M-Hydroxyphenylhydracrylic acid

The normal daily excretion of m-hydroxyhippuric acid by man ranges from 2 to 150 mg, most subjects eliminating 4-6 mg (A15). The excretion of m-hydroxyphenylhydracrylic acid ranges from 2 to 150 mg (All), whereas the values found for m-hydroxybenzoic acid are, respectively, 8.8 mg in human males and 15.0 mg in females (B31), or 10-16 mg (T22). 

Although the presence of 3-hydroxyphenyl acids had been detected previously in urine, a widespread occurrence of such compounds had not been suspected before the work of Armstrong et al. (A12, A15). These acids probably arise from precursors found in the diet, as is shown by the influence of prolonged administration of chemically well-defined diets (A12), as well as by the big increase in the elimination of m-hydroxyhippuric and m-hydroxyphenylhydracrylic acids after ingestion of coffee (B22, S14). 

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