in vivo Staining of Fat in Tumor Bearing Mice by Benzo[a]phenoxazine Dyes. ∗

Summary

(1) S-phenylamino-9-dialkyl-aminobenzo[a]phenoxazine dyes stained fat in vivo when administered to mice in their food. (2) The fat staining properties of the dyes were not materially altered by substituents on the phenyl nucleus other than those of highly acidic nature, or by substitutions of the naphthyl group and certain nitrogen heterocyclic rings for the phenyl group. The 5-phenylamino-9-morpholinyl derivatives also stained fat in vivo. (3) S-benzylamino-9-di-methylamino- and diethylaminobenzo[a]phenoxazine dyes did not stain fat in vivo, al-though they did stain tumor tissue. The corresponding dyes in which the alkyl group on the 9-nitrogen contained more than 2 carbon atoms stained fat in vivo. These dyes also stained tumor tissue in vivo.