Biliary D-glucaric acid: its quantitation and preventive role in gallstone formation

A method for quantitation of D-glucaric acid in bile has been developed involving extraction with tetrahexylammonium chloride, boiling for 40-60 min, and determination of the percentage inhibition of beta-glucuronidase activity at 56 degrees C and pH 4. D-glucaric acid, bilirubin, bile acid, and protein were determined in 106 human gallbladder biles obtained at autopsy, including 20 with gallstones. The mean D-glucaric acid content was 1125 +/- 159 microM (mean +/- SE). Biliary beta-glucuronidase activity was not affected by D-glucaric acid because of 1) no difference in biliary D-glucaric acid content, either absolute or corrected for per unit of bilirubin, bile acid, or protein, between those with and those without gallstones; 2) no negative correlation between D-glucaric acid content and beta-glucuronidase activity in the bile; and 3) minimal conversion of D-glucaric acid to D-glucaro-1,4-lactone at the usual pH of bile. We conclude that biliary D-glucaric acid plays no role in the prevention of gallstone formation.