Molecular structure, vibrational spectra and DFT molecular orbital calculations (TD-DFT and NMR) of the antiproliferative drug Methotrexate

IgG antibodies mediated gold nanoparticles conjugated to methotrexate as targeted chemotherapy for lung cancer

Vincamine, a natural chemical, was used as a reducing agent in the synthesis of IgG antibodies mediated biogenic gold nanoparticles (IgGAuNPs). Eventually, the synthesised IgGAuNPs were bioconjugated with the chemotherapeutic drug methotrexate (MTX-IgGAuNPs). The IgG isotype can target cancer cells through polymorphic Fc gamma receptors (FcγRs) and have therapeutic effects. They can restrict cell division by inhibiting different intracellular signal transduction pathways and activating NK cells and macrophages through antibody-dependent cellular cytotoxicity and macrophage-mediated antibody-dependent phagocytosis, respectively. Further, IgGAuNPs and MTX-IgGAuNPs were characterised by physical techniques. Moreover, 3D conformational changes in the structure of IgG were analysed by fluorescence spectroscopy during and after the synthesis of IgGAuNPs. Furthermore, the IgGAuNPs and MTX-IgGAuNPs were effective against lung cancer (A549 cells), while they were found to be non-toxic against normal cells (NRK cells). The effectiveness of IgGAuNPs and MTX-IgGAuNPs was examined by MTT cytotoxicity assay, DCFDA method for the production of ROS, and release of Cyt-c from the mitochondria for caspase-3-mediated apoptosis. Moreover, the confirmation of internalisation of particles into the nucleus was examined under the DAPI assay, and it was found that particles caused nuclear fragmentation, which was also an indication of apoptosis.

Hybrid Cyanine/Methotrexate Nanoparticles for Synergistic PDT/Chemotherapy of Breast Cancer

Typically, nanomedicine was prepared using a nanocarrier to load cargo for specific purposes. In this work, a carrier-free nanosystem for imaging and photodynamic (PDT)/chemo combination therapy was developed using simple self-assembly of a dye and a chemotherapeutic agent. The resulting nanoparticles (I₂-IR783/MTX@NPs) exhibited a spherical morphology with a size of 240.6 ± 2.5 nm. I₂-IR783/MTX@NPs had substantial internalization in 4T1 murine breast cancer cells and showed a synergistic anticancer effect after NIR light irradiation. Additionally, the 3D tumor model exhibits the same phototoxicity of nanoparticles as a 2D cell culture. The PDT efficiency of the nanosystem in the physiological environment was confirmed by the detection of intracellular reactive oxygen species as well as the live/dead viability/cytotoxicity assay following NIR light exposure. In addition, optical coherence tomography (OCT) was used as an alternative tool to monitor the response after treatment. Therefore, I₂-IR783/MTX@NPs show great potential use in theranostic application for breast cancer PDT-chemotherapy.

Synthesis, spectral characterization, and theoretical investigation of the photovoltaic properties of (E)-6-(4-(dimethylamino)phenyl)diazenyl)-2-octyl-benzoisoquinoline-1, 3-dione

This research work focuses on the synthesis, characterization through spectra (FT-IR, UV-vis, and ¹H-NMR) investigations, and the use of density functional theory (DFT) along with time-dependent density functional theory (TD-DFT) to investigate the electronic, structural, reactivity, photophysical properties, and the photovoltaic properties of a novel (E)-6-(4-(dimethylamino)phenyl)diazenyl)-2-octyl-benzoisoquinoline-1,3-dione. The structure of the synthesized compound was modeled using the Gaussian09W and GaussView6.0.16 softwares employing B3LYP and 6-31 + G(d) basis set. The DFT studies was performed in order to investigate the Frontier Molecular Orbital (FMO), Natural Bond Orbital (NBO), charge distribution, Nonlinear Optics (NLO), and stability of the titled molecule. The HOMO-LUMO energy gap which corresponds to the difference between HOMO and LUMO energies of the studied compound was found to be 2.806 eV indicating stiff and smooth nature of the titled molecule. This accounts for the less stability and high chemical reactivity of the compound. The photovoltaic properties were conducted to evaluate the light harvesting efficiency (LHE), short circuit current density (J_SC), Gibbs free energy of injection ([Formula: see text]), open cycled voltage (V_OC) and Gibbs free energy regeneration ([Formula: see text]) and solar cell conversion efficiency. Interestingly, the results obtained were found to be in good agreement with other experimental and computational findings.

