Next Article in Journal
“Flash” Solvent-free Synthesis of Triazoles Using a Supported Catalyst
Previous Article in Journal
Antimutagenic Activity and Radical Scavenging Activity of Water Infusions and Phenolics from Ligustrum Plants Leaves
 
 
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Antimicrobial Activity of Some Thiourea Derivatives and Their Nickel and Copper Complexes

1
Department of Natural Sciences, Fayetteville State University, Fayetteville, NC 28301, USA
2
Department of Chemistry, Faculty of Pharmacy, Mersin University, Mersin, TR 33169, Turkey
3
Department of Microbiology, Faculty of Medicine, Mustafa Kemal University, Hatay, TR 31040, Turkey
4
Health School, Mersin University, Mersin, TR 33169, Turkey
*
Author to whom correspondence should be addressed.
Molecules 2009, 14(1), 519-527; https://doi.org/10.3390/molecules14010519
Submission received: 2 December 2008 / Revised: 24 December 2008 / Accepted: 5 January 2009 / Published: 22 January 2009

Abstract

:
Five thiourea derivative ligands and their Ni2+ and Cu2+ complexes have been synthesized. The compounds were screened for their in vitro anti-bacterial activity using Gram-positive bacteria (two different standard strains of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pyogenes, Bacillus cereus) and Gram-negative bacteria (Esherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Proteus vulgaris, Enterobacter aerogenes) and in vitro anti-yeast activity (Candida albicans, Candida krusei, Candida glabrata, Candida tropicalis, Candida parapsilosis). The minimum inhibitory concentration was determined for all ligands and their complexes. In vitro anti-yeast activity of both ligands and their metal complexes is greater than their in vitro anti-bacterial activity. The effect of the structure of the investigated compounds on the antimicrobial activity is discussed.

Graphical Abstract

Introduction

Industrial production and the use of Fe, Co, Cu, Ni, Zn, Cd, and Pb elements can cause environmental pollution. On the other hand, some of these metals are present in trace amounts as essential elements for biological systems and these metal ions also play an important role in bioinorganic chemistry. In order to understand the role of these metal ions in biological systems, structural studies of the biological compounds and their metal complexes are extremely important.
Compounds containing carbonyl and thiocarbonyl groups occupy an important position among organic reagents as potential donor ligands for transition metal ions [1,2,3,4,5,6,7]. Among these thiourea derivatives are potentially very versatile ligands, able to coordinate to a range of metal centres as neutral ligands, monoanions or dianions [1,2,3,4,5,6,7,8,9,10,11,12]. The oxygen, nitrogen and sulfur donor atoms of thiourea derivatives provide a multitude of bonding possibilities. Both the ligands and their metal complexes display a wide range of biological activity including antibacterial, antifungal, antitubercular, antithroid, antihelmintic, rodenticidal, insecticidal, herbicidal, and plant-growth regulator properties [13,14,15,16,17].
In view of this, our team focused on the synthesis, characterization, crystal structure, thermal behavior and antimicrobial activity of new thiourea derivatives [1,2,3,4,5,6,7,18,19,20,21,22,23,24,25]. Following our examination of the antimicrobial activity of thiourea derivative ligands and their metal complexes, we now report on the anti-bacterial and anti-yeast activity of five thiourea derivative ligands: (N-(diethylcarbamothioyl)cyclohexanecarboxamide [L1], N-(di-n-propylcarbamothioyl)cyclohexane carboxamide [L2] di-n-butylcarbamothioyl)cyclohexanecarboxamide [L3], N-(diphenylcarbamothioyl) cyclohexanecarboxamide [L4], N-(morpholine-4-carbonothioyl)cyclohexanecarboxamide [L5]) and their Ni2+ and Cu2+ metal complexes against standard bacterial (two different standard strains of Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Streptococcus pyogenes, Bacillus cereus, Esherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Proteus vulgaris, Enterobacter aerogenes) and yeast strains (Candida albicans, Candida krusei, Candida glabrata, Candida tropicalis, Candida parapsilosis).

