Urinary Simple Phenols in Rats Fed Diets Containing Different Amounts of Casein and 10% Tyrosine

Abstract

Gas chromatographic analysis of extracts of hydrolyzed urines demonstrated a lower excretion of p-cresol (P < 0.01) and phenol (P < 0.05) in rats fed a “protein-free” diet compared with those fed 10, 20, 40 and 64% casein. The quantities of these compounds in the urine were not significantly different when rats were fed high casein diets (40 and 64%) or a diet containing 20% casein. The simple phenols excreted by rats fed a 10% tyrosine diet were analyzed by thin-layer and gas chromatography. The amounts recovered from the urines far exceed the values for urinary “volatile phenols” reported by earlier investigators. p-Cresol accounted for the bulk of the simple phenols found in these urines, but smaller amounts of phenol, hydroquinone, 4-methylcatechol and 4-methylguaiacol were also present. It is concluded that the formation of simple phenols is probably of considerable significance in regard to the adverse effects observed during long-term feeding of high tyrosine diets.