Antioxidant activity of black currant anthocyanin aglycons and their glycosides measured by chemiluminescence in a neutral pH region and in human plasma.

The antioxidant activity of nine anthocyanin glycosides was measured in a neutral pH region using a chemiluminescence (CL) emission system in the presence of an H(2)O(2)-acetaldehyde system, and the intensities were found to be affected by three factors, pH value and both moieties of the aglycon and C-3 sugar. With an increase in pH from 4.0 to 9.0, the CL intensities increased from pH 5.0, reached their maxima at pH 6.0-7.0, and decreased at pH 9.0. Comparison of the intensities among the 3-glucosides with five different aglycons and the 3-glycosides with three different sugar moieties at C-3 showed that their strongest intensities were given by the delphinidin aglycon and 3-rutinosyl moiety, respectively. Monitoring of the CL intensity of human blood plasma for 8 h after oral administration of black currant anthocyanins (BCA) showed a rapid increase until 2 h, and a significant difference (P < 0.05) was recognized at 1-8 h.