Results and Discussion

The syntheses (Scheme 1) involve the reaction of a cyclohexanecarbonyl chloride with potassium thiocyanate in acetone, followed by condensation of the resulting cyclohexanecarbonyl isothiocyanate with an appropriate secondary amine (diethylamine, di-n-propylamine, di-n-butylamine, diphenylamine ormorpholine). The ligands were purified by re-crystallization from an ethanol-dichloromethane mixture (1:2). The reaction of the ligands with metallic salts at room temperature with ethanol as solvent yielded the related metal complexes.
In the light of interesting antimicrobial activities of the coordination complexes, the thiourea derivative ligands and their Ni2+ and Cu2+ metal complexes were screened for antibacterial and antifungal activity against S. aureus, S. epidermidis, E. faecalis, S. pyogenes, B. cereus, B. cereus, E. coli, P. aeruginosa, E. cloacae, P. vulgaris, E. aerogenes, C. albicans, C. krusei, C. glabrata, C. tropicalis, C. parapsilosis by the broth microdilution procedure. The Gram positive anti-bacterial agent, amikacin, the Gram negative anti-bacterial agent, gentamycin, and the anti-fungal agent, nystatin, were used as controls. The in vitro antimicrobial properties against a number of Gram positive and Gram negative bacteria, and yeasts of both ligands and their metal complexes are presented in Table 1, Table 2 and Table 3, respectively.
Scheme 1. Synthesis of the compounds.
Scheme 1. Synthesis of the compounds.
Molecules 14 00519 g001
Table 1. MIC values (μg/cm3) of the compounds against the tested Gram positive bacteria.
Table 1. MIC values (μg/cm3) of the compounds against the tested Gram positive bacteria.
CompoundS. aureus
(ATCC 25923)
S. aureus
(ATCC 29213)
S. epidermidis
(ATCC 12228)
E. faecalis
(ATCC 29212)
S. pyogenes
(Clinical isolate)
B. cereus
(Clinical isolate)
L1200200100400200200
L2400200200200200100
L3200400200200400200
L4100100100100200100
L5400200100100200200
NiL12200200200200200200
NiL22200200200200100200
NiL32200400100200100200
NiL42400400100200100100
NiL52200200200400200100
CuL12100200100200400100
CuL22100200200200400100
CuL32200400200200400200
CuL42200200200400400200
CuL5250100100200200100
Amikacin220.5412
Table 2. MIC values (μg/cm3) of the compounds against the tested Gram negative bacteria.
Table 2. MIC values (μg/cm3) of the compounds against the tested Gram negative bacteria.
CompoundE. coli
(ATCC 25922)
P. aeruginosa
(ATCC 27853)
E. cloacae
(ATCC 13047)
P. vulgaris
(ATCC 13315)
E. aerogenes
(Clinical isolate)
L1400400400200200
L2200400200200400
L3200400200200200
L4200400200200400
L5200400400200400
NiL12200400200200400
NiL22200400200200200
NiL32400400400200400
NiL42400400400400200
NiL52200400400400400
CuL12200400400400200
CuL22400400200200200
CuL32400400200100400
CuL42400400400200400
CuL52200400400400200
Gentamycin0.51220.5
Table 3. MIC values (μg/cm3) of the compounds against the tested fungi.
Table 3. MIC values (μg/cm3) of the compounds against the tested fungi.
CompoundC. albicans
(ATCC 90028)
C. krusei
(ATCC 6258)
C. glabrata
(ATCC 32554)
C. tropicalis
(ATCC 20336)
C. parapsilosis
(Clinical isolate)
L15050505050
L250502525100
L3100100252550
L42550505050
L55050505050
NiL1225505010025
NiL222550255050
NiL321001005010050
NiL4250252550100
NiL525050505050
CuL122550255050
CuL222550252525
CuL322550505050
CuL425025252550
CuL522525252525
Nystatin10.5244
