Investigation on the pharmacological profile of 2,6-diacetylpyridine bis(benzoylhydrazone) derivatives and their antimony(III) and bismuth(III) complexes

Structural investigations and antibacterial, antifungal and anticancer studies on zinc salicylaldimine complexes

Aim: Zinc salicylaldimines may act as multidrug agents. Results: Three zinc salicylaldimines C1-C3 and respective ligands HL1-HL3 were examined for antimicrobial/anticancer drug action and C3 was structurally analyzed (tetrahedral, triclinic). Against two fungi, C1 inhibited Candida albicans with 12 mm (21 mm for amphotericin B). Among four bacteria, two ligands inhibited Staphylococcus aureus and Escherichia coli (9-10 mm), but the complexes inhibited all bacteria with 10-14 mm (21-26 mm for ampicillin). The half-maximal inhibitory concentrations for the ligands, complexes and doxorubicin were 195.5-310.7, 22.18-70.05 and 9.66 μM against cancerous MCF-7 cells and 186.4-199.9, 14.95-18.87 and 36.42 μM against normal BHK cells. Conclusion: The complexation produced pronounced enhancement in the ligand antimicrobial/anticancer activities, despite these activities are moderate comparing with standards.

Biological Activities of Bismuth Compounds: An Overview of the New Findings and the Old Challenges Not Yet Overcome

Bismuth-based drugs have been used primarily to treat ulcers caused by Helicobacter pylori and other gastrointestinal ailments. Combined with antibiotics, these drugs also possess synergistic activity, making them ideal for multiple therapy regimens and overcoming bacterial resistance. Compounds based on bismuth have a low cost, are safe for human use, and some of them are also effective against tumoral cells, leishmaniasis, fungi, and viruses. However, these compounds have limited bioavailability in physiological environments. As a result, there is a growing interest in developing new bismuth compounds and approaches to overcome this challenge. Considering the beneficial properties of bismuth and the importance of discovering new drugs, this review focused on the last decade's updates involving bismuth compounds, especially those with potent activity and low toxicity, desirable characteristics for developing new drugs. In addition, bismuth-based compounds with dual activity were also highlighted, as well as their modes of action and structure-activity relationship, among other relevant discoveries. In this way, we hope this review provides a fertile ground for rationalizing new bismuth-based drugs.

In vitro biological activity of cobalt(II) complexes with salicylaldimine ligands in microbial and cancer cells

Background: More studies using cobalt complexes as drugs are needed. Results: The drug action of two cobalt salicylaldimines was determined. The complexes and amphotericin B (20 mg/ml) inhibited Candida albicans at 9-15 and 21 mm. This concentration of both ligands inhibited Staphylococcus aureus at 10 mm and one ligand inhibited Escherichia coli at 9 mm, but the complexes and ampicillin inhibited four bacteria at 9-20 and 21-26 mm. The ligands were inactive against cancer and normal cells, but the complexes and doxorubicin provided IC50 values of 28.18-54.19 and 9.66 μM against MCF-7 cells and 15.76-20.49 and 36.42 μM against BHK cells. Conclusion: The ligands' activity was much improved by complexation, although they remained substandard.

Thiosemicarbazones and Derived Antimony Complexes: Synthesis, Structural Analysis, and In Vitro Evaluation against Bacterial, Fungal, and Cancer Cells

