Complexation of bile acids with 2-hydroxypropyl-β-cyclodextrin: A 13C-NMR study

Abstract The interaction of chenodeoxycholic acid (3α,7α-dihydroxy-5β-cholan-24-oic acid) 1; cholic acid (3α,7α,12α-trihydroxy-5β-cholan-24-oic acid) 2, deoxycholic acid (3α,12α-dihydroxy-5β-cholan-24-oic acid) 3 and ursodeoxycholic acid (3α,7β-dihydroxy-5β-cholan-24-oic acid) 4 with 2-hydroxypropyl-β-cyclodextrin HPβCD (partially functionalized) is studied by measuring the changes in 13C-NMR chemical shifts induced by complexation in methanol-d4. The alkyl chain of the bile acids enters the cyclodextrin cavity. The interaction of 1 and 4 with HPβCD is stronger, in this solvent, with respect that of 2 and 3.