ABSTRACT
The basic aim of this study pertains to the synthesis of silver nitrate complexes and the study of their antimicrobial and anticancer bio-activity. A series of new silver(i) derivatives of N-substituted-imidazolidine-2-thiones (L-NR, R = Et, Pr n , Bu n , Ph), purine-6-thione (purSH2), 2-thiouracil (tucH2), pyrimidine-2-thione (pymSH) and pyridine-2-thione (pySH) of composition [Ag(S-L-NR)(PPh3)2(ONO2)] {R = Et (1), Pr n (2), Bu n (3), Ph (4)}, [Ag2(N,S-purSH2)2(µ-dppm)2](NO3)2·2H2O (5) (dppm = Ph2P-CH2-PPh2), [Ag(L)(PPh3)2](NO3) {L = N,S-purSH2 (6); S-tucH2 (7)}, [Ag(N,S-pymS)(PPh3)2](CH3OH) (8), and [Ag(N,S-pyS)(PPh3)2] (9) have been synthesized and structurally characterized. These new and some previously reported complexes {[Ag2(L-NH)4(PPh3)2](NO3)2 (10), [Ag(L-NMe)2(PPh3)](NO3) (11), and [Ag(S-bzimSH)2(PPh3)2](OAc) (12), L-NH = 1,3-imidazolidine-2-thione; L-NMe = 1-methyl-3-imidazolidine-2-thione and bzimSH2 = benzimidazoline-2-thione)} have shown moderate to high anti-microbial activity against Gram positive bacteria, namely methicillin resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus (MTCC 740), and Gram negative bacteria, namely Staphylococcus epidermidis (MTCC 435), Enterococcus faecalis (MTCC 439), Shigella flexneri (MTCC 1457) and a yeast Candida albicans (MTCC 22). These complexes have also been found to be bio-safe as studied using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. The anti-tumor study of silver complexes against human osteosarcoma cell line (MG63) has shown IC50 values in the range of 6-33 µM.
ABSTRACT
The basic objective of this investigation is to explore potential metallo-organic antimicrobial agents based on silver-heterocyclic-2-thiones. In this respect, a series of silver(I) halide complexes with imidazolidine-2-thiones (L-NR, R=H, Me, Et, Prn, Bun, Ph), namely, mononuclear [AgX(L-NR)(PPh3)2] (X, R: Cl, Bu, 1; Br, Ph, 7); [AgX(L-NR)3] (Br, Bu, 5; Br, Prn, 8) and halogen bridged dinuclear [Ag2(µ-X)2(L-NR)2(PPh3)2] (Cl, Bun, 2; Cl, Ph, 3; Cl, Prn, 4; Br, Ph, 6) have been synthesized and characterized using modern techniques. The thio-ligands are terminally S-bonded in all the complexes. The in vitro antimicrobial potential and biosafety evaluation of the above complexes as well as that of previously reported analogous silver complexes has been studied against Gram positive bacteria, namely, Staphylococcus aureus (MTCC 740) and Methicillin resistant Staphylococcus aureus (MRSA), Gram negative bacteria Klebsiella pneumoniae (MTCC 109), Salmonella typhimurium (MTCC 98) and a yeast Candida albicans (MTCC 227). Most of the complexes tested have shown significant antimicrobial activity with low values of minimum inhibitory concentration (MIC). Significantly, the activity against MRSA is an important outcome of this investigation. Among complexes tested for their cytotoxicity using MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] assay, some complexes showed low cellular toxicity with high percent cell viability. A dinuclear complex [Ag2(µ-Cl)2(L-NPh)2(PPh3)2] 3 with 93.3% cell viability emerges the most important candidate for further investigations.
Subject(s)
Imidazolidines/chemistry , Silver/chemistry , Spectrometry, Mass, Electrospray Ionization , Thiones/chemical synthesis , Thiones/pharmacology , Anti-Infective Agents/chemical synthesis , Anti-Infective Agents/chemistry , Anti-Infective Agents/pharmacology , Anti-Infective Agents/toxicity , Bacteria/drug effects , Candida/drug effects , Cell Line , Cell Survival/drug effects , Coordination Complexes/chemical synthesis , Coordination Complexes/chemistry , Coordination Complexes/pharmacology , Crystallography, X-Ray , Humans , Microbial Sensitivity Tests , Molecular Structure , Structure-Activity Relationship , Thiones/chemistry , Thiones/toxicityABSTRACT
Correction for 'Variable coordination and C-S bond cleavage activity of N-substituted imidazolidine-2-thiones towards copper: synthesis, spectroscopy, structures, ESI-mass and antimicrobial studies' by Jaspreet K. Aulakh, et al., Dalton Trans., 2017, 46, 1324-1339.
ABSTRACT
An equimolar reaction of copper(i) iodide with N-ethyl-imidazolidine-2-thione (l-Et) in acetonitrile formed black prismatic crystals over a period of three weeks. The X-ray structure determination of black crystals revealed that the thio-ligand l-Et has transformed into a new thio-ligand, 1-ethyl-3-(1-ethyl-4,5-dihydro-1H-imidazol-2-yl)imidazolidine-2-thione (l-NEt), through C-S rupture/C-N bond formation which was coordinated in the unusual 2D polymer, {(CuII(κ2-N,S-l-NEt)2)·(CuI4)·(CuI2)}n1. An ESR spectrum supported the presence of divalent CuII in the polymer. In contrast, reaction of copper(i) iodide with N-phenyl-imidazolidine-2-thione (l-Ph) in 1 : 1 molar ratio yielded a polymer, [-Cu(µ-I)2Cu(µ-S-l-Ph)2Cu-]n2, with alternate Cu2I2 and Cu2S2 cores. Further, a series of reactions of copper(i) halides with N-substituted imidazolidine-2-thiones, namely, l-R in 1 : 2 metal to ligand molar ratio (M : L) in acetonitrile have yielded different type of complexes: trigonal planar {CuX(κ1-S-l-R)2, R, X : Et, I, 4; Me, I, 5; Bun, I,6; Me, Br,7; Bun, Br, 8; Me, Cl, 9; Prn, Cl, 10; Ph, Cl, 11}, dinuclear [Cu2Br2(µ-S-l-Ph)2(κ1-S-l-Ph)2] 12, tetranuclear, [Cu4I2(µ-I)2(µ-S-l-Ph)4(κ1-S-l-Ph)2] 3 and hexanuclear [Cu6Cl6(µ-S-l-Bun)6] 13. All these complexes have been characterized using analytical data, IR and proton NMR spectroscopy, ESI-mass studies and single crystal X-ray crystallography. The antimicrobial activity of these complexes has been investigated against Gram positive bacteria, namely, Staphylococcus aureus (MTCC740), methicillin resistant Staphylococcus aureus (MRSA), Gram negative bacteria, Klebsiella pneumoniae (MTCC109), Salmonella typhimurium (MTCC741) and Candida albicans (MTCC227)- a yeast. It is significant to add that among various complexes tested for cytotoxicity toward living cells, 4, 5, 8, 9 and 10 complexes were toxic, while complex 12 was non-toxic.
