ABSTRACT
Anthocyanin, a reddish pigment, is a family of flavonoids distributed in many colored food materials, for example, blueberry, blackcurrant, strawberry, and eggplant, and we ingest large amounts of these in our daily diets. Recently, many physiological functions were reported, such as improvement of vision [1],
α-glucosidase inhibitory activity [2], induction of apoptosis [3], anticancer activity [4], and antioxidant activity [5]. In our study, we focused on the antioxidant activity of anthocyanin [6]. However, isolation of anthocyanin is difficult compared to other flavonoids such as catechin because of their unstable nature [7]. Hence, the structure-activity relationship of anthocyanin, except for a few purified
anthocyanins [8], has not been sufficiently studied. In bilberry (a wild-type blueberry), 15 anthocyanins exist (Figure 28.1). Thus, bilberry is good sample for studying the structure-reactivity relationship of anthocyanin toward reactive oxygen species (ROS) and reactive nitrogen species (RNS). To discuss the reaction of anthocyanin, we first established the capillary zone electrophoretic (CZE) method for simultaneous separation of bilberry anthocyanins [9-11]. Using this method, we evaluated the structure-reactivity relationship of anthocyanins found in the bilberry extract in reactions toward ROS in vitro including hydroxyl radical (•OH), superoxide anion (O-2), hydroperoxide (H2O2), and singlet oxygen (1O2) [12,13]. Reactions of anthocyanins towards RNS such as nitric oxide (NO) and peroxynitrite (ONOO•) were also studied [14]. To discuss the in vivo antioxidant activity of anthocyanins, it is important to understand their absorption and distribution mechanisms. Hence, the uptake and tissue distribution of bilberry anthocyanin after oral administration were further studied in rats.
