New antibacterial, non-genotoxic materials, derived from the functionalization of the anti-thyroid drug methimazole with silver ions

Tetracycline: structural characterization and antimicrobial properties of its water-soluble di-anionic bi-sodium salt

The new water-soluble di-anionic bi-sodium salt of tetracycline (TC), an antibiotic in clinical use, with the formula {[TC]2-[Na+(MeOH)(H2O)] [Na+]·(H2O)}n (TCNa) was synthesized. The compound was characterized by m.p., attenuated total reflectance-Fourier transform infra-red (ATR-FTIR) spectroscopy, and ultraviolet (UV) and proton nuclear magnetic resonance (1H NMR) spectroscopy in the solid state and in solution. The molecular weight (MW) was determined by cryoscopy. The crystal structure of TCNa was also determined by X-ray crystallography. The antibacterial activity of TCNa was evaluated against the bacterial species Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus) by means of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and inhibition zones (IZs). Moreover, the ability of the compound to eradicate biofilm formation was also evaluated. The results are compared with those obtained for the commercially available drug TCH2. The in vitro and in vivo toxicities of TCNa were tested against human corneal epithelial cells (HCECs) and Artemia salina.

Multifunctional O-phenanthroline silver(I) complexes for antitumor activity against colorectal adenocarcinoma cells and antimicrobial properties by multiple mechanisms

A series of O-phenanthroline silver(I) complexes were synthesized and characterized by infrared (IR) spectroscopy, mass spectrometry (MS), ¹H nuclear magnetic resonance (NMR) spectroscopy and single-crystal X-ray crystallography. The cytotoxicity of the silver(I) complex (P-131) was evaluated in the cancer cell lines HCT-116, HeLa, and MDA-MB-231 and the normal cell line LO2 via MTT assays. The 50% inhibition concentration (IC₅₀) of P-131 on HCT116 cell line is 0.86 ± 0.03 μM. It is far lower than the IC₅₀ value of cisplatin (9.08 ± 1.10 μM), the IC₅₀ value of normal cell LO2 (76.20 ± 0.48 μM) is much higher than that of cisplatin (3.99 ± 0.74 μM), indicating that its anticancer effect is stronger than that of cisplatin, and its biological safety is greater than that of cisplatin. Furthermore, anticancer mechanistic studies showed that P-131 inhibited cell proliferation by blocking DNA synthesis and acted temporally on the nucleus in dividing HCT-116 cells. Moreover, P-131 increased intracellular reactive oxygen species (ROS) levels in a dose-dependent manner. Notably, 10 mg/kg P-131 showed better antitumor effects than oxaliplatin in an HCT116 human colorectal xenograft mouse model without inducing toxicity. Moreover, the microdilution broth method was used to evaluate the antimicrobial properties of P-131 against Pseudomonas aeruginosa and Candida albicans. A biofilm eradication study was also performed using the crystal violet method and confocal laser scanning microscopy.

New Hg(II) coordination polymers based on a thioimidazole ligand with good performance to detoxify Hg(II) and reversibly capture iodine

In the current paper, we have successfully synthesized three new mercury coordination polymers with fascinating structures and properties via a flexible sulfur donor ligand, namely, {[Hg(μ₂-Cl)(μ₂-Ls)]}_n[BF₄]_n(1), {[Hg(μ₂-Cl)(μ₂-Ls)]}_n[ClO₄]_n(2), and [Hg(SCN)₂(μ₂-Ls)]_n(3) [Ls = 1,1-bis(3-methyl-4-imidazoline-2-thione)methane]. These complexes have been characterized by means of different techniques such as single crystal X-ray crystallography, FT-IR, elemental analysis (CHNS), UV-Vis, PXRD, BET, and TGA. Suitable single crystals of all complexes were obtained using the branch tube method with a very high yield and good stability due to the high affinity of mercury to bind to the thione groups. The cationic moieties of polymers 1 and 2 were isostructural, with a HgCl₂S₂ coordination core structure. The voids of the quasi-hexagonal packing of the columnar chains were occupied by unbonded tetrahedral BF₄^- ions in 1 and perchlorate anions in polymer 2. Polymer 3 has a less distorted tetrahedral geometry than 1 and 2, with a HgS₄ core structure. By considering the thiophilicity of mercury, a thioamide-based Ls ligand was used to detoxify Hg(II) into insoluble polymers 1-3. The results of an MTT assay for (HepG2) liver cells confirmed the excellent cytoprotective effect of this ligand against mercury. Based on IC₅₀ calculations, their toxicity was in order of polymer 1 > polymer 2 > polymer 3. These polymers were also considered as adsorbents for the reversible removal of iodine from solution and the kinetics of the process has been studied in detail. Interestingly, all of them showed an excellent stability and high capacity, in order of 763.53 mg g^-1, 877.10 mg g^-1, and 905.31 mg g^-1 for polymers 1-3, respectively.

