DIETARY HYDROPEROXIDES OF LINOLEIC-ACID DECOMPOSE TO ALDEHYDES IN STOMACH BEFORE BEING ABSORBED INTO THE BODY

Our previous study (Biochim. Biophys. Acta 1393 (1998) 336-348, this i ssue) found that dietary hydroperoxides of trilinoleoylglycerol were b roken down, releasing linoleic acid hydroperoxides (LA-OOH) in the sto mach without reaching the intestines. The present paper describes the catabolic fate of LA-OOH in rat gastrointestines, in an attempt to elu cidate those products which can be absorbed into the body. At an intra gastric dose of 6.5 or 18 mu mol, LA-OOH was not transported to the in testines as determined by HPLC. At large doses (200 or 800 mu mol), mu ch greater than that in the daily diet, there was partial leakage of L A-OOH to the intestines. The periodical fate was analyzed with 17.2 mu mol [U-C-14]LA-OOH chemically and radiochemically. Exemplifying the p roduct composition at 30 min after treatment las percentage of dosed a mount), 27% unchanged LA-OOH, 9.7% epoxyketones, 3.5% hydroxyls (LA-OH ), 2.4% decomposed aldehydes, and 13% unknown products were found in t he gastric lumen. Another 25% was incorporated in the gastric tissue, and the other 6.4% occurred in the intestinal lumen and tissue as deco mposed aldehyde. The LA-OH further decomposed to aldehydes with time i n the stomach. When an aldehyde mixture was prepared and dosed, signif icant increases in hexanal and 4-hydroxynonenal were detected in the l iver 15 h later. These results show that the dietary LA-OOH is decompo sed to aldehydes in the stomach and that aldehydes are partly absorbed into the body. (C) 1998 Elsevier Science B.V. All rights reserved.