 0.9760), suggesting that compounds of this class may be regarded as responsible for the activity of O. semiserrata stem extract.
Ouratea semiserrata; Ouratea castanaefolia; Ouratea spectabilis; Vasodilator effect; Rat aorta; Total proanthocyanidin content
