ABSTRACT
Anthocyanins are water soluble plant pigments responsible for the blue, purple, and red colors of many plant tissues. They occur primarily as O-glycosides of their respective aglycone anthocyanidin-chromophores. Although there are about 17 anthocyanidins found in nature, only six of them-cyanidin, delphinidin, petunidin, peonidin, pelargonidin, and malvidin-are ubiquitously distributed. The differences in chemical structure of these six common anthocyanidins occur at the 3′ and 5′ positions of the B-ring (Figure 3.1). Except for the 3-deoxyanthocyanidins such as luteolinidin and apigeninidin in sorghum (Figure 3.2) (Wu and Prior 2005b), the aglycones are rarely found in fresh plant materials. The sugar moiety is attached mainly at the 3-position on the C-ring or in some cases at the 5-, or 7-position on the A-ring. Glucose, galactose, arabinose, rhamnose, and xylose are the most common
3.1 Introduction .................................................................................................... 79 3.2 Intake and Bioavailability Estimates of Anthocyanins .................................. 82
3.2.1 Intake .................................................................................................. 82 3.2.2 Sites of Anthocyanin Absorption ....................................................... 82 3.2.3 In Vivo and In Vitro Bioavailability Estimates ................................... 83
3.3 Mechanisms of Absorption .............................................................................85 3.4 Factors Affecting Anthocyanin Absorption ...................................................86