Assessment of the biological effect of metal ions and their complexes using Allium cepa and Artemia salina assays: a possible environmental implementation of biological inorganic chemistry

The pollution of aquatic ecosystems due to the elevated concentration of a variety of contaminants, such as metal ions, poses a threat to humankind, as these ecosystems are in high relevance with human activities and survivability. The exposure in heavy metal ions is responsible for many severe chronic and pathogenic diseases and some types of cancer as well. Metal ions of the groups 11 (Cu, Ag, Au), 12 (Zn, Cd, Hg), 14 (Sn, Pb) and 15 (Sb, Bi) highly interfere with proteins leading to DNA damage and oxidative stress. While, the detection of these contaminants is mainly based on physicochemical analysis, the chemical determination, however, is deemed ineffective in some cases because of their complex nature. The development of biological models for the evaluation of the presence of metal ions is an attractive solution, which provides more insights regarding their effects. The present work critically reviews the reports published regarding the toxicity assessment of heavy metal ions through Allium cepa and Artemia salina assays. The in vivo toxicity of the agents is not only dose depended, but it is also strongly affected by their ligand type. However, there is no comprehensive study which compares the biological effect of chemical agents against Allium cepa and Artemia salina. Reports that include metal ions and complexes interaction with either Allium cepa or Artemia salina bio-indicators are included in the review.

Environmental Remediation through Catalytic Inhibition of Steel Corrosion by Schiff’s Bases: Electrochemical and Biological Aspects

The environmental impact of corrosion is very dangerous and consumes much of world’s efforts and funds. This work discusses the safeguarding of the environment, metals, and metal-infra structures by efficient Schiff’s base inhibitors. The corrosion inhibitors [(1E,3E)-N1,N3-dibutyl-1-(thiophen-2-yl)butane-1,3-diimine] (GSB-I) and [(1Z,3Z)-N1,N3-bis(4-methylhexan-2-yl)-1-(thiophen-2-yl)butane-1,3-diimine] (GSB-II) were successfully synthesized and evaluated for the protection of API 5L X65 steel (CS) in 1 M HCl media using electrochemical techniques, SEM/EDS, and quantum chemical calculations. GSB-I and GSB-inhibitory I’s efficiency is proportional to the concentration of the test. In the presence of 1 mM GSB-I and GSB-II, the maximum inhibitory efficiency was determined to be 90.6 and 93.8 percent, respectively. According to potentiodynamic polarization tests, the two compounds are effective inhibitors of mixed-type corrosion. The physisorption and chemisorption of both inhibitors followed the Langmuir adsorption isotherm on CS surfaces. The biological reactivity of both GSB has been examined, and encouraging results have been obtained as antifungal, antibacterial, and biocidal agents against sulfate-reducing bacteria (SRB). In addition, using DFT calculations and molecular dynamic (MD) simulation, the effect of GSB-I and GSB-II molecular configuration on corrosion inhibition behavior in acidic environments was investigated.

