Studies on the glycolipids of human saliva and gastric juice.

It has been reported that both human saliva and gastric juice (cf. Slomiany, B. L., and Slomiany, A. (1980) in Cell Surface Glycolipids (Sweeley, C. C., ed) American Chemical Society Symposium, No. 128, pp. 149-176, American Chemical Society, Washington, D.C.) contain substantial amounts of certain members of a series of novel glucoglycerolipids with a 1-O-alkyl glyceryl ether backbone. We have analyzed the glycolipids present in samples of saliva obtained from 10 individuals and in samples of gastric juice obtained from 5 individuals. In both fluids, compounds corresponding in the properties studied to standards of glucosyl- and lactosylceramides were found to be the major glycolipids. Other more complex glycosphingolipids were also present in smaller amounts. Human saliva was found to contain two glucoglycerolipids that were not detected in gastric juice. Analyses of these compounds indicated that they were mono- and diglucosyl diglycerides and were probably of bacterial origin. Methanolysis of the glycolipid fractions of saliva and gastric juice failed to reveal the presence of any more than traces of 1-O-alkyl glyceryl ethers. Our results do not exclude the possibility that glyceryl ether-containing glucoglycerolipids occur in human saliva and gastric juice. However, at most they would appear to be rather minor components of either fluid.