Novel 1-acyl-4-substituted semicarbazide derivatives of primaquine - synthesis, cytostatic, antiviral and antioxidative studies.

A series of novel 1,4-substituted semicarbazides 5a-g with a primaquine moiety bridged by a carbonyl group at position 1 and a cycloalkyl, aryl, benzyloxy or hydroxy substituent at position 4 were prepared and biologically evaluated. The synthetic pathways applied for preparation of the title compounds involved benzotriazole as synthetic auxiliary. Primaquine semicarbazides 5a-g and their synthetic precursors benzotriazolecarbonyl semicarbazides 4 were evaluated for cytostatic, antiviral and antioxidative activities. All compounds of the series 5 showed high selectivity towards MCF-7 cells (breast carcinoma) with IC(50) values in the low micromolar range and the most active was benzyl derivative 5c (IC(50) 1 ± 0.2 µM). The benzhydryl derivative 5e showed significant cytostatic activities towards all the tested cell lines (IC(50) 4-18 µM). The same compound was the strongest lipoxygenase inhibitor as well (51%). The highest antioxidant activity was demonstrated for the hydroxy derivative 5g and benzotriazolecarbonyl semicarbazides 4b,c (61.2-68.5%). No antiviral activity was observed against a wide variety of DNA and RNA viruses.