Two antimony complexes {[Sb(L1)Cl2] C1 and [Sb(L2)Cl2] C2} with the thiosemicarbazone ligands {HL1 = 4-(2,4-dimethylphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were introduced. The structures were elucidated on the basis of a CHNS analysis, spectroscopic techniques (UV-Vis and FT-IR), and DMF solution electrical conductivities. Single crystal X-ray diffraction analysis of complex C1 assigned the complex pseudo-octahedral geometry and triclinic P-1 space group. Only the ligand HL1 and its derived complex C1 displayed antifungal activities against Candida albicans and this activity was enhanced from 10 mm to 21 mm for the respective complex, which is the same activity given by the drug “Amphotericin B”. The ligands HL1 and HL2 gave inhibitions, respectively, of 14 and 10 mm against Staphylococcus aureus and 15 and 10 mm against Escherichia coli; however, complexes C1 and C2 increased these inhibitions to 36 and 32 mm against Staphylococcus aureus and 35 and 31 mm against Escherichia coli exceeding the activities given by the ampicillin standard (i.e., 21 mm against Staphylococcus aureus and 25 mm against Escherichia coli). Against MCF-7 human breast cancer cells, the IC50 values of HL1 (68.9 μM) and HL2 (145.4 μM) were notably enhanced to the values of 34.7 and 37.4 μM for both complexes, respectively. Further, the complexes induced less toxicity in normal BHK cells (HL1 (126.6 μM), HL2 (110.6 μM), C1 (>210.1 μM), and C2 (160.6 μM)). As a comparison, doxorubicin gave an IC50 value of 9.66 μM against MCF-7 cells and 36.42 μM against BHK cells.

Trivalent Cobalt Complexes with NNS Tridentate Thiosemicarbazones: Preparation, Structural Study and Investigation of Antibacterial Activity and Cytotoxicity against Human Breast Cancer Cells

New complexes of trivalent cobalt with substituted thiosemicarbazone ligands having an NNS donor system {HL1 = 4-(4-nitrophenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide and HL2 = 4-(2,5-dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide} were synthesized via the in situ oxidation of divalent cobalt chloride accompanying its addition to the ligands. The complexes C1 and C2 were characterized via elemental (CHNS) analysis and 1H NMR, FT-IR and UV-Vis. spectroscopic data. Further, conductometric studies on the DMF solutions of the complexes indicated their 1:1 nature, and their diamagnetism revealed the low-spin trivalent oxidation state of the cobalt in the complexes. The X-ray diffraction analysis of complex C1 indicated that it crystallizes in the triclinic space group P-1. The metal exhibits an octahedral environment built by two anionic ligands bound via pyridine nitrogen, imine nitrogen and thiol sulfur atoms. The complex is counterbalanced by a chloride ion. In addition, two lattice water molecules were detected in the asymmetric unit of the unit cell. The ligand HL2 (20 mg/mL in DMSO) displayed inhibition zones of 10 mm against both S. aureus and E. coli, and the same concentration of the respective complex raised this activity to 15 and 12 mm against these bacterial strains, respectively. As a comparison, ampicillin inhibited these bacterial strains by 21 and 25 mm, respectively. Screening assay by HL1 on four human cancer cells revealed the most enhanced activity against the breast MCF-7 cells. The induced growth inhibitions in the MCF-7 cells by all compounds (0–100 μg/mL) have been detected. The ligands {HL1 and HL2} and complex C2 gave inhibitions with IC50 values of 52.4, 145.4 and 49.9 μM, respectively. These results are more meaningful in comparison with similar cobalt complexes, but less efficient compared with the inhibition with IC50 of 9.66 μM afforded by doxorubicin. In addition, doxorubicin, HL1 and HL2 induced cytotoxicity towards healthy BHK cells with IC50 values of 36.42, 54.8 and 110.6 μM, but surviving fractions of 66.1% and 62.7% of these cells were detected corresponding to a concentration of 100 μg/mL of the complexes (136.8 μM of C1 and 131.4 μM of C2).

