[2,4-Diisoleucine]-oxytocin. An analog of oxytocin with natriuretic and diuretic activities

[2,4-Diisoleucine]-oxytocin has been synthesized from the requisite protected nonapeptide intermediate which was prepared by the stepwise p-nitrophenyl ester method. In this analog of oxytocin, isoleucine residues replace the tyrosine and glutamine residues at the 2 and 4 positions of the hormone, and thus the isoleucine residue occurs successively at positions 2, 3, and 4. This compound possesses a very low level of avian vasodepressor, oxytocic, and pressor activities, and no antidiuretic activity. However, [2,4-diisoleucine]-oxytocin has a pronounced natriuretic activity and a mild diuretic effect.