Structural characterization and antileishmanial activity of newly synthesized organo-bismuth(V) carboxylates: experimental and molecular docking studies.

In a quest to discover new formulations for the treatment of various parasitic diseases, a series of heteroleptic triorganobismuth(V) biscarboxylates of type [BiR3(O2CR')2], where R=C6H5 for 1-4 and p-CH3C6H4 for 5-8, were synthesized, characterized and evaluated for their biological potential against L. tropica. All the synthesized complexes were fully characterized by elemental analysis, FT-IR, multinuclear (1H and 13C) NMR spectroscopy and X-ray crystallography. The crystal structures for [BiPh3(O2CC6H4(o-Br))2] (1), [BiPh3(O2CC2H2C6H4)2] (2), [BiPh3(O2CC6H4(m-NO2))2] (3) and [BiPh3(O2CC6H4(2-OH,3-CH3))2] (4) were determined and found to have a distorted pentagonal bipyramidal molecular geometry with seven coordinated bismuth center for 1-3 and for 4 distorted octahedral geometry, respectively. All the synthesized complexes demonstrated a moderate to significant activity against leishmania parasites. A broad analytical approach was followed to testify the stability for (1-8) in solid state as well as in solution and in leishmanial culture M199, ensuring them to be stable enough to exert a significant antileishmanial effect with promising results. Cytotoxicity profile suggests that tris(tolyl) derivatives show lower toxicity against isolated lymphocytes with higher antileishmanial potential. Molecular docking studies were carried out to reveal the binding modes for (1-8) targeting the active site of trypanothione reductase (TR) (PDB ID: 4APN) and Trypanothione Synthetase-Amidase structure (PDB ID 2vob).

Solution-phase microwave assisted parallel synthesis, biological evaluation and in silico docking studies of N,N'-disubstituted thioureas derived from 3-chlorobenzoic acid.

A facile and robust microwave-assisted solution phase parallel synthesis protocol was exercised for the development of a 38-member library of N,N'-disubstituted thiourea analogues (1-38) by using an identical set of conditions. The reaction time for synthesis of N,N'-disubstituted thiourea analogues was drastically reduced from a reported duration of 8-12h for conventional methods to only 1.5-2.0min. All the derivatives (1-38) were characterized by physico-analytical techniques such as elemental analysis in combination with FT-IR, (1)H, (13)C NMR and by single crystal XRD analysis have also been performed. These compounds were screened for their in vitro urease inhibition activities. Majority of compounds exhibited potent urease inhibition activities, however, the most significant activity was found for 16, with an IC50 value of 1.23±0.1µM. Furthermore, the synthesized compounds were screened for their cytotoxic potential against lungs cancer cell lines. Cell culture studies demonstrated significant toxicity of the compounds on the cell lines, and the levels of toxicity were altered in the presence of various side groups. The molecular docking studies of the most potent inhibitors were performed to identify the probable binding modes in the active site of the urease enzymes. These compounds have a great potential and significance for further investigations.

Antileishmanial, DNA Interaction, and Docking Studies of Some Ferrocene-Based Heteroleptic Pentavalent Antimonials.

A series of ferrocenyl pentavalent antimonials (1-8) were synthesized and characterized by elemental analysis, FT-IR, and multinuclear ((1) H and (13) C) NMR spectroscopy. These antimonials were evaluated for their antileishmanial potential against Leishmania tropica KWH23, and by biocompatibility and membrane permeability assays. Moreover, mechanistic studies were carried out, mediated by DNA targeting followed by computational docking of ferrocenyl antimonials against the leishmanial trypanothione reductase enzyme. It was observed that the antimonials 1-8 were 390-fold more efficacious (IC50 ) as compared with the standard antimonial drug used. Cytotoxicity results showed that these antimonials are highly active even at low concentrations and are biocompatible with human macrophages. Antimonials 1-8 exhibited extensive intercalation with DNA and, furthermore, docking interactions highlighted the potential interactive binding of the anitimonials within the trypanothione reductase active site, with van der Waals interactions contributing significantly to the process. Hence, it is suggested that the reported antimonials demonstrate high efficacy, less toxicity, and target multiple sites of the Leishmania parasite.

Synthesis, characterization and urease inhibition, in vitro anticancer and antileishmanial studies of Ni(II) complexes with N,N,N'-trisubstituted thioureas.

