Poster Topical Area: Dietary Bioactive Components
Location: Hall D
Poster Board Number: 281
Objective: To investigate the mechanisms by which blueberry (BB) polyphenols improve vascular endothelial function in angiotensin II (Ang II)-stimulated human aortic endothelial cells (HAECs).
Methods: BB polyphenol extract (BBPE) was prepared using 70% methanol extraction followed by purification with chloroform and separation with ethyl-acetate. HAECs were treated with and without 200 µg/ml of BBPE for 12 h prior stimulation with Ang II for 8 and 12 h. Nitric oxide (NO) metabolites were determined using a colorimetric kit. Levels of reactive oxygen species (ROS) were determined after 30-min incubation with 2′,7′-dichlorodihydrofluorescein diacetate (H2DCFDA). Expression of phospho-endothelial NO synthase (eNOS), catalase (CAT), glutathione peroxidase (GPx1) as well as superoxide dismutase (SOD)1 and SOD2 were assessed by western blot. Results were analyzed using ANOVA followed by Tukey-Kramer post-hoc test.
Results: BBPE increased NO metabolite levels (1.3 ± 0.14 vs. 0.66 ± 0.11, P=0.01) and expression of phospho-eNOS (3.58 ± 0.89, vs. 1.28 ± 0.09, P=0.04) in Ang II stimulated cells compared to Ang II alone. ROS levels were decreased in Ang II stimulated cells pre-treated with BBPE compared to Ang II alone (0.70 ± 0.06 vs. 1.07 ± 0.05, P=0.03). GPx1 expression was increased by BBPE in the presence of Ang II compared to Ang II alone (3.67 ± 0.74 vs. 1.14 ± 0.23, P=0.05). SOD2 expression was increased in Ang II stimulated cells compared to control (3.82 ± 0.96 vs. 1.00 ± 0.00, P=0.04), no further changes in expression of SOD2 were observed following the addition of BBPE. Lastly, no significant changes were observed in SOD1 and CAT.
Conclusion: Altogether, our data partially elucidate the mechanisms by which BB polyphenols exert its protective effects on the endothelium as we demonstrate that BBPE increases not only the production of NO but also its bioavailability as it decreases ROS by increasing the expression of antioxidant enzymes.
Georgia State University