Hydrogels containing water soluble conjugates of silver(I) ions with amino acids, metabolites or natural products for non infectious contact lenses

The poor handling and hygiene practices of contact lenses are the key reasons for their frequent contamination, and are responsible for developing ocular complications, such as microbial keratitis (MK). Thus there is a strong demand for the development of biomaterials of which contact lenses are made, combined with antimicrobial agents. For this purpose, the known water soluble silver(I) covalent polymers of glycine (GlyH), urea (U) and the salicylic acid (SalH₂) of formulae [Ag₃(Gly)₂NO₃]_n (AGGLY), [Ag(U)NO₃]_n (AGU), and dimeric [Ag(salH)]₂ (AGSAL) were used. Water solutions of AGGLY, AGU and AGSAL were dispersed in polymeric hydrogels using hydroxyethyl-methacrylate (HEMA) to form the biomaterials pHEMA@AGGLY-2, pHEMA@AGU-2, and pHEMA@AGSAL-2. The biomaterials were characterized by X-ray fluorescence (XRF) spectroscopy, thermogravimetric differential thermal analysis (TG-DTA), differential scanning calorimetry (DTG/DSC), attenuated total reflection spectroscopy (FT-IR-ATR) and single crystal diffraction analysis. The antibacterial activity of AGGLY, AGU, AGSAL, pHEMA@AGGLY-2, pHEMA@AGU-2 and pHEMA@AGSAL-2 was evaluated against the Gram negative species Pseudomonas aeruginosa (P. aeruginosa) and Gram positive ones Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus), which mainly colonize in contact lenses. The in vitro toxicity of the biomaterials and their ingredients was evaluated against normal human corneal epithelial cells (HCECs) whereas the in vitro genotoxicity was evaluated by the micronucleus (MN) assay in HCECs. The Artemia salina and Allium cepa models were applied for the evaluation of in vivo toxicity and genotoxicity of the materials. Following our studies, the new biomaterials pHEMA@AGGLY-2, pHEMA@AGU-2, and pHEMA@AGSAL-2 are suggested as efficient candidates for the development of antimicrobial contact lenses.

Ciprofloxacin conjugated to diphenyltin(IV): a novel formulation with enhanced antimicrobial activity

The metalloantibiotic of formula Ph2Sn(CIP)2 (CIPTIN) (HCIP = ciprofloxacin) was synthesized by reacting ciprofloxacin hydrochloride (HCIP·HCl) (an antibiotic in clinical use) with diphenyltin dichloride (Ph2SnCl2DPTD). The complex was characterized in the solid state by melting point, FT-IR, X-ray Powder Diffraction (XRPD) analysis, 119Sn Mössbauer spectroscopy, X-ray Fluorescence (XRF) spectroscopy, and Thermogravimetry/Differential Thermal Analysis (TG-DTA) and in solution by UV-Vis, 1H NMR spectroscopic techniques and Electrospray Ionisation Mass Spectrometry (ESI-MS). The crystal structure of CIPTIN and its processor HCIP was also determined by X-ray crystallography. The antibacterial activity of CIPTIN, HCIP·HCl, HCIP and DPTD was evaluated against the bacterial species Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis), by the means of Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and Inhibition Zones (IZs). CIPTIN shows lower MIC values than those of HCIP·HCl (up to 4.2-fold), HCIP (up to 2.7-fold) or DPTD (>135-fold), towards the tested microbes. CIPTIN is classified into bactericidal agents according to MBC/MIC values. The developing IZs are 40.8 ± 1.5, 34.0 ± 0.8, 36.0 ± 1.1 and 42.7 ± 0.8 mm, respectively which classify the microbes P. aeruginosa, E. coli, S. aureus and S. epidermidis to susceptible ones to CIPTIN. These IZs are greater than the corresponding ones of HCIP·HCl by 1.1 to 1.5-fold against both the tested Gram negative and Gram positive bacteria. CIPTIN eradicates the biofilm of P. aeruginosa and S. aureus more efficiently than HCIP·HCl and HCIP. The in vitro toxicity and genotoxicity of CIPTIN were tested against human skin keratinocyte cells (HaCaT) (IC50 = 2.33 μM). CIPTIN exhibits 2 to 9-fold lower MIC values than its IC50 against HaCaT, while its genotoxic effect determined by micronucleus assay is equivalent to the corresponding ones of HCIP·HCl or HCIP.

