DIPHENYLHYDANTOIN BINDING TO BRAIN LIPIDS AND PHOSPHOLIPIDS

Partition coefficients for diphenylhydantoin (DPH) were determined using 4 organic solvents and a 0.1 M phosphate buffer. Values ranged from 25.5 for chloroform to 0.02 for hexane. When chloroform-methanol-soluble [rabbit] brain lipids were added, there was a marked enhancement of DPH entry into hexane; 2 mg lipid resulted in an almost equal distribution between hexane and buffer. Proteolipids produced a similar but quantitatively small change. Neutral fat, cholesterol and glycolipids had no effect on DPH distribution. A number of commercially available phospholipids were tested and all increased the hexane/aqueous partition coefficient of DPH, although there was considerable variation among the several phospholipids employed. Neither total DPH concentration nor the addition of cations influenced this distribution. Strong evidence was provided for binding of DPH to phospholipids.