Location: Arkansas Children's Nutrition CenterTitle: Antioxidant capacities and anti-inflammatory effects of flavonoid compounds isolated from acai pulp (Euterpe oleracea Mart.)) Author
Submitted to: Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/3/2010
Publication Date: 10/1/2010
Citation: Kang, J., Li, Z., Wu, T., Jensen, G.S., Schauss, A.G., Wu, X. 2010. Antioxidant capacities and anti-inflammatory effects of flavonoid compounds isolated from acai pulp (Euterpe oleracea Mart.). Food Chemistry. 122(3):610-617. Interpretive Summary: Acai fruit (Euterpe oleracea Mart.) has been demonstrated to exhibit extremely high antioxidant capacity. Recent studies suggested that acai may prevent certain types of chronic diseases through antioxidant activities. Flavonoids were found to be major antioxidants in acai. In order to study individual antioxidant in acai, seven major flavonoids were isolated from freeze-dried acai pulp. Two of them were reported in acai for the first time. Their antioxidant capacities were evaluated by chemical-based oxygen radical absorbance capacity (ORAC) assay, two cell-based assays including antioxidant protection (CAP-e) assay and ROS formation in polymorphonuclear cells (ROS PMN) assay. Results from this study will help us find the major bioactive components in acai.
Technical Abstract: Acai fruit (Euterpe oleracea Mart.) has been demonstrated to exhibit extremely high antioxidant capacity. Seven major flavonoids were isolated from freeze-dried acai pulp by various chromatographic methods. Their structures were elucidated as orientin (1), homoorientin (2), vitexin (3), luteolin (4), chrysoeriol (5), quercetin (6), and dihydrokaempferol (7) by NMR, MS and compared with the reported literature. Compounds 3 and 6 were identified from acai pulp for the first time. Antioxidant capacities of these flavonoids were evaluated by oxygen radical absorbance capacity (ORAC) assay, cell-based antioxidant protection (CAP-e) assay and ROS formation in polymorphonuclear cells (ROS PMN) assay. ORAC values varied distinctly (1423.6 – 14817.4 micro mol TE/g) among the seven compounds based on numbers and positions of hydroxyl groups and/or other substitute groups. The ORAC values of aglycones are generally higher than that of glycosides. CAP-e results indicated that only three compounds (4, 6 and 7) could enter the cytosol and contribute to the reduction of oxidative damage within the cell. The ROS PMN assay showed that four compounds (2-3 and 6-7) demonstrated exceptional effects by reducing ROS formation in PMN cells, which produce high amounts of ROS under oxidative stress. The combined CAP-e and ROS PMN data indicate that compounds 2 and 3 had anti-inflammatory effects independent of their antioxidant capacity. In evaluating the antioxidant capacity of natural products, combining both chemical and cell-based assays will provide more comprehensive understanding of antioxidant effects and potential biological relevance.