Antimicrobial Activity of Mixed Schiff Base Ligand Complexes of Ni(II), Cu(Ii) and Zn(II)

Coordination chemistry has benefited greatly from the discoveries of Schiff bases & their metal complexes. Hugo Schiff published the first account of Schiff base in 1864. By condensing amines and carbonyl compounds under various circumstances and in various solvents while removing water molecules, schiff bases may be made. Schiff bases are more often formed when a dehydrating agent is present. The Schiff bases serve as a foundation for the synthesis of several heterocyclic compounds even though they are stable solids. Due to their significance in the fields of medicine, agriculture, analysis, biology, and industry, the Schiff bases & their metal complexes have been the focus of considerable study. These compounds contain unusual structural features, intriguing spectroscopic, and magnetic characteristics.[1] Nickel (Ni):- Nickel serves crucial functions in the biology of bacteria and plants, despite not being identified until the 1970s. The active areas of urease include nickel complexes, which are widely exploited in the development of novel magnetic materials. Numerous facets of chemistry rely heavily on the research of nickel compounds. [2] Copper (Cu):- When assessing copper's biological availability in the environment and in food, its chemical makeup is crucial. The capacity of copper to regulate organism development is one of its many applications. This happens when copper is present physiologically and at harmful doses. Copper is thus used in a variety of cidal agents. For instance, copper has shown to be an efficient antibacterial and antiplaque ingredient in toothpaste and mouthwash.[3] Zinc (Zn):- With the help of ligands comprising N, S, O, halides, and CN, zinc may form stable complexes. Zn II) ion-containing compounds are often diamagnetic and colorless. No crystal lattice stabilization is possible with the d10 Configuration. The size & polarizing ability of the zinc (II) cation, as well as the steric needs of the ligands, determine the stereochemistry of a certain molecule. Thus, four coordinated tetrahedral compounds are preferred by Zn (II). [4] Increasing drug resistance has made Staphylococcus aureus a dangerous and more important pathogen . Despite sharing comparable phylogenetic origins with the CoNS, it is both different from and more virulent than the CoNS . Colonies of the aureus species (often) exhibit a golden color when grown on solid medium, whereas those of the CoNS variety are very light in color and transparent white .[5] The term "microorganism" is used to refer to a broad category that includes many different kinds of creatures. Bacteria are prokaryotic bacteria that do not possess chlorophyll as they divide by cytokinesis. Staining, oxygen consumption, carbon source, and shape are used to categorize them further. Pharmaceuticals known as antibacterials are used to combat bacterial growth. Penicillin G, Cephalothin, ampicillin, Amoxicillin, Clavamox, Streptomycin etc are few antibacterial drugs. Modes of action include blocking protein synthesis, beta- illnesses are: athlete‘s foot, ring worm, candidiasis , dangerous systemic infections like cryptococcal meningitis. Antifungal medicines typically utilized include Amphotericin B, Clotrimazole, miconazole, flucanazole and flucytosine. They are used to suppress systemic and severe fungal infections. They have numerous ways of activities such as changing porosity of cell membrane, blocking sterol production or competing with uracil.[6] Medications with antimicrobial properties are used to eliminate or slow the spread of microorganisms including bacteria, fungus, viruses, spirochaetes, protozoa, and so on. Almost every infectious illness in India can be traced back to bacteria, fungus, and viruses, from malaria to AIDS. With Fleming's 1929 discovery of the potent bactericidal substance pencillin and Domagk's 1935 discovery of synthetic compounds, sulfonamides with wide antimicrobial action, the current age of antimicrobial chemotherapy born. The development of novel antibiotics is now the primary method for combating bacterial resistance.[7]

E. coli, or Escherichia coli, is a bacterium that is often found inside the lower intestine of mammals and other warm-blooded creatures. It is Gram-negative, facultatively anaerobic, and rod-shaped (endotherms). While the vast majority of E. coli strains pose no threat to human health, some serotypes may cause severe food poisoning and are sometimes to blame for product recalls as a result of contamination. [8]

Pseudomonas aeruginosa is a member of the Pseudomonadaceae family and is a Gram-negative, aerobic rod bacterium. There are 12 other members of the P. aeruginosa family. P. aeruginosa, like other species in the genus, is widespread in both the environment and the human body. Researchers think that Pseudomonas bacteria are one of the few genuine plant pathogens. P. aeruginosa has emerged as an important opportunistic pathogen in medical settings. Nosocomial pathogen status has been confirmed by recent epidemiological research, especially for antibiotic-resistant strains of this microorganism. [9]