All compounds inhibited the growth of bacteria with MIC values ranging between 50 and 400 μg/cm3 and showed anti-yeast activity with MICs between 25 and 100 μg/cm3. According to the antimicrobial studies, all compounds showed such activity, albeit lower than their anti-yeast efficacy. This difference may be due to the differences between the cell structures of bacteria and yeast. While the cell walls of fungi contain chitin, the cell walls of bacteria contain murein [17]. In addition, fungi contain ergosterol in their cell membranes instead of the cholesterol found in the cell membranes of animals [4,26].
CuL52 show good activity against C. albicans, C. krusei, C. glabrata, and C. tropicalis. NiL32 showed low activity against C. albicans, C. krusei, and C. tropicalis. When all the anti-yeast MIC values are compared, twelve of fifteen compounds show good activity against C. glabrata and ten of fifteen compounds show low activity against C. parapsilosis. According to the anti-bacterial studies, the efficacy against Gram positive bacteria is higher than against Gram negative bacteria. Eleven of fifteen compounds show good activity against S. epidermidis and eight of fifteen compounds show low activity against S. pyogenes. In addition, L4 showed high activity against all Gram positive bacteria.
The investigated compound antimicrobial activity values in this research were lower than that reported for other thiourea derivatives [4,6,17,19]. The main difference in the thiourea derivatives reported in this paper is the presence of the cyclohexyl moiety. The other derivatives included substituted benzyl groups. Lipophilicity, which correlates well with the bioactivity of chemicals, is a very important molecular descriptor and different lipophilic behaviour of compounds plays an important role in their biological activity mechanisms. The n-octanol/water partition coefficient (log Pow) is widely used as a general measure of lipophilicity. Compounds with benzyl groups have relatively higher log Pow values and hence show more lipophilic character as compared to the compounds with cyclohexyl groups [27].
It is interesting to note that the investigated compounds with cyclohexane group show lower anti-microbial activity. This behavior can be attributed to the fact that due to their low lipophilicity, these compounds do not penetrate into the microorganisms as easily as the thiourea derivatives with benzyl group do. Similar behavior is observed in the anti-yeast activity MIC values for CuL52 and NiL52. The compound with a morpholine ring, which has the log Pow value of 2.55, show higher anti-microbial activity than the other investigated compounds due probability to their higher lipophilic character.
The results show that the copper complexes are more active against the tested yeast as compared to the nickel complexes. The increase in antifungal activity of the copper complexes can be ascribed to the effect of the copper metal ion on the normal cell process. The complexation reaction reduces the polarity of the metal ion by the partial sharing of metal ion’s positive charge with donor groups and electron delocalization over the chelate ring. Thus, the lipophilic character of the central metal atom is enhanced which results in a higher capability to penetrate the microorganisms through the lipid layer of the cell membrane. Although MIC values for some compounds are good, unfortunately, the anti-yeast and anti-bacterial activity values of all tested compounds are lower than the reference compounds, thus these compounds cannot be suggested for clinical use.

