The novel primaquine derivatives of N-alkyl, cycloalkyl or aryl urea: synthesis, cytostatic and antiviral activity evaluations

Primaquine, N4-(6-methoxy-8-quinolinyl)-1, 4-pentanediamine, is known antimalarial drug that is active against both the latent liver forms of the relapsing malaria caused by Plasmodium vivax and Plasmodium ovale and the gametocytes from all species of parasite causing human malaria, including chloroquine-resistant Plasmodium falciparum. The novel urea primaquine derivatives 3a-i were prepared by aminolysis of benzotriazolide 2 with the corresponding amine in the presence or absence of triethylamine. In order to obtain the targeted derivatives of urea 3a-i with different lipophilicity, various aliphatic and aromatic primary or secondary amines were used for their synthesis (diethylamine, cyclopentylamine, cyclohexylamine, cyclohexanemethylamine, dicyclohexylamine, 2-phenylethylamine, 4-(aminomethyl)pyridine and benzhydrylamine). Compound 2 was prepared by acylation of primaquine with 1-benzotriazole carboxylic acid chloride. Among all compounds evaluated, the pyridine derivative 3h exhibited the best cytostatic activities against colon carcinoma, human T-lymphocyte and murine leukemia. However, this compound showed also rather marked cytotoxicity towards human normal fibroblasts. The highest selectivity in the inhibitory effects on human malignant tumour cell lines vs. normal fibroblasts was found for ureas 3c, 3d and 3g. Results of broad antiviral evaluation showed that pyridine and phenethyl derivatives of urea 3h and 3g exhibited some selective inhibition against cytomegalovirus.