Kristina Pavić

Design, synthesis and biological evaluation of novel primaquine-cinnamic acid conjugates of the amide and acylsemicarbazide type

In this paper design and synthesis of a scaffold comprising primaquine (PQ) motif and cinnamic acid derivatives (CADs) bound directly (compounds 3a–k) or via a spacer (compounds 7a–k) are reported. In the first series of compounds, PQ and various CADs were connected by amide bonds and in the second series by acylsemicarbazide functional groups built from the PQ amino group, CONHNH spacer and the carbonyl group originating from the CADs. PQ-CAD amides 3a–k were prepared by a simple one-step condensation reaction of PQ with a series of CAD chlorides (method A) or benzotriazolides 2 (method B). The synthesis of acylsemicarbazides 7a–k included activation of PQ with benzotriazole, preparation of PQ-semicarbazide 6 and its condensation with CAD chlorides 4. All synthesized PQ-CAD conjugates were evaluated for their anticancer, antiviral and antioxidative activities. Almost all compounds from series 3 were selective towards the MCF-7 cell line and active at micromolar concentrations. The o-fluoro derivative 3h showed high activity against HeLa, MCF-7 and in particular against the SW 620 cell line, while acylsemicarbazide 7f with a benzodioxole ring and 7c, 7g and especially 7j with methoxy-, chloro- or trifluoromethyl-substituents in the para position showed high selectivity and high inhibitory activity against MCF-7 cell line at micromolar (7c, 7f, 7g) and nanomolar (7j) levels. Acylsemicarbazide derivatives with trifluoromethyl group(s) 7i, 7j and 7k showed specific activity against human coronavirus (229E) at concentrations which did not alter the normal cell morphology. The same compounds exerted the most potent reducing activity in the DPPH test, together with 7d and 7g, while methoxy (compounds 7c–e), benzodioxole (7f), p-Cl (7g) and m-CF3 (7i) acylsemicarbazides and amide 3f presented the highest LP inhibition (83%–89%). The dimethoxy derivative 7d was the most potent LOX inhibitor (IC50 = 10 μΜ). The performed biological tests gave evidence of acylsemicarbazide functional group as superior binding group in PQ-CAD conjugates.

Insights into biological activity of ureidoamides with primaquine and amino acid moieties

Abstract Primaquine (PQ) ureidoamides 5a–f were screened for antimicrobial, biofilm eradication and antioxidative activities. Susceptibility of the tested microbial species towards tested compounds showed species- and compound-dependent activity. N-(diphenylmethyl)-2-[({4-[(6-methoxyquinolin-8-yl)amino]pentyl}carbamoyl)amino]-4-methylpentanamide (5a) and 2-(4-chlorophenyl)-N-(diphenylmethyl)-2-[({4-[(6-methoxyquinolin-8-yl)amino]pentyl}carbamoyl)amino]acetamide (5d) showed antibacterial activity against S. aureus strains (MIC = 6.5 µg/ml). Further, compounds 5c and 5d had weak antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. None of the tested compounds showed a wide spectrum of antifungal activity. In contrast, most of the compounds exerted strong activity in a biofilm eradication assay against E. coli, P. aeruginosa and Candida albicans, comparable to or even higher than gentamycin, amphotericin B or parent PQ. The most active compounds were 5a and 5b. Tested compounds were inactive against biofilm formation by C. parapsylosis, Enterococcus faecalis, C. tropicalis and C. krusei. Compounds 5b–f significantly inhibited lipid peroxidation (80–99%), whereas compound 5c presented interesting LOX inhibition.

Insights into the mechanism of antiproliferative effects of primaquine-cinnamic acid conjugates on MCF-7 cells

Abstract In our previous paper, we showed that three primaquine-cinnamic acid conjugates composed of primaquine (PQ) residue and cinnamic acid derivatives (CADs) bound directly by an amide linkage (1) or through an acylsemicarbazide spacer (2 and 3) had significant growth inhibitory effects on some cancer cell lines. Compound 1 induced significant growth inhibition in the colorectal adenocarcinoma (SW620), human breast adenocarcinoma (MCF-7) and cervical carcinoma (HeLa) cell lines, while compounds 2 and 3 selectively inhibited the growth of MCF-7 cells. To better understand the underlying mechanisms of action of these PQ-CADs, morphological studies of the effects of test compounds on MCF-7 cells were undertaken using haematoxylin and eosin stain. Further analysis to determine the effects of test compounds on caspase activity and on the levels of apoptosis proteins were undertaken using the enzyme-linked immunosorbent assay (ELISA). Haematoxylin and eosin staining revealed that compounds 1 and 3 induced morphological changes in MCF-7 cells characteristic of apoptosis, while 2-treated cells were in interphase. Cell cycle analysis showed that cells treated with 1 and 3 were in sub-G1, while cells treated with 2 were mainly in interphase (G1 phase). Further, the study showed that the treatment of MCF-7 cells with 1 and 3 resulted in poly ADP ribose polymerase (PARP) cleavage as well as caspase-9 activation, indicating that they induced apoptotic cell death. We further investigated their effects on two important processes during metastasis, namely, migration and invasion. Compounds 1 and 3 inhibited the migration and invasion of MCF-7 cells, while compound 2 had a marginal effect.