Synthesis, characterization and antimicrobial activity of novel tetrazoles clubbed with pyrimidine

An attempt was made to synthesize pyrimidine tetrazole derivatives of pharmaceutical interest by oxidative cyclization of chalcones with adequate yield and purity, prompted by the diversity of their wider usage and the fact that they are an integral part of genetic content. The present work involves the reaction of 5-(2,6- dimethylphenyl)-1H-tetrazole with acetic anhydride to yield 1-[5-(2,6-dimethylphenyl)-1H-tetrazol-1-yl] ethanone (1) and which then treated with different aromatic aldehydes in presence of alkaline medium to chalcones (2a-f). Reaction of chalcones (2a-f) with urea and thiourea to produce 5-[5-(2,6-dimethylphenyl)-1H-tetrazol-1-yl]-4-(substituted aryl ) pyrimidin-2-ol (3a-f) and 5-[5-(2,6-dimethylphenyl)-1H-tetrazol-1- yl]-4-(substituted aryl) pyrimidin-2-thiol (4a-f) respectively. All compounds were characterized by infrared spectroscopy (IR), 1 H nuclear magnetic resonance (NMR), and mass spectrometry (MS) to prove the structure and assessed in vitro for their efﬁcacy as antibacterial and antifungal activity against four bacteria. The compounds 3c, 3d and 3f and compounds 4c, 4d and 4f possess very good activity against S . aureus and E. coli and the compounds 3e, 3c and 3a and compounds 4e,4b and 4c possess very good activity against fungi Candida albicans and Aspergillus niger . This is an Open Access (OA) journal, and articles are distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as appropriate credit is given and the new creations are licensed under the identical terms.


Introduction
Since they are a diverse group of natural and synthetic products, many of which have biological applications, nitrogen-containing heterocycles are extremely important. Pyrimidine, which is present in DNA and RNA, has a variety of pharmacological properties, including bactericide, fungicide, vermicide, insecticide, anticancer, and antiviral. 1 Some pyrimidine derivatives reported as Anti-HIV-1 agents, 2 antileishmanial, 3 Anti-inflammatory, 4 Anticancer, 5 antimicrobial Antimalarial. 6 To date, a wide range of pyrimidine and pyrimidine-fused heterocyclic compounds have been documented to have anticancer activity through a variety of mechanisms and targets. [7][8][9] Pyrimidine derivatives 10,11 have played a significant role in the evolution of heterocyclic chemistry and have been widely used as pharmacophores and synthons in organic chemistry. A considerable amount of research effort has been centered on these nuclei due to their flexible chemotherapeutic significance. There has been significant progress in this area since the discovery of many synthetic and semi-synthetic antibacterial sulfa products, nitrofuranes, penicillins, cephalosporins, tetracyclines, macrolides, oxazolidinones, and antifungal agents such as fluconazole, ketoconazole, and miconazole, as well as amphotericin B. Despite advancements in antibacterial and antifungal therapies, most antimicrobial drugs still have a long way to go. Antibiotic overuse has resulted in the emergence of multidrug-resistant microbial pathogens. 12 Pyrimidine based heterocycles are potential bioactive molecules and exhibit antimicrobial, 13,14 anti-inflammatory, 11 antioxidant, 15 anticancer, 16 antihypertensive 17 and anticonvulsant. 18 Tetrazole has a great importance as it is bioactive molecules and exhibit antimicrobial, 19 anti-bacterial 20 anti-inflammatory 21 , antioxidant, 22 anticancer 23 ant tubercular, 24 anti-fungal, 24 antihypertensive 25 , anticonvulsant 26 and also act as enzyme inhibitors. Inspired from these facts, in present work an attempt is being made to synthesize pyrimidine's containing tetrazole and evaluate for antimicrobial activity which has not been reported yet. Hence the present work deals with the reaction of 1-[5-(2,6-dimethylphenyl)-1H-tetrazol-1-yl] ethanone (1) with different aromatic aldehydes in presence of alkaline medium to form (2E)-1-[5-(2,6-dimethylphenyl)-1H-tetrazol-1-yl]-3-(substituted aryl)prop-2-en-1-one (2a-f). Reaction of (2a-f) with urea and thiourea to produce 5-[5-(2,6-dimethylphenyl)-1Htetrazol-1-yl]-4-(substituted aryl )pyrimidin-2-ol (3a-f) and 5-[5-(2,6-dimethylphenyl)-1H-tetrazol-1-yl]-4-(substituted aryl) pyrimidin-2-thiol (4a-f) respectively. The structure of all the various synthesized compounds were assigned on the basis of IR, 1 H NMR spectral data and elemental analysis. These compounds were screened for their antimicrobial activity.

Materials and Methods
Melting points were determined with open capillary. FT-IR spectra were recorded on a Jasco model 4010 spectrophotometer, 1 H NMR spectra were recorded in DMSO on a Varian mercury FT-NMR model YH-300 instrument using TMS as internal standard. Mass spectra were recorded on GC-MS auto tune EI instrument.

Synthesis of
in anhydrous ethanol (50 mL), thiourea (0.01 mole) and aqueous sodium hydroxide (0.01 mole). The reaction mixture was refluxed for 5 hrs and poured into ice cold water the product obtained was filtered, washed with water and crystallized from aqueous ethanol. The purity of the compound was established by TLC using a mixture of hexane and ethyl acetate (6:4) as a mobile phase.

Antibacterial and antifungal activity
All the newly synthesized compounds were screened for antimicrobial activity against both gram positive S. aureus and gram negative E.coli bacteria and antifungal activity against C. albicans and A. niger according to cup plate method 13 at a concentration 100ug/0.1ml respectively. Streptomycin and clotrimazole were used as standard for comparison of antibacterial and antifungal activity 14 Indian Pharmacopoeia 15 . Solvent dimethyl sulphoxide (DMSO) was used as control. The results of screening are given inTable 2.

Antibacterial and antifungal activity
The antibacterial activity was evaluated by zone of inhibition method at 100 µg/0.1ml concentration. The results of antibacterial were compared with standard drug ciprofloxacin. Most of the synthesized compounds showed antibacterial activity against the tested Bacteria. It is evident that most of the compounds are very weakly active and few are moderately active against S. aureus and E. coli but compounds 3c, 3d and 3f and compounds 4c, 4d and 4f possess very good activity against S. aureus and E. coli at concentration of 100ug/0.1ml.
Similarly, the results of preliminary antifungal bioassays were compared with standard drug clotrimazole. Most of the synthesized compounds showed antifungal activity against the tested fungi. It is evident that the compounds 3e, 3c and 3a and compounds 4e,4b and 4c possess very good activity against fungi Candida albicans and Aspergillus niger at concentration of 100ug/0.1mL.Compound 3d and 4f showed moderate activity all bacteria and fungi tested

Conclusion
Tetrazole and Pyrimidine an important group of heterocyclic compounds reported to have different biological activities and hence the present studies were undertaken in order to synthesize Tetrazole clubbed with pyrimidines in order to potentiate the combined therapeutic effect of both heterocyclic compounds. So all the synthesized compounds were investigated them for their antibacterial and antifungal activity. Compounds with thiopene, furan and pyrrole substituents on pyrimidine clubbed with Tetrazole exhibited significant antibacterial and antifungal activity when compared with control. The compounds with pyrimidines substituents groups showed significant activity when compared to standard drug ciprofloxacin and clotrimazole respectively.

Source of Funding
None.

Conflict of Interest
None.