Heat Deterioration of Phospholipids. III. Thermally Deteriorated Products from Phosphatidylethanolamine and Hexose

Abstract

Novel four 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives were obtained with increase of UV absorption at 350 nm and browning of the solution by heating paste lecithin from soybean (SL) in octane. These four derivatives were characterized the factor based on UV absorption at 350 nm. The SL was separated into the hexane (DSSL fr.) and 60% ethanol in water frs. by liquid- liquid partition method. Even when the DSSL fr. was heated in octane more than 9 h, the four derivatives were not formed and increase of any UV absorption was also not observed but the solution color was slightly yellowing. On the other hand, the formation of four derivatives and increase of UV absorption at 350 nm were observed when DSSL and 60% ethanol in water frs. were combined and, then, heated in octane. From the 60% ethanol in water fr, sucrose, raffinose and stachyose were isolated and identified as compounds which involved the formation of the derivatives with the DSSL fr. When DSPE (1,2-di-O-stearoyl-sn-glycero-3-phosphatidylethanolamine) and any hexose were combined and then heated, two 2,3-dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives generated with increase of UV absorption at 350 nm and browning. From these results, it is concluded that the formation of derivatives, with increase of the UV absorption at 350 nm and browning, are based on the reaction of sugars and phosphatidylethanolamine (PE) in SL.