Dinuclear silver(i) complexes with a pyridine-based macrocyclic type of ligand as antimicrobial agents against clinically relevant species: the influence of the counteranion on the structure diversification of the complexes

New dinuclear silver(i) complexes with N,N',N'',N'''-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc), [Ag2(NO3)(tpmc)]NO3·1.7H2O (1), [Ag2(CF3SO3)2(tpmc)] (2), and [Ag2(tpmc)](BF4)2 (3) were synthesized and characterized by NMR (1H and 13C), IR and UV-Vis spectroscopy, cyclic voltammetry and molar conductivity measurements. The molecular structures of the complexes were determined by single-crystal X-ray diffraction analysis. The spectroscopic and crystallographic data showed that the structure of the complexes strongly depends on the nature of the counteranion of silver(i) salt used for their synthesis. The antimicrobial activity of complexes 1-3 was examined against Gram-positive and Gram-negative bacteria and different species of unicellular fungus Candida spp. The ability of these complexes to inhibit the formation of Candida biofilms and to eradicate the already formed biofilms was tested in the standard microtiter plate-based assay. In addition, a bioelectrochemical testing of the antimicrobial activity of complex 1 against early biofilm was also performed. The obtained results indicated that complexes 1-3 showed increased activity toward Gram-negative bacteria and Candida spp. and could inhibit the formation of biofilms. In most cases, these complexes had positive selectivity indices and showed similar or even better activity with respect to the clinically used silver(i) sulfadiazine (AgSD). The values of the binding constants for complexes 1-3 to bovine serum albumin (BSA) were found to be high enough to indicate their binding to this biomolecule, but not so high as to prevent their release upon arrival at the target site. Moreover, the positive values of partition coefficients for these complexes indicated their ability to be transported through the cell membrane. Once inside the cell, complexes 1-3 could induce the formation of the reactive oxygen species (ROS) in C. albicans cells and/or interact with DNA. Taken together, silver(i) complexes with the tpmc ligand could be considered as novel antimicrobial compounds with favourable pharmacological properties, being safer than AgSD.

Evaluation of Toxicity with Brine Shrimp Assay

The in vivo toxicity of new metallodrugs either as Small Bioactive Molecules (SBAMs) or Conjugates of Metals with Drugs (CoMeDs) or their hydrogels such as with hydroxyethyl-methacrylate (HEMA) (pHEMA@SBAMs or pHEMA@CoMeDs) are evaluated by the brine shrimp assay. Thus individuals of Artemia salina larvae are incubated in saline solutions with SBAMs, CoMeDs, pHEMA@SBAMs or pHEMA@CoMeDs or without for 24 h. The toxicity is then determined in terms of the mortality rate of brine shrimp larvae. Brine shrimp assay is a low cost, safe, no required feeding during the assay, while it requiring only a small amount of the tested agent.

Tetracycline Water Soluble Formulations with Enhanced Antimicrobial Activity

The negligible water solubility of tetracycline (TC), a well-known antibiotic of clinical use, is the major disadvantage for its oral administration. With the aim to improve the water solubility of TC, the micelles of formulae SLS@TC and CTAB@TC (SLS = sodium lauryl sulphate and CTAB = cetrimonium bromide) were synthesized. The micelles SLS@TC and CTAB@TC were characterized by melting point (m.p.), thermogravimetric differential thermal analysis (TG-DTA), differential scanning calorimetry (DTG/DSC), attenuated total reflection spectroscopy (FT-IR-ATR), ultra-violet visible (UV/vis) spectroscopy, proton nucleus magnetic resonance (1H-NMR) spectroscopy, and the ultrasonically-induced biregringence technique. The antimicrobial activity of SLS@TC and CTAB@TC was evaluated, by means of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and inhibition zone (IZ), against the Gram negative bacterial strains Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) and the Gram positive ones of the genus of Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus). Generally, both micelles show better activity than that of TC against the microbial strains tested. Thus, the MIC value of CTAB@TC is 550-fold higher than that of free TC against S. epidermidis. Despite the stronger activity of CTAB@TC than SLS@TC against both Gram negative and Gram positive microbes, SLS@TC is classified as a bactericidal agent (in that it eliminates 99.9% of the microbes), in contrast to CTAB@TC, which is bacteriostatic one (inhibits, but does not kill the organisms). The toxicity of SLS@TC and CTAB@TC was evaluated against human corneal eukaryotic cells (HCECs). Moreover, SLS@TC and CTAB@TC exhibit low in vivo toxicity against Artemia salina, even at concentrations up to threefold higher than those of their MICmax. Therefore, SLS@TC and CTAB@TC can be candidates for the development of new antibiotics.