A series of N,N,N'-trisubstituted thioureas (1-12) and their Ni(II) complexes (1a-12a) were synthesized and characterized by multinuclear ((1)H and (13)C) NMR, FT-IR spectroscopy and LC-MS techniques in combination with elemental analysis. The crystal structures of both ligands and Ni(II) chelates of type Ni(L-O, S)2 were determined by single crystal X-ray diffraction analysis. All the complexes were adopted to have square planar geometry, where the N,N,N'-trisubstituted thioureas showed bidentate mode of coordination at nickel centre through oxygen and sulfur atoms. The synthesized complexes were screened for potential inhibitors of Jack bean urease. Compounds 1a and 3a were observed as most potent inhibitors of urease exhibiting IC50 values of 1.17 ± 0.12 and 1.19 ± 0.41 µM, respectively. Cytotoxicity assay on lung carcinoma (H-157) and kidney fibroblast (BHK-21) cell showed that compounds were significant anticancer agents. Additionally, the complexes were tested against Leishmania major and found to be potent antileishmanial agents.

Effective utilization of magnetic nano-coupled cloned ß-xylanase in saccharification process.

The ß-xylanase gene (DCE06_04615) with 1041 bp cloned from Thermotoga naphthophila was expressed into E. coli BL21 DE3. The cloned ß-xylanase was covalently bound to iron oxide magnetic nanoparticles coated with silica utilizing carbodiimide. The size of the immobilized MNPs (50 nm) and their binding with ß-xylanase were characterized by Fourier-transform electron microscopy (FTIR) (a change in shift particularly from C-O to C-N) and transmission electron microscopy (TEM) (spherical in shape and 50 nm in diameter). The results showed that enzyme activity (4.5 ± 0.23 U per mL), thermo-stability (90 °C after 4 hours, residual activity of enzyme calculated as 29.89% ± 0.72), pH stability (91% ± 1.91 at pH 7), metal ion stability (57% ± 1.08 increase with Ca2+), reusability (13 times) and storage stability (96 days storage at 4 °C) of the immobilized ß-xylanase was effective and superior. The immobilized ß-xylanase exhibited maximal enzyme activity at pH 7 and 90 °C. Repeated enzyme assay and saccharification of pretreated rice straw showed that the MNP-enzyme complex exhibited 56% ± 0.76 and 11% ± 0.56 residual activity after 8 times and 13 times repeated usage. The MNP-enzyme complex showed 17.32% and 15.52% saccharification percentage after 1st and 8th time usage respectively. Immobilized ß-xylanase exhibited 96% residual activity on 96 days' storage at 4 °C that showed excellent stability.

Exploring biologically active hybrid pharmacophore N-substituted hydrazine-carbothioamides for urease inhibition: In vitro and in silico approach.

Urease is potential target for various human's health complications, such as peptic ulcer, gastric cancer and kidney stone formation. The present study was based on synthesis of new hybrid pharmacophore N-substituted hydrazine-carbothioamides as potential urease inhibitors. Presented method gave excellent yield in range of 85-95% for hydrazine-carbothioamides derivatives (3a-s) after reaction of mono- and disubstituted hydrazides (1a-k) and substituted isothiocyanates (2a-d). All newly derivatives were characterized by advanced spectroscopic techniques (FTIR, 1HNMR, 13CNMR, EMS) and were assessed for their urease inhibition potential. All analogs except for 3k, 3l and 3m demonstrated strong inhibitory potential for urease with IC50 values of 8.45 ± 0.14 to 25.72 ± 0.23 µM as compared to standard thiourea (IC50 21.26 ± 0.35 µM). The structure-activity relationship and mode of interaction was established by molecular docking studies. It was revealed that the N-substituted hydrazine-carbothioamides interacted with nickel atoms present in the active site of urease and supported the correlations with the experimental findings. Therefore, the afforded hydrazine-carbothioamides derivatives are interesting hits for urease inhibition studies with future prospects of modification and optimization.

Structure-activity relationships of new Organotin(IV) anticancer agents and their cytotoxicity profile on HL-60, MCF-7 and HeLa human cancer cell lines.

There is a growing interest in the cancer cell growth inhibitory effects of organotin (IV) compounds and, accordingly, a new series of dimethyl-, di-(n-butyl)-, diphenyl- and chloro-phenyl tin(IV) complexes with a Schiff base core were prepared. Their binding to DNA was assessed by UV thermal denaturation showing no interaction and by UV-vis titration exhibiting moderate interaction by intercalation. Complexes having n-butyl substituents were more potent and cytotoxic against human leukemia, breast and cervical cancer cell lines than other organotin(IV) complexes tested. Unfortunately, some of these compounds showed similar cytotoxicity in a non-cancerous cell line. We may conclude that cytotoxic activity was dependent on the nature (lipophilicity and size, according to the structure-activity relationship studies) and substitution pattern on the different structures. These results may aid in the rational design of metallodrugs, expanding the scope of organotin complexes in formulating new metal based drugs with dibutyl moieties.

Synthesis, characterization, DNA binding and in vitro antimicrobial studies of a novel tetra-substituted N-isopropyl-N-(4-ferrocenylphenyl)-N'-(2,6-diethylphenyl)-N″-benzoylguanidine: crystallographic structure and quantum chemical computations.

