Acta Scientific Pharmaceutical Sciences (ISSN: 2581-5423) Volume 4 Issue 5 May 2020 Research Article Transition Metal Complexes of Schiff Base Ligand Derived from Trimethoprim with Cyclohexanone: Synthesis, Characterization, Antimicrobial and Computational Studies Hussaini Garba 1 *, Jamila Bashir Yakasai 2 , Ibrahim Waziri 3 and Ibraheem O Bisiriyu 4 1 Department of Science Laboratory Technology, Ramat Polytechnic, Maiduguri, Borno State, Nigeria 2 National Water Resources Institute, Mando, Kaduna State, Nigeria 3 Department of Pure and Applied Chemistry, University of Maiduguri, Maiduguri, Nigeria 4 Department of Chemical Sciences, Faculty of Science, University of Johannesburg, South Africa *Corresponding Author: Hussaini Garba, Department of Science Laboratory Technology, Ramat Polytechnic, Maiduguri, Borno State, Nigeria. Citation: Hussaini Garba., et al. “Transition Metal Complexes of Schiff Base Ligand Derived from Trimethoprim with Cyclohexanone: Synthesis, Characterization, Antimicrobial and Computational Studies". Acta Scientific Pharmaceutical Sciences 4.5 (2020): 36-45. Received: March 31, 2020 Published: April 29, 2020 © All rights are reserved by Hussaini Garba., et al. Abstract Keywords: Bacterial Resistance; Bacteria; Trimethoprim; Schiff Base; Complexes In this study, Metal (II) Complexes of Mn (II), Fe (III), Co (II) and Ni (II) with Schiff base ligand derived from Trimethoprim and Cyclohexanone were synthesized and characterized using various physic-chemical techniques such as: solubility, conductivity, melt- ing point determination, UV/Vis and Fourier transform infrared, 1H-NMR and elemental analysis. On the basis of these character- izations, a six coordinated octahedral geometry has been proposed for all the complexes. The Schiff base ligand and its complexes were screened for their antimicrobial activity against some pathogenic microbial isolate and compared with the parent drug. The antimicrobial activity results showed the following trend: metal complexes > Schiff base ligands > Parent drugs. This suggests poten- tial antimicrobials agents with broad spectrum activity. Computational studies further revealed that M-Cl bond is responsible for the trend in antimicrobial properties among the complexes. Introduction Bacterial resistance to antibiotics is a global public health con- cern that required urgent attention [1]. Without urgent and con- certed action, we are moving toward an era in which common in- fections or minor diseases may become uncontrolled [2]. Centre for diseases control and prevention (CDC) has issued guideline for addressing the menace with emphasis on promoting and develop- ment of new antibiotics that can address the drug-resistance bac- teria [3]. Generally, resistance occurs in nature. However, due to the inappropriate use of antibiotics in the area of treatment of dis- eases and prophylaxis bacteria are exposed to antibiotics more fre- quent and resistant become common [4]. There are various ways for which bacteria becomes resistance to antibiotics to antibiotics. The most common is through the process of natural selection [4]. In this regards, resistance is said to occur when not all bacteria are harmed by the antibiotics used for the treatment of particular infection and the surviving ones produce new generation of bac- teria that will be resistance to that antibiotic [4]. Resistance also can emerge by mutations that alter the drug binding sites on mo- lecular targets and by increasing expression of endogenous efflux pump [5]. Due to the increased rate of bacterial resistance to an- tibiotics, in February 2017, world health organization (WHO) re- leased the list of bacteria that pose threat human health [6]. The list consist of Klebsiella, E. coli and Pseudomonas as multidrug re- sistant bacteria that pose a particular threat to public health and often cause severe and deadly infection [4]. Also, among the list in- cludes Staphylococcus, Streptococcus and Salmonella [4]. It is very important to find compounds that can inhibit the growth of these bacteria. These bacteria are opportunistic and nosocomial patho- gens and are multi-drug resistant. Pseudomonas aeruginosa has a highly impermeable outer membrane that prevents the uptake of most molecules including several antibiotics [7]. This result in dif- ficulty of getting new antimicrobial agent that can prevent infection due Pseudomonas aeruginosa [8]. Staphylococcus aureus, a member of Gram-positive bacterium and also very common among people causes a lot infections, Staphylococcus aureus resistant to various antibiotics has resulted to the evolution of different strains of bac- teria such as methicillin-resistance Staphylococcus aureus (MRSA) [9]. Although, Staphylococcus aureus drug-resistant has reduced significantly, but MRSA resistant strains is still a major threat to the public health [10]. Recently, have reported the synthesis of Mn (II) and Fe (III) with Schiff base derived from trimethoprim with salicylaldehyde and benzaldehyde as potential antimicrobial agent and were found to showed good activity on both Gram-positive and Gram-negative bacteria [11]. Trimethoprim, systematically named as 2,4-diamine pyrimidine -5-(3, 4,5-Trimethoxybenzyl) is on the World Health Organization’s list of essential medicines, the most important medications needed in a basic health system [12]. Trimethoprim was commonly used in a 1:5 combination with sulfamethoxazole, a sulfonamide antibiotic.