Synthesis and antimicrobial evaluation of a pyrazoline-pyridine silver(I) complex: DNA-interaction and anti-biofilm activity

The emergence of resistant bacterial strains mainly due to misuse of antibiotics has seriously affected our ability to treat bacterial illness, and the development of new classes of potent antimicrobial agents is desperately needed. In this study, we report the efficient synthesis of a new pyrazoline-pyridine containing ligand L1 which acts as an NN-donor for the formation of a novel silver (I) complex 2. The free ligand did not show antibacterial activity. High potency was exhibited by the complex against three Gram-negative bacteria, namely Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumanii with the minimum inhibitory concentration (MIC) ranging between 4 and 16 μg/mL (4.2-16.7 μM), and excellent activity against the fungi Candida albicans and Cryptococcus neoformans (MIC ≤ 0.25 μg/mL = 0.26 μM). Moreover, no hemolytic activity within the tested concentration range was observed. In addition to the planktonic growth inhibition, the biofilm formation of both Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa was significantly reduced by the complex at MIC concentrations in a dose-dependent manner for Pseudomonas aeruginosa, whereas a biphasic response was obtained for MRSA showing that the sub-MIC doses enhanced biofilm formation before its reduction at higher concentration. Finally, complex 2 exhibited strong DNA binding with a large drop in DNA viscosity indicating the absence of classical intercalation and suggesting the participation of the silver ion in DNA binding which may be related to its antibacterial activity. Taken together, the current results reveal that the pyrazoline-pyridine silver complexes are of high interest as novel antibacterial agents, justifying further in vitro and in vivo investigation.

pHEMA@AGMNA-1: A novel material for the development of antibacterial contact lens

The Metal Organic Framework (MOF) of formula {[Ag₆(μ₃-HMNA)₄(μ₃-MNA)₂]^2-·[(Et₃NH)⁺]₂·(DMSO)₂·(H₂O)} (AGMNA), a known efficient antimicrobial compound which contains the anti-metabolite, 2-thio-nicotinic acid (H₂MNA), was incorporated in polymer hydrogels using, hydroxyethyl-methacrylate (HEMA). The material pHEMA@AGMNA-1 was characterized by X-ray fluorescence (XRF) spectroscopy, X-ray powder diffraction analysis (XRPD), Scanning Electron Microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), Thermogravimetric Differential Thermal Analysis (TG-DTA), Differential Scanning Calorimetry (DTG/DSC), attenuated total reflection spectroscopy (FT-IR-ATR) and Ultrasonic Imaging. The antimicrobial capacity of pHEMA@AGMNA-1 was evaluated against the Gram negative bacterial strain Pseudomonas aeruginosa and the Gram positive ones of the genus of Staphylococcus epidermidis and Staphylococcus aureus, which are the etiology of the microbial keratitis. The % bacterial viability of P. aeruginosa, S. epidermidis and S. aureus upon their incubation with pHEMA@AGMNA-1 discs is significantly low (0.4 ± 0.1%, 1.5 ± 0.4% and 7.7 ± 0.5% respectively). The inhibition zones (IZ) caused by pHEMA@AGMNA-1 discs against P. aeruginosa, S. epidermidis and S. aureus are 14.0 ± 1.1, 11.3 ± 1.3 and 11.8 ± 1.8 mm respectively. Furthermore, pHEMA@AGMNA-1 exhibits low toxicity. Thus, pHEMA@AGMNA-1 might be an efficient candidate for the development of antimicrobial active contact lenses.

Conjugation of Penicillin-G with Silver(I) Ions Expands Its Antimicrobial Activity against Gram Negative Bacteria

