Abstract
The formation of L-homocysteine sulfinic acid in the rat was examined in vivo and in vitro. This compound was rarely found, in trace amounts, in the urine and could not be detected in the tissues of various animal species studied. When L-homocysteine or methionine was given orally or intraperitoneally to rats deficient in vitamine B6, the level of homocysteine sulfinic acid in the urine increased and its synthesis could be detected in the liver.