Pincer Complexes Derived from Tridentate Schiff Bases for Their Use as Antimicrobial Metallopharmaceuticals

Within the current challenges in medicinal chemistry, the development of new and better therapeutic agents effective against infectious diseases produced by bacteria, fungi, viruses, and parasites stands out. With chemotherapy as one of the main strategies against these diseases focusing on the administration of organic and inorganic drugs, the latter is generally based on the synergistic effect produced by the formation of metal complexes with biologically active organic compounds. In this sense, Schiff bases (SBs) represent and ideal ligand scaffold since they have demonstrated a broad spectrum of antitumor, antiviral, antimicrobial, and anti-inflammatory activities, among others. In addition, SBs are synthesized in an easy manner from one-step condensation reactions, being thus suitable for facile structural modifications, having the imine group as a coordination point found in most of their metal complexes, and promoting chelation when other donor atoms are three, four, or five bonds apart. However, despite the wide variety of metal complexes found in the literature using this type of ligands, only a handful of them include on their structures tridentate SBs ligands and their biological evaluation has been explored. Hence, this review summarizes the most important antimicrobial activity results reported this far for pincer-type complexes (main group and d-block) derived from SBs tridentate ligands.

Synthesis, characterization, antimicrobial and cytotoxic activity and DNA-binding properties of d-metal complexes with hydrazones of Girard's T and P reagents

In this work synthesis, characterization and crystal structures of 1, Zn(II) complex ([ZnL¹(NCS)₂]), with (E)-1-(2-oxo-2-(2-(quinolin-2-ylmethylene)hydrazinyl)ethyl)pyridin-1-ium chloride (HL¹Cl) and 2, Bi(III) complex ([BiHL²Cl₄] × 1/2CH₃OH), with (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(thiazol-2-yl)ethylidene)hydrazinyl)ethan-1-aminium chloride (HL²Cl), have been reported. Zn(II) complex possesses a distorted trigonal bipyramidal geometry while surroundings around Bi(III) ion are extended pentagonal bipyramidal. Antimicrobial activity, brine shrimp assay and DPPH radical scavenging activity of both complexes, including previously synthesized complexes with HL²Cl ligand (Zn(II) and Ni(II)) and complexes with (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium chloride (HL³Cl) (Zn(II), Cu(II), Cd(II), Co(II), Fe(III), Ni(II)), were evaluated. For the most active complexes, cytotoxic activity against five malignant cancer cell lines (HeLa, A375, MCF7, PC-3 and A549) and normal cell line HaCaT, as well as generation of reactive oxygen species (ROS), was tested.

Dual anticancer and antibacterial activities of bismuth compounds based on asymmetric [NN'O] ligands

Two new bismuth(III) complexes, [BiL¹Cl₂] (1) and [BiL²Cl₂] (2), in which L¹ is (2-hydroxy-4-6-di-tert-butylbenzyl-2-pyridylmethyl)amine and L² is 2,4-diiodo-6-((pyridine-2-ylmethylamino)methyl)phenol, were synthesized and characterized by elemental and conductivity analyses, atomic absorption spectrometry, infrared and ¹H NMR spectroscopies. The molecular structure of 1 reveals that the NN'O ligand forms a 1:1 complex with bismuth through coordination via the nitrogen of the aliphatic amine, the nitrogen of the pyridine ring and the oxygen of the phenolate. The coordination sphere is completed with two chloride anions in a distorted square pyramidal geometry. Bismuth exhibits the same coordination mode in compound 2. The cytotoxic activity of 1 and 2 was investigated in a chronic myelogenous leukemia cell line. The complexes are approximately three times more potent than the corresponding free ligands, with the IC₅₀ values 0.30 and 0.38 μM for complex 1 and 2, respectively. To address the cellular mechanisms underlying cell demise, apoptosis was quantified by flow cytometry analysis. From 0.1 μM, both complexes induce apoptosis and there is a remarkable concentration-dependent increase in the population of cells in apoptosis. The complexes were also evaluated against Gram-positive and Gram-negative bacteria. Both inhibited the bacterial growth in a concentration-dependent way, with remarkable activity in some of the tested strains, for example, complex 2 was more active than its free ligand against all bacterial strains and approximately fourteen times more potent against S. dysenteriae and S. typhimurium.

