Synthesis of spin-labeled neutral lipids: Nitroxyl derivatives of triglycerides and sterol esters

Methods for the preparation of useful spin-labeled neutral lipids are described. A spin-labeled triglyceride has been prepared by acylation of 1,3-distearoylglycerol with stearic acid anhydride bearing the 4′,4′-dimethyloxazolidine-N-oxyl ring at carbon-12. The same fatty acid anhydride has been used to acylate the 3-hydroxy group of cholesterol to obtain a cholesteryl ester with the nitroxyl function in the fatty acyl chain. The 4′,4′-dimethyloxazolidinyl-1-oxyl derivative of 5α-an drostan-3-one-17β-ol has been esterified with stearic acid anhydride to obtain a steroid ester with the paramagnetic center in the steroid nucleus.