title: Synthesis and anti-melanoma activity of analogues of N-acetyl-4-S-cysteaminylphenol substituted with two methyl groups alpha to the nitrogen.
abstract: N-Acetyl-4-S-cysteaminylphenol 1 is an analogue of a biosynthetic intermediate in the pathway to melanin. It is probably oxidized to an o-quinone which can alkylate cellular nucleophiles resulting in interference with cell growth and proliferation. It is reported to have useful anti-melanoma activity. We previously synthesized a range of analogues of 1 by varying the acyl portion of the amide. A modest increase in melanoma activity against six melanoma cell lines for these analogues could be correlated with increased lipophilicity. Thirteen new analogues of 1 containing two methyl groups at the alpha-position of the amino component and various acyl groups have now been prepared and assessed for anti-melanoma activity against six human melanoma cell lines. Most of the new compounds displayed greater cytotoxicity than the lead compound 1. The highest cytotoxicity against the cell lines was observed for the cyclohexylacetamide 11 followed by the cyclohexylcarboxamide 10 and the 2,2-dimethylpropanamide 6. The IC50 values of the most cytotoxic compound 11 against the cell lines were comparable with those of cisplatin. Small variations in the acyl components of these analogues, such as reducing the ring size, lengthening the carbon chain and reducing the amount of chain branching, resulted in a considerable loss of cytotoxicity. The moderate activity of 6, 10 and 11 against SK-Mel-24 cells (non-tyrosinase containing) and an ovarian cell line suggests that interference with the melanin pathway may not be their only mode of action.
authors.affiliation: Department of Chemistry, University of Glasgow, UK.
authors.forename: N J
authors.initials: NJ
authors.lastname: Lant
authors.forename: P
authors.initials: P
authors.lastname: McKeown
authors.forename: M C
authors.initials: MC
authors.lastname: Timoney
authors.forename: L R
authors.initials: LR
authors.lastname: Kelland
authors.forename: P M
authors.initials: PM
authors.lastname: Rogers
authors.forename: D J
authors.initials: DJ
authors.lastname: Robins
mesh_terms: D000970:Antineoplastic Agents / Q000138:chemical synthesis* / Q000494:pharmacology*; D003543:Cysteamine / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000494:pharmacology*; D004354:Drug Screening Assays, Antitumor; D005260:Female; D006801:Humans; D007202:Indicators and Reagents; D008546:Melanoma, Experimental / Q000188:drug therapy*; D010051:Ovarian Neoplasms / Q000188:drug therapy; D010636:Phenols / Q000138:chemical synthesis* / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014407:Tumor Cells, Cultured
chemical_list: D000970:Antineoplastic Agents; D007202:Indicators and Reagents; D010636:Phenols; D003543:Cysteamine; C066420:N-acetyl-4-S-cysteaminylphenol