Increasing drug resistance has made Staphylococcus aureus a dangerous and more important pathogen . Despite sharing comparable phylogenetic origins with the CoNS, it is both different from and more virulent than the CoNS . Colonies of the aureus species (often) exhibit a golden color when grown on solid medium, whereas those of the CoNS variety are very light in is 2.8Mb . S. aureus has a thick protective layer called a cell wall that is 20-40 nm thick and has a rather amorphous appearance.[10-11]

Bioassays are useful for determining microbial activity and are essential in the development of new methods for measuring substances bioactivity. In this study, the antibacterial efficacy of all derivatives was examined, including their effectiveness against various strains of bacteria.[12] Rotate the soaked swab firmly against the top inner wall of the tube to express excess fluid, then dip it into the standard inoculums , being careful not to contaminate the inoculums. Spread the agar out evenly on the plate at a 60°C angle. Keep the cover on for 5-15 minutes to let the inoculums dry up.[13-14] Use an aseptic method for applying the discs. Place the discs such that the farthest points from each other are at least 24 millimeters. Discs containing sensitive organisms, as well as those containing penicillin and cephalosporins, are best implanted with their centers 30 mm apart.[15] Start incubating at 35 +_°C straight away and check results after 16-18 hours. It is important to incubate delicate organisms at the correct temperature and for the appropriate amount of time. Put the plates in an incubator at 35 °C right away, and check them after 20 to 24 hours to see how the fungi are doing. If the plate was streaked properly, the ensuing zones of inhibition will be perfectly round, and the resulting lawn will be roughly continuous. When no development has been seen after 24 hours of incubation, read the results after 48 hours.[16]

The disc diffusion technique was used to test the antibacterial efficacy of synthesized Schiff bases & their associated mixed ligand metal complexes against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Disk-centered inhibition zones were evaluated to determine optimal disc size for inhibition. Different microbial growth inhibition zones are mentioned. The metal complexes are shown to have more antibacterial action than that of the free ligand. hence, complexation enhances antibacterial action. Chelation theory also provides an explanation for why metal complexes have enhanced activity.[17-19]

3. Staphylococcus B) Photos of Zone of Inhibition 1. Escherichia coli 2) Pseudomonas aeruginosa 3) Staphylococcus

Cu, Ni and Zn metal complex 2{(E)-4(methylphenyl)iminomethyl}phenol) ligand

Schiff base metal complexes with antimicrobial action

A) Utilized Microorganisms 1. Escherichiacoli. 2. Pseudomonas aeruginosa 3. Staphylococcus B) Photos of Zone of Inhibition 1. Escherichia coli 2. Pseudomonas aeruginosa 3. Staphylococcus Cu,Ni& Zn metal complex 2{(E)-2(methylphenyl)iminomethyl}phenol)

Schiff base metal complexes with antimicrobial action

No Zone No Zone No Zone 1.SL2-Cu No Zone No Zone 16 mm 2. SL2-Ni No Zone No Zone No Zone 3. SL2-Zn No Zone No Zone No Zone From above observation table Cu, Ni and Zn complexes of ligand only Cu shows antimicrobial activity against Staphylococcus. [21]

The rational methods for the synthesis of metal - organic polymeric networks has been an intensively researched issue due to the huge potential for generating innovative materials with fascinating useful functions. Cooperation between the metal's first-coordination sphere and also the second-sphere non-covalent active sites is essential for the logical development of metal-organic biomolecules frame works. Recently, enantioselective synthesis and the study of chiral ligands have become significant areas of study. This is because chiral coordination polymers have several potential uses, including enantioselective production, asymmetric catalysis, the building of chiral supermolecular structure, and state-of-the-art material production. For many years, Schiff bases have been one of the most important chelating systems in coordination compounds, and the use of these molecules in the expanding area of material science is a prime example of this trend. Schiff bases and the transition metal complexes they form are essential to several biological processes, and this is well established. There has been a lot of study into how Schiff base ligands behave as donors when bound to metal ions. In light of recent research, it has antibacterial and antifungal treatments. The current study thus aims to synthesize and evaluate the physiochemical and antibacterial characteristics of certain potential organometallic complexes. In this research, we focus on Schiff base ligands bound to transition metals.