Bismuth-213 for Targeted Radionuclide Therapy: From Atom to Bedside

In contrast to external high energy photon or proton therapy, targeted radionuclide therapy (TRNT) is a systemic cancer treatment allowing targeted irradiation of a primary tumor and all its metastases, resulting in less collateral damage to normal tissues. The α-emitting radionuclide bismuth-213 (213Bi) has interesting properties and can be considered as a magic bullet for TRNT. The benefits and drawbacks of targeted alpha therapy with 213Bi are discussed in this review, covering the entire chain from radionuclide production to bedside. First, the radionuclide properties and production of 225Ac and its daughter 213Bi are discussed, followed by the fundamental chemical properties of bismuth. Next, an overview of available acyclic and macrocyclic bifunctional chelators for bismuth and general considerations for designing a 213Bi-radiopharmaceutical are provided. Finally, we provide an overview of preclinical and clinical studies involving 213Bi-radiopharmaceuticals, as well as the future perspectives of this promising cancer treatment option.

New Antimicrobial Strategies Based on Metal Complexes

Traditional organic antimicrobials mainly act on specific biochemical processes such as replication, transcription and translation. However, the emergence and wide spread of microbial resistance is a growing threat for human beings. Therefore, it is highly necessary to design strategies for the development of new drugs in order to target multiple cellular processes that should improve their efficiency against several microorganisms, including bacteria, viruses or fungi. The present review is focused on recent advances and findings of new antimicrobial strategies based on metal complexes. Recent studies indicate that some metal ions cause different types of damages to microbial cells as a result of membrane degradation, protein dysfunction and oxidative stress. These unique modes of action, combined with the wide range of three-dimensional geometries that metal complexes can adopt, make them suitable for the development of new antimicrobial drugs.

Organoantimony(III) halide complexes with azastibocine framework as potential antitumor agents: Correlation between cytotoxic activity and N→Sb inter-coordination

The relationship between chemical structure and in vitro cytotoxic activities of a series of azastibocine-framework organoantimony(III) halide complexes against cancerous (HepG2, MDA-MB-231, MCF-7 and HeLa) and nonmalignant (HEK-293) cell lines was studied for the first time. A positive correlation between cytotoxic activity and the length of N→Sb coordinate bond on azastibocine framework of same nitrogen substituent was observed. By comparison, the organoantimony(III) complex 6-cyclohexyl-12-fluoro-5,6,7,12-tetrahydrodibenzo[c,f][1,5]azastibocine (C4) exhibited the highest selectivity index, giving a IC₅₀(nonmalignant)/IC₅₀(cancerous) ratio of up to 8.33. The results of cell cycle analysis indicated that the inhibitory effect of C4 on the cellular viability was caused by cell cycle arrest mainly at the S phase. The necrosis induced by C4 was confirmed by the Trypan blue dye exclusion test and the increase of lactic dehydrogenase (LDH) released in the culture medium. Furthermore, evaluation of the levels of intracellular reactive oxygen species (ROS) in MDA-MB-231 cells, by quantifying the relative fluorescence units (RFU) using spectrofluorometer, indicated that cytotoxic activity of C4 is dependent on the production of ROS. This work established the correlation between cytotoxic activity and N→Sb inter-coordination, a finding that provided theoretical and experimental basis for in-depth design of antimony-based organometallic complexes as potential anticancer agents.

Recent Research Trends on Bismuth Compounds in Cancer Chemoand Radiotherapy

Background:

Application of coordination chemistry in nanotechnology is a rapidly developing research field in medicine. Bismuth complexes have been widely used in biomedicine with satisfactory therapeutic effects, mostly in Helicobacter pylori eradication, but also as potential antimicrobial and anti-leishmanial agents. Additionally, in recent years, application of bismuth-based compounds as potent anticancer drugs has been studied extensively.

