Weak Inhibitory Effects of Anthocyanins on Human Aldehyde Oxidase Activity: An In Vitro Study.

Aldehyde oxidase (AO) plays an important role in the metabolism of antitumor and antiviral drugs, including methotrexate, favipiravir, and acyclovir. The consumption of blueberry fruits or their extracts, which contain large amounts of anthocyanins, has recently increased. The intake of large amounts of anthocyanins occurs through the frequent consumption of blueberries or their functional foods, which may result in unwanted interactions between anthocyanins and medicinal drugs. Therefore, the present study examined the inhibition of AO by anthocyanins, anthocyanidins, and blueberry extracts in human liver cytosol using a HPLC assay. A comparison of the 50% inhibitory concentration (IC50) values of the test compounds showed that anthocyanidins slightly suppressed AO activity, whereas the inhibitory effects of anthocyanins and blueberry extracts were negligible. The inhibitory activities of the anthocyanins tested were approximately 60- to 130-fold weaker than that of the positive control menadione and were almost negligible. Furthermore, they were approximately 2,000-fold less potent than that of raloxifene, a typical AO inhibitor, and, thus, unlikely to interfere with drug metabolism by AO. In addition, since the plasma concentrations of anthocyanins after their administration were generally lower than the IC50 level, the inhibition of AO substrate metabolism by anthocyanins does not appear to be severe.

Total Anthocyanin Content, Total Phenolic Content, and Antioxidant Activity of Various Blueberry Cultivars Grown in Togane, Chiba Prefecture, Japan.

More than fifty cultivated varieties of blueberries are grown under the same processing conditions on the farm at Chiba Prefectural Agricultural College in Japan. The fruits from 51 blueberry cultivars, including 16 rabbiteye (RE) cultivars (Vaccinium ashei Reade) and 35 highbush (HB) cultivars (Vaccinium corybosum L.), were evaluated for total anthocyanin contents, phenolic contents, and their contribution to antioxidant activity among cultivars. Total anthocyanin contents varied from 0.74±0.21 ("Barkley") to 4.27±0.18 ("Suwannee") mg as cyanidin-3-glucoside (Cy-3-GC) equivalent/g fresh-weight (fw), with phenolic contents in the range of 0.77±0.14 ("Floridablue") to 3.69±0.89 ("Suwannee") mg of gallic acid equivalent (GAE)/g fw, which strongly correlated with antioxidant activities assessed using the DPPH and ORAC methods, respectively. Total anthocyanin and phenolic contents were both significantly higher (p<0.05) in RE blueberries than in HB blueberries. Furthermore, the total phenolic values were significantly higher for the RE family than for the HB family (p<0.01). In comparisons of two species, the major anthocyanidin identified were malvidin in RE blueberries and delphinidin in HB blueberries. This result suggests that some RE blueberries, especially "Suwannee," "Homebell" and "Climax," are suitable supply sources with high in vitro antioxidant capacity. This study would be helpful to the quality-oriented cultivation of blueberry.

Use of in-gel peroxidase assay for cytochrome c to visualize mitochondrial complexes III and IV.

The in-gel activity assay (IGA) is a powerful technique that uses enzymatic activity and compares intensities of detected bands in mitochondrial respiratory chain supercomplexes, and it is applicable to eukaryotic organisms. However, no IGA has been established for complex III because of the difficulty of access by ubiquinol, a substrate for complex III. Herein, we demonstrate that cytochrome c (Cyt c) showed peroxidase activity on IGA as a component of complexes III and IV. We used pre-incubation with sodium dodecyl sulfate (SDS) before IGA to loosen complexes in the gel after high-resolution clear native polyacrylamide gel electrophoresis (hrCN-PAGE), a refinement of blue native PAGE. The signals of IGA based on peroxidase activity were obtained using enhanced chemiluminescence solution. Then, the gel was directly used in western blotting or hrCN/SDS two-dimensional PAGE. Our findings indicate that IGA for Cyt c reflected the indirect activity of complexes III and IV.