Phosphonic and phosphinic acid analogues of tyrosine and 3,4-dihydroxyphenylalanine (dopa) as potential antimelanotic agents.

Phosphonic acid and phosphinic acid analogues of tyrosine and 3,4-dihydroxyphenylalanine (dopa) were found to influence tyrosinase activity, thus being potential regulators of melanization in mammalian cells. The analogues were tested for their cytostatic activity in vitro, by means of total cell protein determination, on mouse B16 melanoma and, for comparison, on human KB carcinoma cell lines. Four compounds out of 22 revealed promising cytostatic activity for both cell lines, being nearly equipotent with dopa. Those compounds which most effectively suppressed the growth of both tumour cell lines were the same as those which had a significant influence on tyrosinase activity regardless of whether they acted as inhibitors or substrates.