title: Efficiency of phenylpyruvic and phenyllactic acids as substitutes for phenylalanine in the diet of the growing rat.
abstract: Male weanling albino rats fed a diet containing all nutrients for optimal growth, including 45.4 mumoles of phenylalanine/g, gained weight at an average of 6.5 g/day. Removal of phenylalanine caused an average weight loss of 1.1 g/day. Addition of graduated increments of phenylalanine led to progressive increases in growth rate; the increases being proportional to the dietary content of this amino acid. When phenylpyruvic or L-phenyllactic acids were added isonitrogenously to the phenyl-alanine-free diet, growth rate also increased. Percent efficiency of these amino acid analogues as dietary substitutes for phenylalanine, calculated as (see article) varied from 50% to 70% for phenylpyruvic acid and 65% to 95% for L-phenyllactic acid. Efficiency increased as dose of analogue increased. Non-isonitrogenous substitution did not change growth rates. Supplementation with a megadose of pyridoxine did not increase the efficiency of phenylpyruvic acid. D-phenyllactic acid and cinnamic acid were completely ineffective as substitutes for phenylalanine. When tyrosine was withdrawn from the diet, efficiency of phenylpyruvic acid was 70% at several doses. The efficiency of L-phenyllactic acid was 65 to 40%, decreasing with increasing dose.
mesh_terms: D000818:Animals; D001555:Benzene Derivatives / Q000378:metabolism; D001835:Body Weight; D002934:Cinnamates / Q000627:therapeutic use; D004032:Diet; D004305:Dose-Response Relationship, Drug; D006128:Growth; D007773:Lactates / Q000378:metabolism*; D008297:Male; D009751:Nutritional Requirements; D010649:Phenylalanine / Q000378:metabolism / Q000627:therapeutic use; D010667:Phenylpyruvic Acids / Q000378:metabolism*; D011736:Pyridoxine / Q000494:pharmacology; D051381:Rats; D013237:Stereoisomerism; D014443:Tyrosine / Q000172:deficiency
chemical_list: D001555:Benzene Derivatives; D002934:Cinnamates; D007773:Lactates; D010667:Phenylpyruvic Acids; D014443:Tyrosine; D010649:Phenylalanine; D011736:Pyridoxine