Unique cholesteryl glucosides in Helicobacter pylori: Composition and structural analysis

A chloroform-methanol-extracted lipid of Helicobacter pylori was studied. Three kinds of glycolipids, accounting for about 25% (wt/wt) of the total lipid, were detected and identified to be cholesteryl glucosides. The structures of two of them were determined to be cholesteryl-α-D- glucopyranoside and cholesteryl-6-O-tetradecanoyl-α-D-glucopyranoside, and the plausible structure of the third one was identified as cholesteryl-6-O- phosphatidyl-α-D-glucopyranoside. Cholesteryl glucosides are very rare in animals and bacteria. Furthermore, those in H. pylori had an α-glycosidic linkage, which is rather unusual for natural glycosides, and a phosphate- linked cholesteryl glycoside like the cholesteryl-6-O-phosphatidyl-α-D- glucopyranoside has not been reported previously. As the cholesterol glucosides were detected in strains obtained from diverse geographical locations, the presence of cholesteryl glucosides in H. pylori is a very unique and a characteristic feature of the species. These findings add a new facet to the physiology and biochemistry, especially the cholesterol and glucose metabolism, of H. pylori. Furthermore, the cholesteryl glucosides of H. pylori showed hemolytic activities.