Porous Silicon-Based Nanomedicine for Simultaneous Management of Joint Inflammation and Bone Erosion in Rheumatoid Arthritis

The lack of drugs that target both disease progression and tissue preservation makes it difficult to effectively manage rheumatoid arthritis (RA). Here, we report a porous silicon-based nanomedicine that efficiently delivers an antirheumatic drug to inflamed synovium while degrading into bone-remodeling products. Methotrexate (MTX) is loaded into the porous silicon nanoparticles using a calcium silicate based condenser chemistry. The calcium silicate-porous silicon nanoparticle constructs (pCaSiNPs) degrade and release the drug preferentially in an inflammatory environment. The biodegradation products of the pCaSiNP drug carrier are orthosilicic acid and calcium ions, which exhibit immunomodulatory and antiresorptive effects. In a mouse model of collagen-induced arthritis, systemically administered MTX-loaded pCaSiNPs accumulate in the inflamed joints and ameliorate the progression of RA at both early and established stages of the disease. The disease state readouts show that the combination is more effective than the monotherapies.

Methotrexate Detection in Serum at Clinically Relevant Levels with Electrochemically Assisted SERS on a Benchtop, Custom Built Raman Spectrometer

Therapeutic drug monitoring (TDM) is an essential clinical practice for optimizing drug dosing, thereby preventing adverse effects of drugs with a narrow therapeutic window, slow clearance, or high interperson pharmacokinetic variability. Monitoring methotrexate (MTX) during high-dose MTX (HD-MTX) therapy is necessary to avoid potentially fatal side effects caused by delayed elimination. Despite the efficacy of HD-MTX treatment, its clinical application in resource-limited settings is constrained due to the relatively high cost and time of analysis with conventional analysis methods. In this work, we developed (i) an electrochemically assisted surface-enhanced Raman spectroscopy (SERS) method for detecting MTX in human serum at a clinically relevant concentration range and (ii) a benchtop, Raman detection system with an integrated potentiostat, software, and data analysis unit that enables mapping of small areas of SERS substrates and quantitative SERS-based analysis. In the assay, by promoting electrostatic attraction between gold-coated nanopillar SERS substrates and MTX molecules in aqueous samples, a detection limit of 0.13 μM with a linear range of 0.43-2 μM was achieved in PBS. The implemented sample cleanup through gel filtration proved to be highly effective, resulting in a similar detection limit (0.55 μM) and linear range (1.81-5 μM) for both PBS and serum. The developed and optimized assay could also be used on the in-house built, Raman device. We showed that MTX detection can be carried out in less than 30 min with the Raman device, paving the way toward the TDM of MTX at the point-of-need and in resource-limited environments.

Experimental and theoretical studies of the influence of alkyl groups on the photovoltaic properties of (E)-6-((2, 3-dihydroxylnaphthalene)diazenyl)-1H-benzoisoquinoline-1,3-dione-based organic solar cell

The manipulation of the active dye material for application in dye-sensitized solar cell (DSSC) using simple or bulky group substituents is necessary for improved dye performance. Herein, we carried out a combined experimental and theoretical studies of different alkylated novel reactive (E)-6-(2,3-dihydroxyl naphthalene diazinyl)-1H-benzoisoquinoline-1,3-dione azo-based dyes using spectral (FTIR, UV-visible, and NMR) analysis and electronic structure theory method based first principle density functional theory (DFT) calculations to investigate the molecular electronic properties, structural analysis, excitation behavior, and the theoretical potential application in photovoltaic cell. The synthesized azo dye (azoD) was theoretically modeled by varying the number of alkyl chains denoted as AzoD₁, AzoD₂, AzoD₃, and AzoD₄ to represent azo dyes having ten (10), twelve (12), fourteen (14), and sixteen (16) alkyl chain length respectively. From the natural bond orbital (NBO) analysis, the higher stabilization energies, 227.80 and 227.77 kcal/mol respectively, recorded for AzoD₁ and AzoD₄ may be due to extra orbital contribution by π*(N₂₁-N₂₂) to π*C₅₄-C₅₆ 31.19 eV for AzoD₁ and π*(N₂₁-N₂₂) → π*(C₅₃-C₅₅) 31.43 eV AzoD₄ confirming that chain length affected the orbital interaction of the molecules. The driving force (ΔG_inject) of electron injection into the TiO₂ surface (- 1.92 to - 1.93) shown in this study is indicative that alkylated azo dyes are good for improved DSSCs performance. Again, the open circuit voltage (V_oc) of 1.090 (AzoD₁), 1.092 (AzoD₂), 1.093 (AzoD₃), and 1.095 (AzoD₄) are also evidence of the suitability of azo dyes as photosensitizers. All the spectroscopic analysis, FTIR, UV-visible, and NMR combined with theoretical calculations, provided accurate data for characterizing the titled azo dye compound and showed that it has good photophysical properties. The presence of alkyl groups and chain length promoted the stability of the dyes thereby making them suitable for application in DSSCs. Increase in chain length as well enhanced the electron injection into the conduction band of the semiconductor.