1. Ahmed, Nayaz, Mohd Riaz, Altaf Ahmed, and Madhulika Bhagat. (2015).Synthesis, characterisation, and biological evaluation of zn (II) complex with tridentate (NNO Donor) Schiff base ligand. International Journal of Inorganic Chemistry. Vol. 2015. Article ID. 607178. 5 pages. 2. Albert A, Selective Toxicity: The Physicochemical Basis of Therapy, 6th Ed., Chapaman and Hall, Londan, 1979. 3. Anacona, J. R., Natiana Noriega, and Juan Camus. (2015). Synthesis, characterization and antibacterial activity of a tridentate Schiff base derived from cephalothin and sulfadiazine, and its transition metal complexes. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. Vol. 137. 16-22. 4. Asadi, Mozaffar, Hajar Sepehrpour, and Khosro Mohammadi. (2011). Tetradentate Schiff base ligands of 3, 4-diaminobenzophenone: Synthesis, characterization and thermodynamics of complex formation with Ni (II), Cu (II) and Zn (II) metal ions. Journal of the Serbian Chemical Society, Vol. 76. No. 1. 63-74. 5. Chohan, Z. H., Perrvez, H. &Kausar, S. Synthesis and characterization of antibacterial Co(II), Cu(II), Ni(II), and Zn(II) complexes of acylhydrazine derived pyrrolyl compounds. Synth. React. Inorg. Met. -Org. Chem. 32, 529–543 (2002). 6. Dash D C, Meher F M, Monhanty P C and Nanda J, Indian J Chem., 1987, 26(A), 698-701. 7. Dutta R L, Syamal A, Elements of Magnatochemistry, 2 nd Ed., East west press, New Delhi, 1996. 8. Guan, Meng, Ngaini Zainab, Maya Asyikin, MohdArif, and Enggie Emelia. (2013). Complexation of bis-2-(benzylideneamino) phenol to cobalt (II) and zinc (II), and their spectroscopic studies. Borneo Journal of Resource Science and Technology. Vol. 3. No. 1. 26-34. 9. Jayabalakrishnan, C. & Natarajan, K. Ruthenium (II) carbonyl complexes with tridentate Schiff bases and their antibacterial activity. Trans. Met. Chem. 27, 75–79 (2002). 10. Joseyphus, R. Selwin, and M.Sivasankaran Nair. (2008). Antibacterial and antifungal Hamurcu, F. &Erk, B. Cr(III), Fe(III) and Co(III) complexes of tetradentate (ONNO) Schiff base ligands: Synthesis, characterization, properties and biological activity. Spectro. Chim. Acta A 70, 634–640 (2008). 12. Liver A B P, Inorganic electronic spectroscopy. Elsevier, New York, 1984. 13. Mahapatra B B and Patel B K, Indian J Chem., 1987, 26(A), 623-624. 14. Poonia, Kavita, Sahabjada Siddiqui, Md Arshad, and Dinesh Kumar. (2016). In vitro anticancer activities of Schiff base and its lanthanum complex. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. Vol. 155. 146-154 15. Saini, R. P., V. Kumar, A. K. Gupta, and G. K. Gupta. (2014). Synthesis, characterization, and antibacterial activity of a novel heterocyclic Schiff‘s base and its metal complexes of first transition series. Medicinal Chemistry Research. Vol. 23. No. 2. 690-698. 16. Shamsipur, M., Ghiasvand, A. R., Sharghi, H. &Naeimi, H. Solid phase extraction of ultra trace copper (II) using octadecyl silica membrane disks modified by a naphthol-derivative Schiff's base. Anal. Chim. Acta 408, 271–277 (2000). 17. Sharghi, H. &Nasseri, M. A. Schiff-base metal (II) complexes as new catalysts in the efficient, mild and regioselective conversion of 1,2-epoxyethanes to 2-hydroxyethyl thiocyanates with ammonium thiocyanate.. Bull. Chem. Soc. Jpn. 76, 137–142 (2003). 18. Vigato, P. A. &Tamburini, S. The challenge of cyclic and acyclic Schiff bases and related derivatives. Coord. Chem. Rev. 248, 1717–2128 (2004). 19. Wu, J. Z. & Yuan, L. Synthesis and DNA interaction studies of a binuclear ruthenium(II) complex with 2,9-bis(2-imidazo[4,5-f][1,10]phenanthroline)-1,10-phenanthroline as bridging and intercalating ligand. J. Inorg. Biochem. 98, 41–45 (2004). 20. You, Z. L., Tang, L. L. & Zhu, H. L. A dinuclear oxygen-bridged Schiff base iron(III) complex derived from N,N'-bis-(2-hydroxybenzylidene)- 1,2-diaminopropane. Acta. Crystallogr. 61, 36–38 (2005). 21. Ziyad, A., Tahaa, A. M., Ajlounia, W. A. M. &Abeer, A. Al-Ghzawia, syntheses, characterization, biological activities and photophysical properties of lanthanides complexes with a tetradentate Schiff base ligand. Spectro. Chim. Acta 81, 570–577 (2011).

Savitribai Phule, Pune University, Pune