R??? is an alkyl group having from about 7 to about 22, and preferably fom about 7 to about 16 carbon atoms, R???1 is an alkyl group having from about 1 to about 18, and preferably from about 8 to about 14 carbon atoms, R???2 is a substituent of a natural or synthetic I-amino acid, X??? is selected from the group consisting of alkali metal ions, alkaline earth metal ions, ammonium ions, and ammoni