Prodrug based on halloysite delivery systems to improve the antitumor ability of methotrexate in leukemia cell lines

The prodrug approach, as well as the development of specific systems able to deliver a chemotherapeutic agent in the target site, decreasing the side effects often associated with its administration, are still a challenging. In this context, both methotrexate drug molecules (MTX) and biotin ligand moieties, whose receptors are overexpressed on the surface of several cancer cells, were loaded on halloysite nanotubes (HNTs) to develop nanomaterial based on multifunctional and "smart" delivery systems. To highlight the crucial role played by biotin, carrier systems based on HNTs and MTX were also synthetized. In detail, several approaches were envisaged: i) a supramolecular interaction between the clay and the drug; ii) a covalent grafting of the drug onto the HNTs external surface and, iii) a combination of both approaches. The nanomaterials obtained were characterized by thermogravimetric analysis, FT-IR, and UV-vis spectroscopies, DLS and ζ-potential measurements and the morphologies were imaged by HAADF/STEM investigations. Kinetic release experiments at different pH conditions were also performed. Finally, as a proof-of-concept application of our pro-drug delivery systems based on HNTs in cancer therapy, the cytotoxic effects were evaluated on acute myeloid leukemia cell lines, HL60 and its multidrug resistance variant, HL60R. The obtained results showed that both the MTX prodrug system and the biotinylated ones played a crucial role in the biological activity and, they are promising agents for the cancer treatments.

Quantification of Methotrexate in Human Serum Using Surface-Enhanced Raman Scattering-Toward Therapeutic Drug Monitoring

Therapeutic drug monitoring (TDM) can improve clinical care when using drugs with pharmacokinetic variability and a narrow therapeutic window. Rapid, reliable, and easy-to-use detection methods are required in order to decrease the time of analysis and can also enable TDM in resource-limited settings or even at bedside. Monitoring methotrexate (MTX), an anticancer drug, is critical since it is needed to follow the drug clearance rate and decide how to administer the rescue drug, leucovorin (LV), in order to avoid toxicity and even death. We show that with the optimized nanopillar-assisted separation (NPAS) method using surface-enhanced Raman scattering, we were able to measure MTX in PBS and serum in the linear range of 5-150 μM and confirmed that MTX detection can be carried out even in the presence of LV. Additionally, when NPAS was combined with centrifugal filtration, a quantification limit of 2.1 μM for MTX in human serum sample was achieved. The developed detection method enables fast detection (10 min) and quantification of MTX from human serum (>90% accuracy). Furthermore, we show the potential of the developed method for TDM, when quantifying MTX from clinical samples, collected from patients who are undergoing high-dose MTX therapy.

In situ Analytical Quality Control of chemotherapeutic solutions in infusion bags by Raman spectroscopy

