Intestine, release

About ten percent of the calories contained in the Western diet are supplied by fructose (approximately fifty g/day). The major source of fructose is the disaccharide sucrose, which, when cleaved in the intestine, releases equimolar amounts of fructose and glucose (see p. 86). Fructose is also found as a free monosaccharide in high-fructose corn syrup (55 percent fructose/45 percent glucose, which is used to sweeten most cola drinks), in many fruits, and in honey. Entry of fructose into cells is not insulin-dependent (unlike that of glucose into certain tissues, see p. 95), and, in contrast to glucose, fructose does not promote the secretion of insulin. 

Andreasen MF, Kroon PA, Williamson G, Garcia-Conesa MT. 2001b. Intestinal release and uptake of phenolic antioxidant diferulic acids. Free Radio Biol Med 31 304-314. 

Figure 10.4 Enterohepatic circulation (as indicated by ). Polar xenobiotic conjugates are secreted into the intestine via the bile duct and gall bladder. Conjugates are hydrolyzed in the intestines, released xenobiotics are reabsorbed, and transported back to the liver via the portal vein.

Anal, A. K., Bhopatkar, D., Tokura, S.,Tamura, H., and Stevens, W. F. (2003), Chitosan-alginate multilayer beads for gastric passage and controlled intestinal release of protein, Drug Dev. Ind. Pharm., 29,713-724. 

The hydrolysis of maltitol in the small intestine releases sorbitol and glucose. Glucose is actively transported and rapidly absorbed, whereas sorbitol absorption is passive. The nonabsorbed sorbitol and nonhydrolyzed maltitol are fermented by the microflora in the colon. The relative importance of... 

Kato T, Read R, Rozga J, et al. 1992. Evidence for intestinal release of absorbed selenium in a form with high hepatic extraction. Am J Physiol 262(5Ptl) G854-858. 

The snlfonamides are structurally related to p-aminoben-zoic acid. The presence of a free p-amino gronp is essential for the antibacterial action. Succinylsulfathiazole (sulfasuxi-dine) and phthalysnlfathiazole (sulfathalidine) are agents with a snbstitnted p-amino group. These intestinal antiseptics are slowly hydrolyzed in the intestine, releasing sulfathiazole, which exerts antiseptic effects against the coliform and clostridial organisms. 

The sulphonamides have been used in the treatment of intestinal infections. Substitution of the aniline N with a succinyl group produces an acidic compound which is fully ionised at intestinal pH and is therefore not appreciably absorbed into the bloodstream. Slow enzjmatic hydrolysis of the product in the intestine releases the free primary amine group which is essential for activity. This concept of prodmg design has been exploited in the sjmthesis of succinyl-sulfathiazole (p/Gt 4.5) from sulfathiazole (p/Gt 7.1) (Fig. 22.42). 

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