Assessment of intestinal absorption/metabolism of 3-chloro-1,2-propanediol (3-MCPD) and three 3-MCPD monoesters by Caco-2 cells

3-chloro-1,2-propanediol (3-MCPD) and 3-MCPD esters are contaminants present in a variety of processed foods, including infant formulas. Toxicological data are unavailable in humans, but rodent studies have demonstrated renal and testicular toxicity from 3-MCPD and 3-MCPD esters. There is evidence that 3-MCPD esters are hydrolyzed in the digestive system, releasing 3-MCPD that would be absorbed and induce damage. We assessed absorption and metabolism of 3-MCPD and three 3-MCPD monoesters, 1-oleoyl (1-Ol), 1-linoleoyl (1-Li) and 1-palmitoyl (1-Pa) commonly found in U.S. infant formula using differentiated Caco-2 cells. After 1-hour incubation, all three monoesters released free 3-MCPD and free fatty acids (FFA) into Caco-2 cell supernatants. Free 3-MCPD had a high apparent permeability (P-app = 30.36 +/- 1.31 cm/s x 10(-6)) suggesting that it is freely diffusible and highly absorbed by intestinal epithelium. 1-Li released 3-4-fold more 3-MCPD than 1-Ol and 1-Pa over 1 h, suggesting that this variable release rates might contribute to the overall in vivo exposure to 3-MCPD. None of the monoesters or FFA were detected in basolateral supernatants, suggesting that these compounds do not cross the intestinal wall without further transformation. In summary, this study provides relevant data to advance knowledge of in vivo intestinal absorption and metabolism of 3-MCPD monoesters.