Analytical Quality Control (AQC) in centralised preparation units of oncology centers is a common procedure relying on the identification and quantification of the prepared chemotherapeutic solutions for safe intravenous administration to patients. Although the use of Raman spectroscopy for AQC has gained much interest, in most applications it remains coupled to a flow injection analyser (FIA) requiring withdrawal of the solution for analysis. In addition to current needs for more rapid and cost-effective analysis, the risk of exposure of clinical staff to the toxic molecules during daily handling is a serious concern to address. Raman spectroscopic analysis, for instance by Confocal Raman Microscopy (CRM), could enable direct analysis (non-invasive) for AQC directly in infusion bags. In this study, 3 anticancer drugs, methotrexate (MTX), 5-fluorouracil (5-FU) and gemcitabine (GEM) have been selected to highlight the potential of CRM for withdrawal free analysis. Solutions corresponding to the clinical range of each drug were prepared in 5% glucose and data was collected from infusion bags placed under the Raman microscope. Firstly, 100% discrimination has been obtained by Partial Least Squares Discriminant Analysis (PLS-DA) confirming that the identification of drugs can be performed. Secondly, using Partial Least Squares Regression (PLSR), quantitative analysis was performed with mean % error of predicted concentrations of respectively 3.31%, 5.54% and 8.60% for MTX, 5-FU and GEM. These results are in accordance with the 15% acceptance criteria used for the current clinical standard technique, FIA, and the Limits of Detection for all drugs were determined to be substantially lower than the administered range, thus highlighting the potential of confocal Raman spectroscopy for direct analysis of chemotherapeutic solutions.

Methotrexate Gold Nanocarriers: Loading and Release Study: Its Activity in Colon and Lung Cancer Cells

In the present study, the synthesis of gold nanoparticles (AuNPs) loaded with methotrexate (MTX) has been carried out in order to obtain controlled size and monodispersed nanocarriers of around 20 nm. The characterization study shows metallic AuNPs with MTX polydispersed on the surface. MTX is linked by the replacement of citrate by the MTX carboxyl group. The drug release profiles show faster MTX release when it is conjugated, which leads to the best control of plasma concentration. Moreover, the enhanced release observed at pH 5 could take advantage of the pH gradients that exist in tumor microenvironments to achieve high local drug concentrations. AuNP–MTX conjugates were tested by flow cytometry against lung (A-549) and colon (HTC-116) cancer cell lines. Results for A-549 showed a weaker dose–response effect than for colon cancer ones. This could be related to the presence of folate receptors in line HTC-116 in comparison to line A-549, supporting the specific uptake of folate-conjugated AuNP–MTX by folate receptor positive tumor cells. Conjugates exhibited considerably higher cytotoxic effects compared with the effects of equal doses of free MTX. Annexin V-PI tests sustained the cell death mechanism of apoptosis, which is normally disabled in cancer cells.

Ultrasensitive SERS detection of antitumor drug methotrexate based on modified Ag substrate

Methotrexate (MTX) is a drug with broad-spectrum antitumor activity that is of great importance in therapeutic drug monitoring applications. In this essay, the two-step modified concentrated Ag colloid with the assistance of KF and MgSO₄ was used as the SERS active substrate for the ultrasensitive detection of MTX and its commercial formulations (tablets). It can be found that the two-step modification of the samples is a crucial procedure to remove the by-products in the synthesis of Ag colloid and further concentrate the Ag colloid. Under the optimal detection conditions, the minimum detection concentration of MTX is 1 × 10^-16 mol/L. And, there is a good linear relationship over a wide concentration range of 1 × 10^-16-1 × 10^-6 mol/L. The labelled amounts of the two manufacturers of MTX commercial tablets are in the range of 96.4-104.3% with the RSDs between 1.8% and 3.5% by this method, which are in accordance with the methodological requirements. These results prove that the proposed SERS method exhibits a good reproducibility and ultra-high sensitivity for the detection of the antitumor drug MTX.

Synthesis of controlled-size silver nanoparticles for the administration of methotrexate drug and its activity in colon and lung cancer cells

A controlled synthesis of methotrexate (MTX) silver nanoparticles (AgNPs-MTX) using borohydride and citrate as reduction and reduction/capping agents, respectively, was performed in order to obtain AgNPs-MTX conjugates with a narrow size distribution. Their characterization showed polydispersed spherical shape nanoparticles with a mean size around 13 nm and distribution range between 7–21 nm. The presence of MTX was confirmed by FTIR and EDX analysis. Spectroscopic determinations suggest the chemisorption of MTX through a carboxylic group (–COOH) onto AgNPs via the exchange with a citrate molecule. Drug loading capacities calculated for AgNPs synthesized using different amounts of MTX were 28, 31 and 40%. In vitro drug release tests depicted similar release profiles for all conjugated amounts releasing between 77 to 85% of the initial MTX loaded into the AgNPs. With respect to free MTX, the addition of the nanocarrier delayed its release and also changed its pharmacokinetics. Free MTX is released after 3 hours following a first order kinetic model, whereas in the presence of AgNPs, a fast initial release is observed during the first 5 hours, followed by a plateau after 24 hours. In this case, AgNPs-MTX fitted a Higuchi model, where its solubilization is controlled by a diffusion process. Results obtained from flow cytometry of different cell lines treated with AgNPs-MTX demonstrated the combined anticancer effect of both reagents, decreasing the percentage of living cells in a colon cancer cell line (HTC-116) down to 40% after 48 hours of exposure. This effect was weaker but still significant for a lung cancer cell line (A-549). Finally, a zebrafish assay with AgNPs-MTX did not show any significant cytotoxic effect, confirming thereby the reduction of systemic drug toxicity achieved by coupling MTX to AgNPs. This observed toxicity reduction in the zebrafish model implies also a probable improvement of the usage of AgNPs-MTX in chemotherapy against human cancers.

