What is D-Glucaric acid?

D-Glucaric acid, otherwise known as saccharic acid, is the product of oxidizing sugars or polysaccharides with nitric acid. German chemist Heinrich Kiliani described the reaction in 1925. Kiliani is better known for collaborating with Emil Fischer on a method for adding a carbon atom to a saccharide chain while preserving the sugar’s stereochemistry.

Application

D-Glucaric acid is a naturally occurring aldaric acid, typically found in small amounts in a variety of fruits and vegetables. Potential commercial applications for d-glucaric acid include use as a metal sequestering agent, retarding agent for metallic mordants in the dyeing of textiles, and corrosion inhibitor for metals. A current commercial use of a salt form of d-glucaric acid as a dietary supplement claimed to help maintain healthy cholesterol levels and prevent cancer. As a dietary supplement, d-glucaric acid functions as a precursor to the β-glucuronidase inhibitor and d-glucaro-1,4-lactone. In addition to these end uses, d-glucaric acid is the starting material for the synthesis of other chemicals, particularly as a diacid monomer used to make a number of polyhydroxypolyamides.

Metabolism

D-glucaric acid is a natural non-toxic compound produced in small amounts by mammals, including humans. In mammals, D-glucaric acid and D-glucaro-l,4-lactone are end-products of the D-glucuronic acid pathway. The enzyme D-glucuronolactone dehydrogenase has been found to be responsible for the oxidation of the lactone of D-glucuronic acid to D-glucaro-l,4;6,3-dilactone. This dilactone hydrolyzes spontaneously in aqueous solution to D-glucaro-l,4-lactone, a potent beta-glucuronidase inhibitor. 

D-glucaric acid is also found in many fruits and vegetables, with the highest concentrations found in grapefruits, apples, oranges, and cruciferous vegetables. b-glucuronidase is present in the circulation and probably all vertebrate tissues and is capable of hydrolyzing glucuronide conjugates. This enzyme is also produced by colonic microflora. Elevated b-glucuronidase activity is associated with an increased risk for various cancers, particularly hormone-dependent cancers such as breast and prostate cancer. 

D-glucaro-l,4-lactone increases detoxification of carcinogens and tumor promoters by inhibiting b-glucuronidase and preventing the hydrolysis of their glucuronides. D-glucaro-l,4-lactone was found to be formed from supplemented D-glucarate salt in the stomach and it is absorbed from the intestinal track, transported with the blood to different internal organs, and excreted in urine and, to a lesser extent, in bile. D-glucaro-l,4-lactone and its precursors exert their anticancer action in part through alterations in steroidogenesis accompanied by changes in the hormonal environment and proliferative status of the target organs. 

D-glucarates not only suppress cell proliferation and inflammation, but also induce apoptosis. By supplementing D-glucarates, one can favor the body's natural defense mechanism for eliminating carcinogens and tumor promoters and their effects.