Methods:

Search for data connected with recent trends on bismuth compounds in cancer chemo- and radiotherapy was carried out using web-based literature searching tools such as ScienceDirect, Springer, Royal Society of Chemistry, American Chemical Society and Wiley. Pertinent literature is covered up to 2016.

Results:

In this review, based on 213 papers, we highlighted a number of current problems connected with: (i) characterization of bismuth complexes with selected thiosemicarbazone, hydrazone, and dithiocarbamate classes of ligands as potential chemotherapeutics. Literature results derived from 50 papers show that almost all bismuth compounds inhibit growth and proliferation of breast, colon, ovarian, lung, and other tumours; (ii) pioneering research on application of bismuth-based nanoparticles and nanodots for radiosensitization. Results show great promise for improvement in therapeutic efficacy of ionizing radiation in advanced radiotherapy (described in 36 papers); and (iii) research challenges in using bismuth radionuclides in targeted radioimmunotherapy, connected with choice of adequate radionuclide, targeting vector, proper bifunctional ligand and problems with 213Bi recoil daughters toxicity (derived from 92 papers).

Conclusion:

This review presents recent research trends on bismuth compounds in cancer chemo- and radiotherapy, suggesting directions for future research.

Investigation of the antitrypanosomal effects of 2-formyl-8-hydroxyquinoline-derived hydrazones and their antimony(iii) and bismuth(iii) complexes

2-formyl-8-hydroxyquinoline-4-nitroimidazolhydrazone (H2Q4NO₂Im, H2La, 1) and 2-formyl-8-hydroxyquinoline-4-nitrobenzenehydrazone (H2Q4NO₂Ph, H2Lb, 2) were obtained, as well as their Sb(iii) [Sb(L)Cl₂] (3, 4) and Bi(III) [Bi(L)Cl₂] (5, 6) complexes.

In vitro evaluation of the antitumor effect of bismuth lipophilic nanoparticles (BisBAL NPs) on breast cancer cells

Aim

The objective of this study was to evaluate the antitumor activity of lipophilic bismuth nanoparticles (BisBAL NPs) on breast cancer cells.

Materials and methods

The effect of varying concentrations of BisBAL NPs was evaluated on human MCF-7 breast cancer cells and on MCF-10A fibrocystic mammary epitheliocytes as noncancer control cells. Cell viability was evaluated with the MTT assay, plasma membrane integrity was analyzed with the calcein AM assay, genotoxicity with the comet assay, and apoptosis with the Annexin V/7-AAD assay.

Results

BisBAL NPs were spherical in shape (average diameter, 28 nm) and agglomerated into dense electronic clusters. BisBAL NP induced a dose-dependent growth inhibition. Most importantly, growth inhibition was higher for MCF-7 cells than for MCF-10A cells. At 1 µM BisBAL NP, MCF-7 growth inhibition was 51%, while it was 11% for MCF-10A; at 25 µM BisBAL NP, the growth inhibition was 81% for MCF-7 and 24% for MCF-10A. With respect to mechanisms of action, a 24-hour exposure of 10 and 100 µM BisBAL NP caused loss of cell membrane integrity and fragmentation of tumor cell DNA. BisBAL NPs at 10 µM were genotoxic to and caused apoptosis of breast cancer cells.

Conclusion

BisBAL NP-induced growth inhibition is dose dependent, and breast cancer cells are more vulnerable than noncancer breast cells. The mechanism of action of BisBAL NPs may include loss of plasma membrane integrity and a genotoxic effect on the genomic DNA of breast cancer cells.