A novel tetra-substituted guanidine, N-isopropyl-N-(4-ferrocenylphenyl)-N'-(2,6-diethylphenyl)-N″-benzoylguanidine (1), [(CH3)2CH)(C5H5FeC5H4C6H4)NC(NHCOC6H5)(NHC6H3(CH2CH3)2] has been synthesized and characterized by elemental analysis, FT-IR, multinuclear ((1)H, (13)C) NMR spectroscopy, single crystal X-rays diffraction analysis and density functional theory based quantum chemical calculations. The torsion angles indicating that the guanidine moiety and carbonyl group are almost co-planar, due to the pseudo hexagonal ring formed by intramolecular N-H⋯O hydrogen bonds. The DNA interaction studies performed by cyclic voltammetry and UV-visible spectroscopy are in close agreement with the binding constants (K) 1.4×10(4) and 1.2×10(4) respectively. The shift in peak potential, current and absorption maxima of the studied ferrocenyl guanidine in the presence of DNA discovered that CV coupled with UV-vis spectroscopy could provide an opportunity to elaborate DNA interaction mechanism, a prerequisite for the design of new drug like agents and understanding the molecular basis of their action. The synthesized compound (1) has also been screened for their antibacterial and antifungal.

Novel approaches to screening guanidine derivatives.

INTRODUCTION: Compounds containing guanidine moiety, originating both from natural and synthetic sources, have found potential applications in both synthetic and medicinal chemistry. Indeed, guanidine functionality can be found in many natural and pharmaceutical products as well as in cosmetic ingredients produced by synthetic methods. AREAS COVERED: This review covers the latest developments in the research undertaken for the therapeutic application of newly synthesized guanidine derivatives including: small peptides and peptidomimetics. This article encompasses the selected literature published in the last three decades with a focus on the novel approaches for screening of lead drug candidates with their pharmacological action. EXPERT OPINION: Guanidines, as they are both organically based and also hydrophilic in nature, have undergone a mammoth amount of screening and testing to discover promising lead structures with a CN3 core, appropriate for potential future drug development. The compounds have the potential to be neurodegenerative therapeutic options, as well as: anti-inflammatory, anti-protozoal, anti-HIV, chemotherapeutic, anti-diabetic agents and so on. It is true that guanidine-based compounds of natural sources also, like synthetic and virtually designed drugs, have been of significant interest and have the potential to be useful therapeutic options in the future. As for now, however, there is not sufficient data to support their use in a number of the suggested areas, and further studies are required.

Preliminary investigation of anticancer activity by determining the DNA binding and antioxidant potency of new ferrocene incorporated N,N',N″-trisubstituted phenylguanidines.

Six new bioactive ferrocene based phenylguanidines were successively synthesized and characterized by means of various analytical techniques like elemental analysis, FT-IR, multinuclear ((1)H and (13)C) NMR, UV-Vis spectroscopy and cyclic voltammetry. The interaction of compounds with DNA was investigated by spectroscopic and cyclic voltammetric measurements. The interaction was found to be the electrostatic and the binding constants values were impressively larger. Compounds f-1, f-2, f-3 have slight larger binding constant values ranging from 0.8×10(5) to 2.4×10(5) as compared to g-1, g-2 and g-3 ranging from 7.6×10(4) to 1.1×10(5) which is most probably due to the presence of ferrocene at para position where the delocalization of electrons is maximum. Antioxidant activity was determined by UV-Vis spectrophotometer by using DPPH as a free radical. All the compounds exhibit good antioxidant activity and the results so obtained support the structure activity relationship.

Ferrocene-based guanidine derivatives: in vitro antimicrobial, DNA binding and docking supported urease inhibition studies.

Some novel ferrocenyl guanidines 1-8 were synthesized and characterized by different spectroscopic methods, elemental analysis and single crystal X-rays diffraction techniques. The crystallographic studies revealed that the existence of the strong non-bonding interactions facilitate these molecules to interact with biological macro-molecules like DNA that described to inherit good biological activities. The DNA interaction studies carried out by cyclic voltammetry (CV) and UV-visible spectroscopy are in close agreement with the binding constants (K) (0.79-5.4) × 10(5) (CV) and (0.72-5.1) × 10(5) (UV-vis). The shift in peak potential, current and absorption maxima of the studied ferrocenyl guanidines in the presence of DNA revealed that CV coupled with UV-vis spectroscopy could provide an opportune to characterize metal-based compounds-DNA interaction mechanism, a prerequisite for the design of new anticancer agents and understanding the molecular basis of their action. The compounds 1-8 have been screened for their antibacterial, antifungal and urease inhibition potency. A concurrent in silico study has also been applied on ferrocene moiety impregnated guanidines 1-8 to identify most active compounds having for inhibiting the activity of urease (pdb id 3LA4). Most of the compounds were found as potent inhibitors of urease and the compound 1 was found to be the most active with an IC50 of 16.83 ± 0.03 µM. The docking scores are in close agreement with the in vitro obtained IC50 values of inhibitors 1-8.