Experimental

Synthesis

The ligands were prepared by a procedure similar to that reported in the literature (Scheme 1) [3]. A solution of cyclohexanecarbonyl chloride (0.005 mole) in acetone (30 mL) was added dropwise to a suspension of potassium thiocyanate (0.005 mole) in acetone (30 mL). The reaction mixture was heated (50 °C) under reflux for 30 min, and then cooled to room temperature. A solution of secondary amine (0.005 mole) in acetone (30 mL) was added and the resulting mixture was stirred for 2 h. Hydrochloric acid (0.1 N, 100 mL) was added and the solution filtered. The solid product was washed with water and purified by recrystallization from an ethanol-dichloromethane mixture (1:2). Metallic complexes were prepared according to the method described in the literature [3]. A solution of the metallic acetate (0.01mole) in ethanol (30 mL) was added dropwise to a solution of the ligand in a 1:2 ratio for all metal with a small excess of ligand in ethanol (30 mL) at room temperature and the resulting mixture was stirred for 30 min. The solid complexes were filtered and re-crystallized from a 1:2 ethanol-dichloromethane mixture.

Antimicrobial activity

The compounds were screened for their in vitro anti-bacterial and anti-yeast activities. Antimicrobial activities of both ligands and complexes were determined by the broth microdilution procedures and principles of the Clinical and Laboratory Standards Institute (CLSI) [28,29]. Minimal inhibitory concentrations for each compound were investigated against standard bacterial strains; S. aureus (ATCC 25923), S. aureus (ATCC 29213), S. epidermidis (ATCC 12228), E. faecalis (ATCC 29212), S. pyogenes (clinical isolate), B. cereus (clinical isolate), E. coli (ATCC 25922), P. aeruginosa (ATCC 27853), E. cloacae (ATCC 13047), P. vulgaris (ATCC 13315), E. aerogenes (clinical isolate), and yeast-like fungi; C. albicans (ATCC 90028), C. krusei (ATCC 6258), C. glabrata (ATCC 32554), C. tropicalis (ATCC 20336), C. parapsilosis (clinical isolate) obtained from the Refik Saydam Hıfzıssıhha Institute, Ankara, Turkey, Microbiology Culture Collection of Inonu University, Malatya, Turkey, and Department of Microbiology, Faculty of Medicine, Ege University, İzmir, Turkey. Bacterial and fungal colonies of the test organisms were suspended directly into a small volume of 0.9% saline and further diluted until turbidity matched the Mc Farland standard no: 0.5 Petri dishes containing Mueller-Hinton agar for bacteria and Sabouraud Dextrose agar for fungi were impregnated with these microbial suspensions. The stock solutions were prepared in dimethyl sulfoxide (DMSO), which had no effect on the microorganisms in the concentrations studied. All of the dilutions were done with distillated water. The concentrations of tested compounds were 400, 200, 100, 50, 25, 12.5, 6.25, 3.125 μg/cm3. DMSO was used as negative control. Amikacin, gentamycin, and nystatin were used as reference drugs for Gram positive anti-bacterial activity, Gram negative anti-bacterial activity and antifungal activity, respectively. All the inoculated plates were incubated at 35 °C and results were evaluated after 16-20 h for bacteria and 48 h for fungi. The lowest concentration of the compounds that prevented visible growth was considered to be minimal inhibitor concentrations (MICs).

Acknowledgements

Support for this research was provided by grant P20 MD001089 and S06 GM078246-01 from the USA National Institution of Health, NCMHD, and Department of Health and Human Services.

