Preliminary biological studies of certain amino acid analogues

Among four amino acid analogues and their corresponding hydantoins prepared synthetically, two of the amino acids, 2-amino-2-methyl-5-hexenoic acid and 2-ethylphenylalanine, were found at moderately high concentrations to inhibit growth of Escherichia coli 9723 and the growth inhibition is prevented by methionine and phenylalanine, respectively. Mammalian studies showed no toxic effects in albino male mice, and the analogues were excreted unchanged primarily in the urine.