Conjugation of penicillin G (PenH) with silver(I) ions forms a new CoMeD (conjugate of metal with a drug) with formula [Ag(pen)(CH₃OH)]₂ (PenAg). PenAg was characterized by a plethora of physical and spectroscopic techniques, which include in the solid state m.p.; elemental analysis; X-ray fluorescence (XRF) spectroscopy; scanning electron microscopy (SEM); energy-dispersive X-ray spectroscopy (EDX); FT-IR; and in solution: attenuated total reflection spectroscopy (FT-IR-ATR), UV–Vis, ¹H NMR, and atomic absorption (AA). The structure of PenAg was determined by NMR spectroscopy. Silver(I) ions coordinate to the carboxylic group of PenH, while secondary intra-molecular interactions are developed through (i) the nitrogen atom of the amide group in MeOD-d₄ or (ii) the sulfur atom in the thietane ring in deuterated dimethyl sulfoxide DMSO-d₆. The antibacterial activities of PenAg and the sodium salt of penicillin (PenNa) (the formulation which is clinically used) against Gram positive (Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus)) and Gram negative (Pseudomonas aeruginosa (P. aeuroginosa PAO1)) bacteria were evaluated by the means of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and inhibition zone (IZ). PenAg inhibits the growth of the Gram negative bacterial strain P. aeuroginosa with a MIC value of 23.00 ± 2.29 μM, in contrast to PenNa, which shows no such activity (>2 mM). The corresponding antimicrobial activities of PenAg against the Gram positive bacteria S. epidermidis and S. aureus are even better than those of PenNa. Moreover, PenAg exhibits no in vivo toxicity against Artemia salina at concentration up to 300 μΜ. The wide therapeutic window and the low toxicity, make PenAg a possible candidate for the development of a new antibiotic.

Synthesis and dye adsorption studies of the {dibromo(1,1′-(1,2-ethanediyl)bis(3-methyl-imidazole-2-thione)dicopper(i)}n polymer and its conversion to CuO nanospheres for photocatalytic and antibacterial applications

A new copper polymer was used as a dye adsorbent and CuO precursor. The CuO nanospheres showed good performances for photocatalytic and antibacterial applications.

An Efficient Disinfectant, Composite Material {SLS@[Zn3(CitH)2]} as Ingredient for Development of Sterilized and Non Infectious Contact Lens

The [Zn₃(CitH)₂] (1) (CitH₄= citric acid), was dispersed in sodium lauryl sulphate (SLS) to form the micelle of SLS@[Zn₃(CitH)₂] (2). This material 2 was incorporated in hydrogel made by hydroxyethyl-methacrylate (HEMA), an ingredient of contact lenses, toward the formation of pHEMA@(SLS@[Zn₃(CitH)₂]) (3). Samples of 1 and 2 were characterized by UV-Vis, ¹H-NMR, FT-IR, FT-Raman, single crystal X-ray crystallography, X-ray fluorescence analysis, atomic absorption and TG/DTA/DSC. The antibacterial activity of 1–3 as well as of SLS against Gram-positive (Staphylococcus epidermidis (St. epidermidis) and Staphylococcus aureus (St. aureus)) and Gram-negative (Pseudomonas aeruginosa (PAO1), and Escherichia coli (E. coli)) bacteria was evaluated by the means of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and inhibitory zone (IZ). 2 showed 10 to 20-fold higher activity than 1 against the bacteria tested. Moreover the 3 decreases the abundance of Gram-positive microbes up to 30% (St. aureus) and up to 20% (PAO1) the Gram-negative ones. The noteworthy antimicrobial activity of the obtained composite 3 suggests an effective antimicrobial additive for infection-free contact lenses.

Evaluation of Genotoxicity by Micronucleus Assay in vitro and by Allium cepa Test in vivo

The in vitro and in vivo genotoxicity of new metallodrugs either as Small Bioactive Molecules (SBAMs) or Conjugates of Metals with Drugs (CoMeDs) is evaluated by the micronucleus test and the Allium cepa assay, respectively. Fetal lung fibroblast cells (MRC-5), normal human corneal epithelial cells (HCEC) and immortalized human keratinocytes cells (HaCaT) were incubated with solutions of SBAMs or CoMeDs at their IC₅₀ values for 48 h (the concentration of a compound which is required to inhibit the cells growth by 50% in relation to the non-treated cells). The micronucleus abundance percentage towards the corresponding one, of the non-treated cells indicates the in vitro genotoxicity of the formulations. The in vivo Allium cepa test comprises the exposing of the plant Allium cepa roots to an SBAMs or a CoMeDs solution for 48 h. The percentages of the mitotic index, the chromosome aberrations, the nuclear abnormalities and the presence of the micronucleus are calculated indicating the in vivo genotoxicity of the agent.