A controlled synthesis of methotrexate (MTX) silver nanoparticles (AgNPs-MTX) using borohydride and citrate as reduction and reduction/capping agents, respectively, was performed in order to obtain AgNPs-MTX conjugates with a narrow size distribution.

Structural characterization and hypolipidemic activities of purified stigma maydis polysaccharides

This study aimed to investigate structural features and antihyperlipidemic effects of the stigma maydis polysaccharide, termed SMP-1. This polysaccharide was composed of D-mannose, L-rhamnose, D-glucose, D-galactose, L-arabinose, D-xylose, and D-galacturonic acid, with a molar ratio of 1.00:0.21:1.41:1.44:0.70:0.44:0.56. The SMP-1 was mainly bonded by (1 → 6) and (1 → 3) linkages, with various monosaccharides being evenly distributed in the main and side chains. Moreover, SMP-1 had neither triple-helical structure nor molecular aggregation. Importantly, the SMP-1 could effectively bind the bile acids in vitro and significantly lower the total cholesterol, triglyceride, low-density lipoprotein cholesterol levels, and moderately increase the high-density lipoprotein cholesterol level in poloxamer 407-induced hyperlipidemic mice. Moreover, pretreatment with SMP-1 (≥300 mg/kg) could remarkably reduce fat accumulation and restore hepatocyte morphology in the liver of hyperlipidemic mice. Altogether, these findings indicated that SMP-1 could be developed as a safe and effective food supplement for preventing and treating hyperlipidemic disorders.

DNA Facilitates the Sorption of Polycyclic Aromatic Hydrocarbons on Montmorillonites

The sorption of polycyclic aromatic hydrocarbons (PAHs) to montmorillonites is largely influenced by their interactions with dissolved organic matter (DOM). However, the role of DOM rather than humic and fulvic acids (e.g., extracellular DNA) in the PAH sorption to soil clays is little known. Here, we demonstrate that extracellular double-stranded salmon testes DNA substantially increased the sorption of phenanthrene and pyrene to Na-, Ca-, and Fe-modified montmorillonites. All PAH sorption isotherms fitted the linear and Freundlich models reasonably well ( R² = 0.918-0.999). Distribution coefficients were increased from 0.0458-0.103 and 0.0493-0.141 L/g at 0 mg/L DNA to 0.413-0.589 and 0.385-0.560 L/g at 10 mg/L DNA for phenanthrene and pyrene, respectively. Spectroscopic and computational chemistry analyses confirmed that PAHs were first inserted into DNA by binding with the nucleobases via van der Waals and π-π electron donor-acceptor interactions. Compared to PAHs, the DNA-PAH complex can be more easily sorbed to cation-modified montmorillonites by complexation between DNA phosphate and exchangeable cations in addition to intercalation into clay interlayers. This work highlights the importance of understanding the control on contaminant sorption by many organic compounds that are ubiquitous in soils but not represented by humic and fulvic acids.

Induction of Au-methotrexate conjugates by sugar molecules: production, assembly mechanism, and bioassay studies

