Synthesis of diethanolamides of N‐lauroyl dipeptides and correlation of their structures with surfactant and antibacterial properties

Abstract

Diethanolamides (DEA) of proteins possess nonionic skin‐compatible, biodegradable, surfactant and antibacterial properties. The DEA of dipeptides are, however, too hydrophilic to be effective surfactants. Hence, DEA of N‐lauroyl dipeptides were synthesized and their surfactant and antibacterial properties were correlated with the structures of amino acid moieties. N‐Lauroyl condensates of five simple amino acids were coupled with the corresponding amino acid methyl esters and the resulting products were condensed with diethanolamine in the presence of sodium methoxide to yield DEA of N‐lauroyl dipeptides. The DEA of N‐lauroyl glycine dipeptide showed surfactant properties comparable to lauroyl diethanolamide. The thiol group in the cysteine derivative exerted an unfavorable effect on surfactant properties. The isobutyl side chain in the leucine derivative contributed greatly to the antibacterial activity when compared to the other amino acid derivatives studied.