Linear pentapeptide ester, phthaloyl-bis-[glycylglycine]-OMe, 3, have been prepared via coupling of N-phthalic acid or dichloride with glycylglycine ester, which was hydrolyzed to the corresponding acid, phthaloyl-bis-[glycylglycine], 4. Cyclization of tetrapeptide acids to give cyclic pentapeptide esters, acids and hydrazides. A preliminary cytotoxicity evaluation (National Cancer Institute, Cairo, EGYPT), for a representative example, Cyclo-(phthaloyl)-)-bis-[glycylglycine]-L-Lys-OMe (phthaloyl cyclic pentapeptide methyl ester) 5, against ...
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