Synthesis, antimicrobial, anti-inflammatory, antioxidant and cytotoxicity of new pyrimidine and pyrimidopyrimidine derivatives

Abstract

A series of novel pyrimidine and pyrimidopyrimidine analogs were synthesized in good yield from 6-amino-4-aryl-2-oxo-pyrimidine-5-carbonitrile (1a-d). The synthesized compounds were characterized using various spectral studies, including FT-IR, ¹H NMR, ¹³C NMR, mass spectrometry, and elemental analysis. Newly synthesized pyrimidopyrimidines and 2-(substituted-pyrazolyl)pyrimidine derivatives were assessed in vitro for their cytotoxic activities against three cancerous cell lines: colorectal carcinoma (HCT-116), mammary gland breast cancer (MCF-7), and hepatocellular carcinoma (HEPG-2), as well as normal fibroblasts (W138). The results indicated that compounds 3b, 10b, and 10c exhibited the highest cytotoxic activities, with IC₅₀ values very close to those of the reference drug (doxorubicin) across all studied cancerous cell lines, while also demonstrating good safety effects on the normal human lung fibroblast cell line. Furthermore, all the synthesized compounds were examined for their antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), one Gram negative bacterium (Escherichia coli) and two fungal species (Candida albicans and Aspergillus flavus). The antimicrobial results of the synthesized compounds, when compared with the reference drugs ampicillin and clotrimazole, revealed that compounds 3a, 3b, 3d, 4a-d, 9c and 10b exhibited excellent antimicrobial activities. Moreover, membrane stabilization or anti-hemolytic activity was employed as a method to study the in vitro anti-inflammatory activity of the prepared heterocyclic compounds. Antioxidant activities were also assessed by measuring the percentage of free radical scavenging. Compounds 4b, 10c and 11a-c demonstrated strong anti-hemolytic and antioxidant effects, which can be attributed to their ability to protect red blood cells from hemolysis.

Fig. 1

Synthesis of compounds 1a-d, 2a-d. Reagents and conditions: (a) Potassium carbonate (0.1 mol), abs. EtOH (100 ml), reflux, 24 h. (b) POCl₃ (20 ml), reflux, 3 h.

Fig. 2

Synthesis of compounds 3a-d to 9a-d. Reagents and conditions: (a) Acetic anhydride (10 ml), acetic acid (10 ml), conc. H₂SO₄ (2 drops), reflux, 20 h. (b) Hydrazine hydrate (5 ml), abs. EtOH (20 ml), reflux, 3 h. (c) Ethanol amine (5 ml), abs. EtOH (20 ml), reflux, 3 h. (d) Methyl amine (5 ml), abs. EtOH (20 ml), reflux, 3 h. (e) Dimethyl amine (5 ml), abs. EtOH (20 ml), reflux, 3 h. (f) Ethyl amine (5 ml), abs. EtOH (20 ml), reflux, 3 h. (g) Morpholine (5 ml), abs. EtOH (20 ml), reflux, 3 h.

Fig. 3

Synthesis of compounds 10a-c, 11a-c. Reagents and conditions: (a) Malononitrile (0.79 g, 0.012 mol), abs. EtOH (20 ml), reflux, 3 h. (b) Acetyl acetone (1.2 g, 0.012 mol), abs. EtOH (20 ml), two drops of conc. HCl, reflux, 3 h.

Fig. 4

Cytotoxic effects of the synthesized compounds on the tested cell lines.