Synthesis and Antimicrobial Activity of Pyrimidine Salts with Chloranilic and Picric Acids

Pyrimidine salts such as 2-methyl-5-nitro-phenyl-(4-pyridin-3-yl-pyrimidin-2-yl)-amine (1) and 4-methyl-3-(4-pyridin-3-ylpyrimidin-2-yl-amino)-phenyl-amine (2) with chloranilic and picric acids were synthesized, and their in vitro antibacterial and antifungal activities were evaluated. e synthesized compounds were characterized by elemental analyses, UV-visible, FT-IR, and H NMR spectral studies. Compound 2a exhibited good inhibition towards antimicrobial activity compared to the other compounds.


Introduction
e health problem demands to search and synthesize a new class of antimicrobial compounds which are effective against pathogenic microorganisms and develop resistance to the antibiotics used in the current regime [1].e increasing resistance of human pathogens to current antimicrobial agents is a serious medical problem.During the 20th century, vaccines for bacterial toxins and many other common acute viral infections were developed and made widely available.e incidence of fungal infections has increased signi�cantly in the past two decades [2].e �rst-generation antifungal inhibitors of CYP51 have revolutionized the treatment of some serious fungal infections.
e pyrimidine derivatives possess a wide variety of potentially biological properties and are well known to work as herbicides [3,4] and pesticides [5].Pyrimidine derivatives have been found to exhibit cytostatic [6][7][8][9] immunomodulating [10,11] and antimicrobial properties [12][13][14][15].Imatinib is a new anticancer agent, and it is currently marketed by as Gleevec.It is a protein tyrosine kinase inhibitor that inhibits the Bcr-Abl tyrosine kinase, the constitutive abnormal tyrosine kinase created by the Philadelphia chromosome abnormality in chronic myeloid leukemia (CML) [16].It has also been found to be effective in the treatment of gastrointestinal stromal tumors (GISTs) [17].is selective inhibition of Bcr-Abl kinase by imatinib has been a successful therapeutic strategy for CML because of the high efficacy and mild side effects of this compound [18,19].Chloranilic acid (CA) and picric acid (PA) form salts with many organic compounds particularly with aromatic and aliphatic amines.

Experimental
All solvents and reagents were purchased from Sigma-Aldrich, India.Melting points were determined by Veego Melting Point VMP-III apparatus.Elemental analysis was carried out on Perkin Elmer 2400 elemental analyser.e UV-visible spectra were recorded on Analytikjena Specord 50 UV-vis spectrophotometer with quartz cell of 1.0 cm path length in DMSO.e infrared spectra on KBr pellets in the range of 4000-400 cm −1 were recorded on Jasco FT-IR 4100 series.FT-IR spectrophotometer provided with KBr optics.e NMR spectra were recorded using Bruker DRX 400 spectrometer at 400 MHz for 1 H NMR with tetramethylsilane as the internal standard.Compounds 1a-b and 2a-b were synthesized by the method summarized in Scheme 1.
2.1.General Procedure for the Synthesis of 1a and 2a.e reaction between imatinib intermediates (1.0 eq) with chloranilic acid (1.0 eq) in ethanol (10 mL).e reaction mixture was stirred at room temperature for 2 h, where the solid precipitated aer the reduction of the volume of the solvent.e separated precipitate was �ltered off, washed several times with diethyl ether (2 × 0.5 mL), and dried in vacuum over CaCl 2 .

General
Procedure for the Synthesis of 1b and 2b.e reaction between imatinib and its intermediates (1.0 eq) with picric acid (1.0 eq) in ethanol (10 mL).e reaction mixture was stirred at room temperature for 1 h, where the solid precipitated aer the reduction of the volume of the solvent.e separated precipitate was �ltered off, washed several times with diethyl ether (2 × 0.5 mL), and dried in vacuum over CaCl 2 .e crude product was puri�ed by crystallization from methanol solvent.

Antibacterial Activity.
Antibacterial activity of the synthesized compounds was determined against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli and Xanthomonas malvacearum ) in DMF by disc diffusion method on nutrient agar medium [20].e sterile medium (nutrient agar medium, 15 mL) in each Petri plates was uniformly smeared with cultures of Gram-positive and Gram-negative bacteria.Sterile discs of 10 mm diameter (Hi-Media) were made in each of the Petri plates, to which 50 L (1 mg/mL, that is, 50 g/disc) of the different synthesized compounds were added.e treatments also included 50 L of DMF as negative, streptomycin (1 mg/mL; 10 g/disc) as positive control for comparison.For each treatment, three replicates were maintained.e plates were incubated at 37 ± 2 ∘ C for 24 h, and the size of the resulting zone of inhibition, if any, was determined.
2.8.Antifungal Activity.e synthesized compounds were screened for their antifungal activity against Fusarium oxysporum in DMF by poisoned food technique [21].Potato dextrose agar (PDA) media were prepared, and about 15 mL of PDA was poured into each Petri plate and allowed to solidify.5 mm disc of seven-day-old culture of the test fungi was placed at the center of the Petri plates and incubated at 26 ∘ C for 7 days.Aer incubation, the percentage inhibition was measured and three replicates were maintained for each treatment.Nystatin was used as standard.All the synthesized compounds, and nystatin were tested (at the dosage of 500 L of the compounds/Petri plate, where concentration was 0.1 mg/mL) by poisoned food technique.

Results and Discussion
e elemental analyses data showed good agreement between the experimentally determined values and the theoretically calculated values within the limits of permissible error.New bands were detected in the UV-visible spectra of the salts.ese bands are not exhibited by either donor or acceptors alone.e appearance of longer wavelength absorption band in the visible region in UV-visible spectrum owing to the charge transfer transition con�rms the formation of products.Yield, melting point, and UV-visible spectral data of the synthesized salts are listed in

Conclusion
In conclusion, salts of pyrimidines with chloranilic and picric acids were synthesized in good yield, characterized by different spectral studies, and their antimicrobial activity has been evaluated.Compound 2a demonstrated good inhibition against all the strains tested.It should be noted that compound 2a demonstrated better inhibition compared to other compounds against bacterial and fungal strains tested.

Con�ict of �nterests
e authors report no con�ict of interests.e authors alone are responsible for the content and writing of the paper.

S 1 :
e illustration of the synthesis of 1a-b and 2a-b.

Table 1 .
e infrared spectra of the molecular salts of CA and PA with donors indicate that (C-Cl) of CA and (NO 2 ) of PA are shied to lower wavenumber values.estretchingT1: Physical characterization of the synthesized compounds.In vitro antibacterial and antifungal activities of synthesized compounds.Bacillus subtilis, Staphylococcus aureus, and Escherichia coli.Compound 2a exhibited good activity with the zone of inhibition in the range of 16 mm against pathogenic bacterial strain.3.2.Antifungal Activity.e antifungal activity of synthesized salts were evaluated and compared with standard drug nystatin.All the synthesized salts showed moderate inhibitory activity compared with standard drug.Compound 2a showed good antifungal activity with the 56.4% inhibition against F. oxysporum, compared with 2b, 1a, and 1b.Among the synthesized salts, inhibitory activity is in the order of 2a > 2b > 1a > 1b > against tested fungi.e compound 2a exhibited good activity against fungal strain.e salts of imatinib and its intermediates with chloranilic acid are more antimicrobial activity compared with salts of picric acid.Antimicrobial screening results of the tested salts are shown in