References

  1. Arslan, H.; Kulcu, N.; Florke, U. Synthesis and characterization of copper(II), nickel(II) and cobalt(II) complexes with novel thiourea derivatives. Transit. Metal Chem. 2003, 28, 816–819. [Google Scholar] [CrossRef]
  2. Mansuroglu, D.S.; Arslan, H.; Florke, U.; Kulcu, N. Synthesis and characterization of nickel and copper complexes with 2,2-diphenyl-N-(alkyl(aryl)carbamothioyl)acetamide: The crystal structures of HL1 and cis-[Ni(L-1)(2)]. J. Coord. Chem. 2008, 61, 3134–3146. [Google Scholar] [CrossRef]
  3. Ozer, C.K.; Arslan, H.; VanDerveer, D.; Binzet, G. Synthesis and characterization of N-(alky(aryl)carbamothioyl)cyclohexanecarboxamide derivatives and their Ni(II) and Cu(II) complexes. J. Coord. Chem. 2009, 62, 266–276. [Google Scholar] [CrossRef]
  4. Binzet, G.; Arslan, H.; Florke, U.; Kulcu, N.; Duran, N. Synthesis, characterization and antimicrobial activities of transition metal complexes of N,N-dialkyl-N'-(2-chloro-benzoyl)thiourea derivatives. J. Coord. Chem. 2006, 59, 1395–1406. [Google Scholar] [CrossRef]
  5. Ugur, D.; Arslan, H.; Kulcu, N. Synthesis, characterization and thermal behavior of 1,1-dialkyl-3-(4-(3,3-dialkylthioureidocarbonyl)benzoyl)thiourea and its Cu(II), Ni(II), and Co(II) complexes. Russ. J. Coord. Chem. 2006, 32, 669–675. [Google Scholar] [CrossRef]
  6. Emen, M.F.; Arslan, H.; Kulcu, N.; Florke, U.; Duran, N. Synthesis, characterization and antimicrobial activities of some metal complexes with N '-(2-chloro-benzoyl)thiourea ligands: The crystal structure of fac-[CoL3] and cis-[PdL2]. Pol. J. Chem. 2005, 79, 1615–1626. [Google Scholar]
  7. Arslan, H.; Florke, U.; Kulcu, N.; Emen, M.F. Crystal structure and thermal behaviour of copper(II) and zinc(II) complexes with N-pyrrolidine-N'-(2-chloro-benzoyl)thiourea. J. Coord. Chem. 2006, 59, 223–228. [Google Scholar]
  8. Henderson, W.; Nicholson, B.K.; Dinger, M.B.; Bennett, R.L. Thiourea monoanion and dianion complexes of rhodium(III) and ruthenium(II). Inorg. Chim. Acta 2002, 338, 210–218. [Google Scholar] [CrossRef]
  9. Sacht, C.; Datt, M.S.; Otto, S.; Roodt, A. Synthesis, characterisation and coordination chemistry of novel chiral N,N-dialkyl-N-menthyloxycarbonylthioureas. Crystal and molecular structures of N,N-diethyl-N-(-)-(3R)-menthyloxycarbonylthiourea and cis-(S,S)-[Pt(L)Cl(DMSO)] [where HL = N-(+)-(3R)-menthyloxycarbonyl-N'-morpholinothiourea or N-benzoyl-N',N'-diethylthiourea]. J. Chem. Soc., Dalton Trans. 2000, 24, 4579–4586. [Google Scholar] [CrossRef]
  10. Lipowska, M.; Hayes, B.L.; Hansen, L.; Taylor, A.; Marzilli, L.G. Rhenium(V) oxo complexes of novel N2S2 dithiourea (DTU) chelate ligands: Synthesis and structural characterization. Inorg. Chem. 1996, 35, 4227–4231. [Google Scholar] [CrossRef]
  11. Zuckerman, R.L.; Bergman, R.G. Structural factors that influence the course of overall [2+2] cycloaddition reactions between imidozirconocene complexes and heterocumulenes. Organometallics 2000, 19, 4795–4809. [Google Scholar] [CrossRef]
  12. Henderson, W.; Kemmitt, R.D.W.; Mason, S.; Moore, M.R.; Fawcett, J.; Russell, D.R. Thia-diazatrimethylenemethane and N,N',P-Triphenylphosphonothioic Diamide Complexes of Platinum(Ii). J. Chem. Soc., Dalton Trans. 1992, 1, 59–66. [Google Scholar]
  13. Yuan, Y.F.; Wang, J.T.; Gimeno, M.C.; Laguna, A.; Jones, P.G. Synthesis and characterisation of copper complexes with N-ferrocenoyl-N '(alkyl)thioureas. Inorg. Chim. Acta 2001, 324, 309–317. [Google Scholar] [CrossRef]
  14. Zhang, Y.M.; Wei, T.B.; Xian, L.; Gao, L. M. An efficient synthesis of polymethylene-bis-aroyl thiourea derivatives under the condition of phase-transfer catalysis. Phosphorus Sulfur Silicon Relat. Elem. 2004, 179, 2007–2013. [Google Scholar] [CrossRef]
