Anthocyanins are efficiently absorbed from the small intestine in rats

Abstract

Anthocyanins are natural pigments that possess antioxidant activities and are implicated in various health effects. Recent studies showed that the stomach is a site of anthocyanin absorption. However, the fate of anthocyanins in the small intestine remains unknown. We therefore investigated anthocyanin absorption after in situ perfusion of the jejunum + ileum in rats. The intestine was perfused for 45 min with a physiological buffer supplemented with various anthocyanins. Purified anthocyanin glycosides (9.2 nmol/min) or blackberry (9.0 nmol/min) or bilberry (45.2 nmol/min) anthocyanins were perfused. A high proportion of anthocyanin glycosides was absorbed through the small intestine after perfusion. The rate of absorption was influenced by the chemical structure of the anthocyanin and varied from 10.7 (malvidin 3-glucoside) to 22.4% (cyanidin 3-glucoside). Regardless of the anthocyanins perfused, only glycosides were recovered in the intestinal lumen. After perfusion of a high amount of blackberry anthocyanins (600 nmol/min), native cyanidin 3-glucoside was recovered in urine and plasma from the aorta and mesenteric vein. Methylated and/or glucuronidated derivatives were also identified. Analysis of bile samples revealed that cyanidin 3-glucoside and its methylated derivatives (peonidin 3-glucoside + peonidin glucuronide) quickly appeared in bile. This study demonstrated that anthocyanin glycosides are rapidly and efficiently absorbed from the small intestine. Furthermore, anthocyanins are quickly metabolized and excreted into bile and urine as intact glycosides as well as methylated forms and glucuronidated derivatives.