Formation of a vitamin C conjugate of acrolein and its paraoxonase-mediated conversion into 5,6,7,8-tetrahydroxy-4-oxooctanal.

Vitamin C (ascorbic acid) has been reported to participate in Michael addition reactions in vitro to form vitamin C conjugates with alpha,beta-unsaturated aldehydes, such as acrolein. This study shows evidence for the formation and metabolism of the vitamin C conjugate of acrolein (AscACR) in cultured human monocytic THP-1 cells exposed to acrolein diacetate. By using (18)O and (13)C labeling in combination with liquid chromatography-tandem mass spectrometry, AscACR was shown to undergo hydrolytic conversion of the ascorbyl lactone into an intermediate carboxylic acid.

Covalent interaction of ascorbic acid with natural products.

While ascorbic acid (vitamin C) is mostly known as a cofactor for proline hydroxylase and as a biological antioxidant, it also forms covalent bonds with natural products which we here refer to as 'ascorbylation'. A number of natural products containing an ascorbate moiety has been isolated and characterized from a variety of biological sources, ranging from marine algae to flowering plants. Most of these compounds are formed either as a result of nucleophilic substitution or addition by ascorbate, e.