Nonideal behavior of alkoxyphenoxazone compounds (cytochrome P-450 substrates) in aqueous solution.
Rabovsky-J; Heflin-E; Judy-DJ; Sapola-NA
J Biochem Toxicol 1989 Summer; 4(2):127-132
The spectral properties of alkoxyphenoxazone compounds in organic and aqueous solutions were studied. Solutions of methoxyphenoxazone (MeOPx), ethoxyphenoxazone, pentoxyphenoxazone (PeOPx) and benzyloxyphenoxazone, ranging from 0.4 millimolar (mM) to 2mM were prepared in 2% methylsulfoxide. Spectral properties were measured in absolute ethanol (EtOH) or an aqueous solvent (HEPES). In EtOH, each compound exhibited a peak at 460 nanometers (nm) and a shoulder at 390nm and the Lambert/Beer law was obeyed. In HEPES, only MeOPx obeyed the Lambert/Beer law; peak absorption spectra for the other three compounds were shifted to lower wavelengths and the extinction coefficients decreased with increasing concentrations. These changes were dependent on the side chains. The blue shift and extinction coefficients seen at high PeOPx concentrations in HEPES changed with temperature. Resorufin and phenoxazone obeyed the Lambert/Beer law in both EtOH and HEPES. The authors conclude that spectral data obtained from aqueous solutions of alkoxyphenoxazone compounds may be unreliable.
NIOSH-Author; Aromatic-hydrocarbons; Analytical-methods; Chemical-properties; Spectrographic-analysis; Aqueous-solutions; Chemical-structure; Analytical-chemistry;
Author Keywords: Alkoxyphenoxazone; Cytochrome P-450; Spectral Properties
Journal of Biochemical Toxicology