Emerging Nanomedicine Therapies to Counter the Rise of Methicillin-Resistant Staphylococcus aureus

In a recent report, the World Health Organisation (WHO) classified antibiotic resistance as one of the greatest threats to global health, food security, and development. Methicillin-resistant Staphylococcus aureus (MRSA) remains at the core of this threat, with persistent and resilient strains detectable in up to 90% of S. aureus infections. Unfortunately, there is a lack of novel antibiotics reaching the clinic to address the significant morbidity and mortality that MRSA is responsible for. Recently, nanomedicine strategies have emerged as a promising therapy to combat the rise of MRSA. However, these approaches have been wide-ranging in design, with few attempts to compare studies across scientific and clinical disciplines. This review seeks to reconcile this discrepancy in the literature, with specific focus on the mechanisms of MRSA infection and how they can be exploited by bioactive molecules that are delivered by nanomedicines, in addition to utilisation of the nanomaterials themselves as antibacterial agents. Finally, we discuss targeting MRSA biofilms using nano-patterning technologies and comment on future opportunities and challenges for MRSA treatment using nanomedicine.

Synthesis, characterization and crystal structures of two pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent. Anticancer properties of various metal complexes of the same ligand

In this work synthesis, characterization and crystal structures of two isothiocyanato Fe(III) complexes with 2,2'-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2-ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] dichloride (H₂LCl₂) ligand, with composition [FeL(NCS)₂]SCN·2H₂O and [FeL(NCS)₂]₂[Fe(H₂O)(NCS)₅]·4H₂O, has been reported. Both iron(III) complexes possess the same pentagonal-bipyramidal complex cation, while the nature of their anions depends on mole ratio of NH₄SCN and FeCl₃·6H₂O used in reaction. Cytotoxic activity of new Fe(III) complexes, as well as of previously synthesized isothiocyanato Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand, was tested against five human cancer cell lines (HeLa, MDA-MB-453, K562, LS174 and A549) and normal cell line MRC-5. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes. The investigation of potential of these complexes to induce HeLa and K562 cell cycle perturbations was also evaluated. Mechanism of cell death mode was elucidated on the basis of morphological changes of HeLa cells as well as identification of target caspases. It was established that DNA damage could be responsible for the activity of Fe(III) and Co(II) complexes.

SYNOPSIS

Pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent have been synthesized and characterized. Cytotoxic activity of Fe(III) complexes and Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand was tested. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes.

Potent anticancer activity of a new bismuth (III) complex against human lung cancer cells

The aim of this work is experimental study of an interesting bismuth(III) complex derived from pentadentate 2,6-pyridinedicarboxaldehyde bis(⁴N-methylthiosemicarbazone), [BiL(NO₃)₂]NO₃ {L=2,6-pyridinedicarboxaldehyde bis(⁴N-methylthiosemicarbazone)}. A series of in vitro biological studies indicate that the newly prepared [BiL(NO₃)₂]NO₃ greatly suppressed colony formation, migration and significantly induced apoptosis of human lung cancer cells A549 and H460, but did not obviously decrease the cell viability of non-cancerous human lung fibroblast (HLF) cell line, showing much higher anticancer activities than its parent ligands, especially with half maximum inhibitory concentration (IC₅₀) <3.5μM. Moreover, in vivo study provides enough evidence that the treatment with [BiL(NO₃)₂]NO₃ effectively inhibited A549 xenograft tumor growth on tumor-bearing mice (10mgkg^-1, tumor volume reduced by 97.92% and tumor weight lightened by 94.44% compared to control) and did not indicate harmful effect on mouse weight and liver. These results suggest that the coordination of free ligand with Bi(III) might be an interesting and potent strategy in the discovery of new anticancer drug candidates.

Schiff bases in medicinal chemistry: a patent review (2010-2015)

INTRODUCTION

Schiff bases are synthetically accessible and structurally diverse compounds, typically obtained by facile condensation between an aldehyde, or a ketone with primary amines. Schiff bases contain an azomethine (-C = N-) linkage that stitches together two or more biologically active aromatic/heterocyclic scaffolds to form various molecular hybrids with interesting biological properties. Schiff bases are versatile metal complexing agents and have been known to coordinate all metals to form stable metal complexes with vast therapeutic applications. Areas covered: This review aims to provide a comprehensive overview of the various patented therapeutic applications of Schiff bases and their metal complexes from 2010 to 2015. Expert opinion: Schiff bases are a popular class of compounds with interesting biological properties. Schiff bases are also versatile metal complexing ligands and have been used to coordinate almost all d-block metals as well as lanthanides. Therapeutically, Schiff bases and their metal complexes have been reported to exhibit a wide range of biological activities such as antibacterial including antimycobacterial, antifungal, antiviral, antimalarial, antiinflammatory, antioxidant, pesticidal, cytotoxic, enzyme inhibitory, and anticancer including DNA damage.

