Lipid separation from Urtica dioica: Existence of platelet-activating factor

The common wild plant nettle, especially Urtica dioica, is one of the most potent plants in producing direct irritation to the skin (urticaria). In this study, total lipids of Urtica dioica were separated into neutral and polar lipids, which were further fractionated by high-performance liquid chromatography(HPLC). Triglycerides, sterol-esters, fatty acids, fatty acid methyl esters, glyceryl ethers, sterols, tocopherols, diglycerides, and galactosyldiglycerides were identified as the main neutral lipid classes by comparing their retention times on an HPLC column and their migration following spraying with specific reagents on thin-layer chromatography (TLC) with standards. Four main classes of phospholipids (i.e., phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine, and lysophosphatidylcholine) were also identified. A phospholipid that induced platelet aggregation was identified as platelet-activating factor on the basis of biological, chemical, and spectral methods.