Au-methotrexate (Au-MTX) conjugates induced by sugar molecules were produced by a simple, one-pot, hydrothermal growth method. Herein, the Au(III)-MTX complexes were used as the precursors to form Au-MTX conjugates. Addition of different types of sugar molecules with abundant hydroxyl groups resulted in the formation of Au-MTX conjugates featuring distinct characteristics that could be explained by the diverse capping mechanisms of sugar molecules. That is, the instant-capping mechanism of glucose favored the generation of peanut-like Au-MTX conjugates with high colloidal stability while the post-capping mechanism of dextran and sucrose resulted in the production of Au-MTX conjugates featuring excellent near-infrared (NIR) optical properties with a long-wavelength plasmon resonance near 630-760 nm. Moreover, in vitro bioassays showed that cancer cell viabilities upon incubation with free MTX, Au-MTX conjugates doped with glucose, dextran and sucrose for 48 h were 74.6%, 55.0%, 62.0%, and 63.1%, respectively. Glucose-doped Au-MTX conjugates exhibited a higher anticancer activity than those doped with dextran and sucrose, therefore potentially presenting a promising treatment platform for anticancer therapy. Based on the present study, this work may provide the first example of using biocompatible sugars as regulating agents to effectively guide the shape and assembly behavior of Au-MTX conjugates. Potentially, the synergistic strategy of drug molecules and sugar molecules may offer the possibility to create more gold-based nanocarriers with new shapes and beneficial features for advanced anticancer therapy.

Novel morphologies of poly(allyamine hydrochloride)-methotrexate nanoassemblies for methotrexate delivery

Poly(allylamine hydrochloride)-methotrexate (PAH-MTX) nanoassemblies with novel morphologies (i.e. nanostrips, nanorolls, nanosheets, and nanospheres) were achieved for the first time via supramolecular self-assembly directed by the synergistic action of various non-covalent interactions between PAH and MTX molecules in aqueous solution. Herein, MTX acted in a versatile manner as both a morphology-regulating agent and a small molecular hydrophobic anticancer drug. Moreover, different morphologies presented diverse drug release profiles, which may be caused by the distinctive interactions between PAH and MTX molecules. Synergistically non-covalent interactions, including electrostatic interactions, van der Waals forces, and hydrogen bonding, favored easier matrix corrosion and more rapid drug release of non-spherical structures (i.e. nanostrips, nanorolls, and nanosheets) through the ligand exchange process. On the other hand, the highly sealed encapsulation mode for hydrophobic MTX molecules made the nanospheres exhibit slower and better controlled release. In addition, in vitro bioassay tests showed that nanostrips displayed the most obvious suppression on the viability of cancer cells among other morphologies, especially after a longer duration. The strategy of using small molecular anticancer drugs not as passively delivered cargoes but as effective molecular building blocks, opens up a new way to develop self-delivering drugs for anticancer therapy.

Enhanced antitumor efficacy of poly(D,L-lactide-co-glycolide)-based methotrexate-loaded implants on sarcoma 180 tumor-bearing mice

Purpose

Methotrexate is widely used in chemotherapy for a variety of malignancies. However, severe toxicity, poor pharmacokinetics, and narrow safety margin of methotrexate limit its clinical application. The aim of this study was to develop sustained-release methotrexate-loaded implants and evaluate antitumor activity of the implants after intratumoral implantation.

Materials and methods

We prepared the implants containing methotrexate, poly(D,L-lactide-co-glycolide), and polyethylene glycol 4000 with the melt-molding technique. The implants were characterized with regards to drug content, morphology, in vitro, and in vivo release profiles. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were carried out to investigate the physicochemical properties of the implants. Furthermore, the antitumor activity of the implants was tested in a sarcoma 180 mouse model.

Results

The implants were prepared as solid rods. Scanning electron microscopy images showed a smooth surface of the implant, suggesting that methotrexate was homogeneously dispersed in the polymeric matrix. The results of DSC and FTIR indicated that no significant interaction between methotrexate and the polymer was observed in the implants. Both in vitro and in vivo release profiles of the implants were characterized by burst release followed by sustained release of methotrexate. Intratumoral implantation of methotrexate-loaded implants could efficiently delay tumor growth. Moreover, an increase in the dose of implants led to a higher tumor suppression rate without additional systemic toxicity.

Conclusion

These results demonstrate that methotrexate-loaded implants had significant antitumor efficacy in a sarcoma 180 mouse model without dose-limiting side effects, and suggest that the implants could be potentially applied as an intratumoral delivery system to treat cancer.

