Peptide sweeteners. 4. Hydroxy and methoxy substitution of the aromatic ring in L-aspartyl-L-phenylalanine methyl ester. Structure-taste relationships.

A series of analogues of the dipeptide sweetener L-aspartyl-L-phenylalanine methyl ester having hydroxy and/or methoxy substitution on the aromatic ring was synthesized and tasted. The introduction of a methoxy group in the para position of the aromatic ring of the peptide sweetener is crucial to the reduction or destruction of the sweet taste. The effects of substituents in the ortho or meta position are not as pronounced. In the case of o-methoxy substitution, the resulting analogue is only slightly less sweet than the parent dipeptide sweetener.