Bismuth(III) complexes with 2-acetylpyridine- and 2-benzoylpyridine-derived hydrazones: Antimicrobial and cytotoxic activities and effects on the clonogenic survival of human solid tumor cells

Complexes [Bi(2AcPh)Cl2]·0.5H2O (1), [Bi(2AcpClPh)Cl2] (2), [Bi(2AcpNO2Ph)Cl2] (3), [Bi(2AcpOHPh)Cl2]·2H2O (4), [Bi(H2BzPh)Cl3]·2H2O (5), [Bi(H2BzpClPh)Cl3] (6), [Bi(2BzpNO2Ph)Cl2]·2H2O (7) and [Bi(H2BzpOHPh)Cl3]·2H2O (8) were obtained with 2-acetylpyridine phenylhydrazone (H2AcPh), its -para-chloro-phenyl- (H2AcpClPh), -para-nitro-phenyl (H2AcpNO2Ph) and -para-hydroxy-phenyl (H2AcpOHPh) derivatives, as well as with the 2-benzoylpyridine phenylhydrazone analogues (H2BzPh, H2BzpClPh, H2BzpNO2Ph, H2BzpOHPh). Upon coordination to bismuth(III) antibacterial activity against Gram-positive and Gram-negative bacterial strains significantly improved except for complex (4). The cytotoxic effects of the compounds under study were evaluated on HL-60, Jurkat and THP-1 leukemia, and on MCF-7 and HCT-116 solid tumor cells, as well as on non-malignant Vero cells. In general, 2-acetylpyridine-derived hydrazones proved to be more potent and more selective as cytotoxic agents than the corresponding 2-benzoylpyridine-derived counterparts. Exposure of HCT-116 cells to H2AcpClPh, H2AcpNO2Ph and complex (3) led to 99% decrease of the clonogenic survival. The IC50 values of these compounds were three-fold smaller when cells were cultured in soft-agar (3D) than when cells were cultured in monolayer (2D), suggesting that they constitute interesting scaffolds, which should be considered in further studies aiming to develop new drug candidates for the treatment of colon cancer.

The importance of Au⋯π(aryl) interactions in the formation of spherical aggregates in binuclear phosphane gold(i) complexes of a bipodal thiocarbamate dianion: a combined crystallographic and computational study, and anti-microbial activity

Compact molecular structures of antimicrobial (R₃PAu)₂L (R = Et (1), Ph ((2) and Cy ((3); LH₂ = {1,4-[MeOC(S)-N(H)]₂C₆H₄}), arise from intramolecular Au⋯π(aryl) interactions, proven by theory to be attractive and 12 kcal mol^–1 more stable than anticipated Au⋯O interactions.

Current and potential applications of bismuth-based drugs

: Bismuth compounds have been used extensively as medicines and in particular for the treatment of gastrointestinal ailments. In addition to bismuth's well known gastroprotective effects and efficacy in treating H. pylori infection it also has broad anti-microbial, anti-leishmanial and anti-cancer properties. Aspects of the biological chemistry of bismuth are discussed and biomolecular targets associated with bismuth treatment are highlighted. This review strives to provide the reader with an up to date account of bismuth-based drugs currently used to treat patients and discuss potential medicinal applications of bismuth drugs with reference to recent developments in the literature. Ultimately this review aims to encourage original contributions to this exciting and important field.