  15. Zhang, Y.M.; Wei, T.B.; Wang, X.C.; Yang, S.Y. Synthesis and biological activity of N-aroyl-N '-carboxyalkyl thiourea derivatives. Indian J. Chem. Sect B 1998, 37, 604–606. [Google Scholar]
  16. Zhou, W. Q.; Li, B. L.; Zhu, L. M.; Ding, J. G.; Yong, Z.; Lu, L.; Yang, X. J. Structural and spectral studies on N-(4-chloro)benzoyl-N'-(4-tolyl)thiourea. J. Mol. Struct. 2004, 690, 145–150. [Google Scholar] [CrossRef]
  17. Eweis, M.; Elkholy, S.S.; Elsabee, M.Z. Antifungal efficacy of chitosan and its thiourea derivatives upon the growth of some sugar-beet pathogens. Int. J. Biol. Macromol. 2006, 38, 1–8. [Google Scholar] [CrossRef]
  18. Arslan, H.; Florke, U.; Kulcu, N. N'-(4-Chlorobenzoyl)-N,N-diphenylthiourea. Acta Cryst. E 2003, 59, O641–O642. [Google Scholar] [CrossRef]
  19. Arslan, H.; Florke, U.; Kulcu, N. Synthesis, characterization, and crystal structure of 1-(4-chloro-benzoyl)-3-naphthalen-1-yl-thiourea. J. Chem. Crystallogr. 2003, 33, 919–924. [Google Scholar] [CrossRef]
  20. Arslan, H.; Florke, U.; Kulcu, N. The crystal and molecular structure of 1-(biphenyl-4-carbonyl)-3-p-tolyl-thiourea. Acta Chim. Slov. 2004, 51, 787–792. [Google Scholar]
  21. Arslan, H.; Kulcu, N.; Florke, U. Normal coordinate analysis and crystal structure of N,N-dimethyl-N'-(2-chloro-benzoyl)thiourea. Spectrochim. Acta, Part A 2006, 64, 1065–1071. [Google Scholar] [CrossRef]
  22. Arslan, H.; Florke, U.; Kulcu, N. Theoretical studies of molecular structure and vibrational spectra of O-ethyl benzoylthiocarbamate. Spectrochim. Acta, Part A 2007, 67, 936–943. [Google Scholar] [CrossRef]
  23. Arslan, H.; Ozpozan, N.; Ozpozan, T. Thermal studies of p-toluidino-p-chlorophenylglyoxime and of some corresponding Ni(II), Cu(II) and Co(II) complexes. Thermochim. Acta 1999, 329, 57–65. [Google Scholar] [CrossRef]
  24. Avsar, G.; Kulcu, N.; Arslan, H. Thermal behaviour of copper(II), nickel(II), cobalt(II) and palladium(II) complexes of N,N-dimethyl-N '-benzoylthiourea. Turk. J. Chem. 2002, 26, 607–615. [Google Scholar]
  25. Ugur, D.; Florke, U.; Kulcu, N.; Arslan, H. 3-[4-(3,3-diethylthioureidocarbonoyl)-benzoyl]-1,1-diethylthiourea. Acta Cryst. E 2003, 59, O1345–O1346. [Google Scholar] [CrossRef]
  26. Fleet, G.H. Composition and Structure of Yeast Cell Walls: Current Topics in Medical Mycology; Springer-Verlag: New York, USA, 1985; Vol. 1. [Google Scholar]
  27. Hoey, A.J.; Jackson, C.M.; Pegg, G.G.; Sillence, M.N. Characteristics of cyanopindolol analogues active at the beta(3)-adrenoceptor in rat ileum. Br. J. Pharmacol. 1996, 119, 564–568. [Google Scholar] [CrossRef]
  28. National Committee for Clinical Laboratory Standards. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically, Approved Standard M7-A4; NCCLS: Viallanova, PA, USA, 1997. [Google Scholar]
  29. National Committee for Clinical Laboratory Standards. Reference method for broth dilution antifungal susceptibility testing of yeasts, Approved Standard M27-A2; NCCLS: Wayne, PA, USA, 2002. [Google Scholar]
  • Sample Availability: Samples of the compounds are available from the authors.

Share and Cite

MDPI and ACS Style

Arslan, H.; Duran, N.; Borekci, G.; Koray Ozer, C.; Akbay, C. Antimicrobial Activity of Some Thiourea Derivatives and Their Nickel and Copper Complexes. Molecules 2009, 14, 519-527. https://doi.org/10.3390/molecules14010519

AMA Style

Arslan H, Duran N, Borekci G, Koray Ozer C, Akbay C. Antimicrobial Activity of Some Thiourea Derivatives and Their Nickel and Copper Complexes. Molecules. 2009; 14(1):519-527. https://doi.org/10.3390/molecules14010519

Chicago/Turabian Style

Arslan, Hakan, Nizami Duran, Gulay Borekci, Cemal Koray Ozer, and Cevdet Akbay. 2009. "Antimicrobial Activity of Some Thiourea Derivatives and Their Nickel and Copper Complexes" Molecules 14, no. 1: 519-527. https://doi.org/10.3390/molecules14010519

Article Metrics

Back to TopTop