In our paper, we established a new methodology to study the plasma concentration profile of anthocyanin and its metabolites in biological samples using individual rats that were tested both after intravenous and oral administration of anthocyanins.

Indeed, several new metabolites of anthocyanin were identified in our paper, so this article has given critical information for the field of in vivo functionality of anthocyanins. Further, this method is easy and useful for the determination of other active compounds derived from natural sources.

Anthocyanins are purple to reddish pigments found in flowering and edible plants such as blueberry, strawberry, and eggplant. Recently, the functionality of anthocyanins has been reported both in vivo and in vitro. One of the most famous functionalities of anthocyanins is the improvement of vision. Also, antioxidant and anticancer activities have been reported.

It is a critical issue to clarify in vivo behaviors such as absorption and metabolism not only in medicine but also in the functional compounds found in edible materials. However, studies on absorption and metabolism of anthocyanins are limited. So, in our reports, we focused our aims to clarify absorption and metabolism of cyanidin 3-glucoside (Cy3G)—a typical anthocyanin in colored fruits—after the oral administration of purified Cy3G in rats.

For this aim, we established highly sensitive methods for the detection of anthocyanins. Several metabolites have also been identified, indicating that these metabolites will contribute to the functionality of anthocyanin in vivo.

We were interested in the functionality of blueberry and its colored compounds. Indeed, anthocyanins have been reported to be major active components in many berry fruits. So, we focused our interest on their biological uptake and metabolism to clarify their in vivo functionality. To avoid encountering any major obstacles in our research, we developed the new methodology described above.

Our work is basically the result of collaboration with other researchers in Japan and in other countries as well. We believe that the results obtained in our report are beneficial for international society. We have already presented the results of this paper in several international symposiums, such as one recently conducted by the functional food division of the American Chemical Society.