IN-SITU INTESTINAL-ABSORPTION OF 2-O-ALPHA-D-GLUCOPYRANOSYL-L-ASCORBIC ACID IN GUINEA-PIGS

The intestinal absorption efficacy of 2-O-alpha-D-glucopyranosyl-L-asc orbic acid (AA-2G), which has been recently synthesized and characteri zed as a stable ascorbate (AsA), was determined in guinea pigs by the perfusion technique. Perfusion of AA-2G in isotonic phosphate buffer t o the small intestine resulted in a decrease of AA-2G accompanied by a n increase of AsA in the perfusate. The results showed that intact AA- 2G was not detected in the plasma of the portal vein of guinea pigs at 2 h after perfusion. The disappearance of AA-2G from perfusate was co mpletely inhibited by the addition of castanospermine, a specific alph a-glucosidase inhibitor, or by carbohydrates such as maltose. These re sults indicate that ascorbic acid released from AA-2G by alpha-glucosi dase on the brush border membrane is effectively taken up across the i ntestinal ascorbate transport channels, into a serosal site, whereas A A-2G permeation was poor via the passive transport system.