Anthocyanins are efficiently absorbed from the stomach in anesthetized rats

Abstract

After consumption, anthocyanins are rapidly absorbed as glycosides. Their rapid appearance in plasma could result from absorption through the gastric wall. The aim of this study was to evaluate the fate of anthocyanins in the stomach. Absorption of purified anthocyanins (14 micromol/L) as well as blackberry 14 and 750 micromol/L) and bilberry (88 micromol/L) anthocyanins was compared after in situ gastric administration for 30 min. A high proportion (approximately 25%) of anthocyanin monoglycosides (glucoside or galactoside) was absorbed from the stomach, whereas absorption of cyanidin 3-rutinoside was lower. Bilberry anthocyanins were also efficiently absorbed, but absorption varied greatly (19-37%) according to the anthocyanin structure; delphinidin glycosides were the most absorbed. When a high concentration of blackberry anthocyanins (750 micromol/L) was injected into the gastric lumen, the percentage of cyanidin 3-glucoside (Cy 3-glc) absorption was lower than after administration of a low concentration (14 micromol/L). After administration of this high concentration, blackberry anthocyanins were observed in plasma from gastric vein and aorta, whereas neither aglycones nor metabolites were detected. Analysis of bile samples revealed that Cy 3-glc appeared in bile after as little as 20 min. Peonidin 3-glucoside (the methylated form of Cy 3-glc) as well as unknown anthocyanin metabolites were also observed in bile. Thus, this study demonstrated that anthocyanin glycosides were quickly and efficiently absorbed from the stomach and rapidly excreted into bile as intact and metabolized forms.