Silver derivatives of multi-donor heterocyclic thioamides as antimicrobial/anticancer agents: unusual bio-activity against methicillin resistantS. aureus,S. epidermidis, andE. faecalisand human bone cancerMG63cell line

A series of biosafe mixed-ligand complexes of silver with heterocyclic thioamides have been studied for their antimicrobial/anticancer activity.

Silver ciprofloxacin (CIPAG): a successful combination of chemically modified antibiotic in inorganic-organic hybrid

The new silver(I) ionic, water soluble, compound {[Ag(CIPH)₂]NO₃∙0.75MeOH∙1.2H₂O} (CIPAG) was obtained by reacting silver(I) nitrate with the antibiotic ciprofloxacin (CIPH). The complex was characterized by m.p., mid-FT-IR, ¹H-NMR, UV-Vis spectroscopic techniques. The crystal structures of both CIPAG and the hexahydrated neutral free drug {[CIPH]∙6(H₂O)} (2) were characterized by X-ray crystallography. Two neutral ligands are datively bonded to the metal ion through the piperidinic nitrogen atoms forming a cationic {[Ag(CIPH)₂]⁺} counter part which is neutralized by a nitrate group. The antibacterial effect of CIPAG and the commercially available hydrochloric salt of the antibiotic ({[CIPH ₂⁺ ]∙Cl ^- } (3)) were tested against the bacterial species Pseudomonas aeruginosa (PAO1), Staphylococcus epidermidis (St. epidermidis) and Staphylococcus aureus (St. aureus) by the mean of minimum inhibitory concentration, minimum bactericidal concentration and their inhibitory zone (IZ). The influence of CIPAG and 3 against the formation of biofilm of PAO1 or St. aureus was also evaluated by mean of biofilm elimination concentration. The IZ caused by CIPAG which has been loaded in poly-hydroxyethylmethacrylate, is determined. The genotoxicity of CIPAG and 3 is tested in vitro against normal human corneal epithelial cells (HCET cells), by the presence of micronucleus in HCET cells and in vivo by mean of Allium cepa test.

Silver complex of salicylic acid and its hydrogel-cream in wound healing chemotherapy

The known metallotherapeutic [Ag(salH)]₂ (AGSAL-1) of salicylic acid (salH₂), was used for the development of new efficient silver based material for wounds healing. AGSAL-1 was characterized by spectroscopic techniques and X-ray crystallography. The wound healing epithelialization of AGSAL-1 was investigated by the means of scratch assay against immortalized human keratinocytes (HaCaT) cells. The anti-inflammatory activity of AGSAL-1 was evaluated by monitoring the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX). The antibacterial activity of AGSAL-1 was evaluated against bacterial species which colonize wounds, such as: Pseudomonas aeruginosa (PAO1), Staphylococcus epidermidis and Staphylococcus aureus, by the means of Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) and their Inhibition Zone (IZ). Moreover, the influence of AGSAL-1 against the formation of biofilm of PAO1 and St. aureus was also evaluated by the mean of Biofilm Elimination Concentration (ΒΕC). A hydrogel material CMC@AGSAL-1, based on the dispersion of AGSAL-1 in to carboxymethyl cellulose (CMC) was tested for its antimicrobial activity. Molecular Docking was performed, to explore the molecular interaction of AGSAL-1 with (i) the transcriptional regulator of PAO1, LasR. (ii) the mevalonate pathway for the biosynthesis of isoprenoids which is essential for gram-positive bacteria St. epidermidis and St. aureus. The toxicity of AGSAL-1 was examined against the HaCaT cells. Its genotoxicity was evaluated using Allium cepa model, in vivo. No genotoxicity was detected, indicating that AGSAL-1 is a candidate towards the development on a new efficient medication of the silver based metallodrugs.

Synthesis, structures, and ESI-mass studies of silver(I) derivatives of imidazolidine-2-thiones: Antimicrobial potential and biosafety evaluation

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.

Synthesis, structures and biomolecular interactions of new silver(i) 5,5-diethylbarbiturate complexes of monophosphines targeting Gram-positive bacteria and breast cancer cells

New silver(i) 5,5-diethylbarbiturate complexes exhibit very high antimicrobial activity against Gram-positive bacteria and kill MCF-7 cells, damaging mitochondria and DNA.