Crystallographic structure and quantum chemical computations of 1-(3,4-dimethylphenyl)-3-phenyl-5-(4-methoxyphenyl)-2-pyrazoline.

In this study the experimental crystallographic structure and the calculated optimized geometric parameters, vibrational wavenumbers, (1)H NMR and (13)C NMR chemical shift values, electronic absorption maximum wavelength values, HOMO-LUMO analysis, and molecular electrostatic potential (MEP) of 1-(3,4-dimethylphenyl)-3-phenyl-5-(4-methoxyphenyl)-2-pyrazoline (in abbreviated 1h), molecule, (C24H24N2O), by using density functional theory (DFT/B3LYP) method with 6-311++G(d,p) basis set in the ground state have been reported for the first time. Furthermore the IR and Raman spectra of title molecule were simulated by using calculated vibrational results. Geometric parameters (bond lengths and bond angles) vibrational wavenumbers and (13)C &(1)H NMR chemical shift values for the mentioned compound calculated at B3LYP/6-311++G(d,p) level are in good agreement with the experimental data.

Anti-leishmanial activity of heteroleptic organometallic Sb(v) compounds.

In seeking new drugs for the treatment of the parasitic disease Leishmaniasis, an extensive range of organometallic antimony(v) dicarboxylates of the form [SbR3(O2CR')2] have been synthesised, characterised and evaluated. The organometallic moieties (R) in the complexes vary in being Ph, tolyl (o, m or p), or benzyl. The carboxylates are predominantly substituted benzoates with some compounds incorporating acetato or cinnamato ligands. The crystal structures of [Sb(p-Tol)3(O2CC6H2-3,4,5-(OMe)3)2]·0.5PhMe and [SbPh3(m-CH3C6H4CH2CO2)2] were determined and shown to adopt a typical trigonal pyramidal geometry, being monomeric with a five coordinate Sb centre. In total, the biological activity of 26 Sb(v) compounds was assessed against the Leishmania major parasite, and also human fibroblast skin cells to give a measure of general toxicity. Of these, 11 compounds (predominantly substituted benzoates with m- or p-tolyl ligands) proved to be highly effective against the parasite amastigotes at concentrations of 0.5-3.5 µM, while being non-toxic towards the mammalian cells at levels below 25 µM, making them highly promising drug candidates.

Solution-phase microwave assisted parallel synthesis of N,N'-disubstituted thioureas derived from benzoic acid: biological evaluation and molecular docking studies.

An efficient and facile microwave-assisted solution phase parallel synthesis for a 26-member library of N,N'-disubstituted thiourea analogs were accomplished successfully. The reaction time for synthesis of analogs was drastically reduced from a reported 8-12 h to only 10 min. Compounds were more than 95% pure, as characterized by modern analytical techniques, i.e. (1)H &(13)C NMR and FT-IR. The solid phase structural analysis has also been performed by single crystal XRD analysis. Synthesized compounds were preliminary screened for their in vitro urease inhibition and antifungal activity. Most of the compounds were found to be potent inhibitors of urease. However, the most significant activity was found for 11 with IC50 of 1.67 µM. The docking scores correlate with the IC50 values of inhibitors.

Synthesis, structural characterization and in vitro biological screening of some homoleptic copper(II) complexes with substituted guanidines.

A series of homoleptic copper(II) complexes (1a-8a) with N,N',N″-trisubstituted guanidines, [Cu(II){PhCONHC(NHR)NPh}(2)] (where R = phenyl (1a), n-butyl (2a), sec-butyl (3a), cyclohexyl (4a), 1-naphthyl (5a), 2,4-dichlorophenyl (6a), 3,4-dichlorophenyl (7a), and 3,5-dichlorophenyl (8a)) have been synthesized and characterized by elemental analyses, FT-IR, UV-visible, (1)H and (13)C NMR spectroscopy, and single crystal X-ray diffraction analysis. The X-ray crystal structures revealed that the complexes 2a and 4a are mononuclear in the solid state and that the geometry around the copper atom is nearly square planar. In both the cases, N,N',N″-trisubstituted guanidine ligands have been coordinated to the Cu(II) through the oxygen and nitrogen atoms. The synthesized guanidines and their complexes were initially screened for their anti-microbial activities, and Brine Shrimps Lethality assay. The complexes were also screened for in vitro cytotoxicity activity in human cell lines carcinomas A498, EVSAT, H226, IGROV, M19, MCF-7 and WIDR. The results show a moderate level of cytotoxicity against these seven human cancer cell lines as compared with standard chemotherapeutic drugs.