A new amino acid derivative of ursodeoxycholate, (N-L-Glutamyl)-UDCA (UDCA-Glu), to selectively release UDCA in the colon.

BACKGROUND: Ursodeoxycholic acid (UDCA) is chemoprotective in animal models of colon cancer but results from clinical trials have been less impressive probably because UDCA is rapidly absorbed in the small intestine and little reaches the colon. UDCA-glutamate (Glu), a novel bile acid, was synthesized with the objective of utilizing peptide bond cleavage by brush border enzymes to enhance delivery of UDCA to the colon. MATERIALS AND METHODS: Qualitative and quantitative intestinal intraluminal and fecal bile acid composition measured by mass spectrometry was determined in Fisher rats after intragastric administration of UDCA, or UDCA-Glu for 5 days. The effect of UDCA and UDCA-Glu on bile flow was studied after bile duct canulation. RESULTS: In the small intestine, UDCA was found in higher amounts when UDCA was administered compared with UDCA-Glu (1.50 + or - 0.32 vs. 0.75 + or - 0.12 mg). By contrast, UDCA-Glu administration resulted in a greater delivery of UDCA to the colon. The fecal bile acid composition resembled that of the intraluminal colonic composition and a higher mass of UDCA (unconjugated 3.39 + or - 0.30 mg; conjugated 6.40 + or - 1.03 mg) was found in rats treated with UDCA-Glu compared to those treated with UDCA (2.27 + or - 0.11 and. 0.04 + or - 0.01 mg, respectively), establishing increased delivery of UDCA to the colon. Both bile acids similarly increased bile flow but the initial effect of UDCA was greater than that of UDCA-Glu. CONCLUSION: Conjugation of UDCA to glutamic acid reduces its intestinal absorption and biotransformation resulting in increased colonic delivery of UDCA. UDCA-Glu may have potential application as a pro-drug for enhancing the action of UDCA in the treatment of colonic diseases.

3alpha-6alpha-Dihydroxy-7alpha-fluoro-5beta-cholanoate (UPF-680), physicochemical and physiological properties of a new fluorinated bile acid that prevents 17alpha-ethynyl-estradiol-induced cholestasis in rats.

3alpha-6alpha-Dihydroxy-7alpha-fluoro-5beta-cholanoate (UPF-680), the 7alpha-fluorine analog of hyodeoxycholic acid (HDCA), was synthesized to improve bioavailability and stability of ursodeoxycholic acid (UDCA). Acute rat biliary fistula and chronic cholestasis induced by 17alpha-ethynyl-estradiol (17EE) models were used to study and compare the effects of UPF-680 (dose range 0.6-6.0 micromol/kg min) with UDCA on bile flow, biliary bicarbonate (HCO(3)(-)), lipid output, biliary bile acid composition, hepatic enzymes and organic anion pumps. In acute infusion, UPF-680 increased bile flow in a dose-related manner, by up to 40.9%. Biliary HCO(3)(-) output was similarly increased. Changes were observed in phospholipid secretion only at the highest doses. Treatment with UDCA and UPF-680 reversed chronic cholestasis induced by 17EE; in this model, UDCA had no effect on bile flow in contrast to UPF-680, which significantly increased bile flow. With acute administration of UPF-680, the biliary bile acid pool became enriched with unconjugated and conjugated UPF-680 (71.7%) at the expense of endogenous cholic acid and muricholic isomers. With chronic administration of UPF-680 or UDCA, the main biliary bile acids were tauro conjugates, but modification of biliary bile acid pool was greater with UPF-680. UPF-680 increased the mRNA for cytochrome P450 7A1 (CYP7A1) and cytochrome P450 8B (CYP8B). Both UDCA and UPF-680 increased the mRNA for Na(+) taurocholate co-transporting polypeptide (NCTP). In conclusion, UPF-680 prevented 17EE-induced cholestasis and enriched the biliary bile acid pool with less detergent and cytotoxic bile acids. This novel fluorinated bile acid may have potential in the treatment of cholestatic liver disease.