Increased acute blood flow induced by the aqueous extract of Euterpe oleracea Mart. fruit pulp in rats in vivo is not related to the direct activation of endothelial cells

Scientific evidence supports the antioxidant, anti-inflammatory and anti-lipidemic properties of Euterpe oleracea Mart. (açaí), which all converge to reduce cardiovascular risks. Macerating the pulp of açaí fruit produces a viscous aqueous extract (AE) rich in flavonoids that is commonly used in food production. In addition to nutritional aspects, cardiovascular benefits are attributed to AE by traditional medicine. Evaluation of AE impact on blood flow in vivo in rats and investigation of the mechanism underlying this response in vitro in rat endothelial cells (RECs). For the measurement of acute blood flow, a perivascular ultrasound probe was used in Wistar rats. The in vitro assays employed REC to evaluate: concentration (1–1000 μg/mL) and time response (2–180 min) of AE in MTT cell viability assays; nitric oxide (NO) levels measurement and intracellular calcium handling using DAF-2DA and Fluo-4-AM, respectively; cellular biopterin content by HPLC; activation of Akt pathway using western blot analysis. For the chemical analyses of AE, stock solutions of the standards (+)catechin and quercetin were used for obtaining linear calibration curves. Identification and quantification of flavonoids in AE were based on comparisons with the retention times, increase in peak area determine by co-injection of AE with standards, UV–Vis scan and standard curves of known spectra. Results were expressed as mean ± standard deviation and data were analyzed using ANOVA followed by Tukey's post-test (p