A DFT investigation of structure, spectroscopic properties and tautomerism of the anticonvulsant drug Lyrica

The Lyrica (Pregabalin) is a novel anticonvulsant and neuropathic pain drug, which could exist as four possible conformers. Herein, employing density functional theory (DFT), and handling the solvent effects with the PCM model, the structural parameters, energetic behavior, natural bond orbital analysis (NBO), as well as tautomerism mechanization of the Lyrica are investigated. The L1 (-OH form) is the most stable conformer of the Lyrica, which can be tautomerized to the L5 (-NH form) tautomer. The tautomerism reaction includes an intramolecular-proton transfer, which affects considerably the structural parameters and atomic charges of the L1. The DFT-computed NMR chemical shifts and IR vibrational frequencies are good in agreement with the experimental values, confirming suitability of the optimized geometry for the Lyrica.

Density functional theory (DFT) and natural bond orbital (NBO) study of vibrational spectra and intramolecular hydrogen bond interaction of L-ornithine-L-aspartate

In this study, exhaustive conformations of (S)-4-amino-4-carboxybutan-1-aminium (S)-3-amino-3-carboxypropanoate (LOLA) have been scanned. Experimental and theoretical studies on the structure and vibrations of the title compound are presented. The optimized molecular structure, vibrational wavenumbers, Mulliken atomic charges, natural bond orbital (NBO) and molecular electrostatic potential studies have been performed by density functional theory (DFT) using B3LYP method with the 6-311++G(d,p) basis set. Computed X-ray powder diffraction (XRPD) data has been carried out by DFT calculations and ab initio from measured XRPD finding. The LOLA molecular geometry has been determined which exists in the form of salt by intramolecular H-bonds and ionic bonding. Moreover, calculated vibrational frequencies were applied to simulate IR and Raman spectra of the title compound which showed excellent agreement with observed spectra. Reliable vibrational assignments have been made on the basis of potential energy distribution (PED) and 0.992 has been obtained by least squares method which is the uniform scaled factor for theoretical frequencies at 6-311++G(d,p) basis set. In addition, the hydrogen bonding in LOLA molecule has been explored by calculation of the hyperconjugative charge transfer interaction on [LP X-σ(*)(Y-H)], under NBO analysis, Mulliken atomic charge analysis, molecular electrostatic potential map (MEP) and vibrational spectra. Finally, HOMO-LUMO of the title compound has been plotted for predicting reactive sites.

Molecular structure (monomeric and dimeric) and hydrogen bonds in 5-benzyl 2-thiohydantoin studied by FT-IR and FT-Raman spectroscopy and DFT calculations

In the present work the structural and spectral characteristics of 5-benzyl-2-thiohydantoin (5-BTH) have been studied by methods of infrared, Raman spectroscopy and quantum chemistry. Electrostatic potential surface, optimized geometry, harmonic vibrational frequencies, infrared intensities and activities of Raman scattering were calculated by density functional theory (DFT) employing B3LYP with complete relaxation in the potential energy surface using 6-311G++(d,p) basis set. Our results support the hydrogen bonding pattern proposed by reported crystalline structure. Stability of the molecule arising from hyperconjugative interactions, charge delocalization have been analyzed using natural bond orbital (NBO) analysis. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. UV-vis spectrum of the compound was recorded in methanol solvent. The TD-DFT calculations have been performed to explore the influence of electronic absorption spectra in the gas phase, as well as in solution environment using PCM and 6-311++G(d,p) basis set. In addition, the thermodynamic properties of the compound were calculated at different temperatures and corresponding relations between the properties and temperature were also studied.

Study on molecular structure, spectroscopic investigation (IR, Raman and NMR), vibrational assignments and HOMO-LUMO analysis of L-sodium folinate using DFT: a combined experimental and quantum chemical approach

In the present work, an exhaustive conformational search of N-[4-[[(2-amino-5-formyl-(6S)-3,4,5,6,7,8-hexahydro-4-oxo-6-pteridinyl)methyl]amino]benzoyl]-L-glutamic acid disodium salt (L-SF) has been preformed. The optimized structure of the molecule, vibrational frequencies and NMR spectra studies have been calculated by density functional theory (DFT) using B3LYP method with the 6-311++G (d, p) basis set. IR and FT-Raman spectra for L-SF have been recorded in the region of 400-4000 cm(-1) and 100-3500 cm(-1), respectively. 13C and 1H NMR spectra were recorded and 13C and 1H nuclear magnetic resonance chemical shifts of the molecule were calculated based on the gauge-independent atomic orbital (GIAO) method. Finally all of the calculation results were applied to simulate IR, Raman, 1H NMR and 13C NMR spectrum of the title compound which showed excellent agreement with observed spectrum. Furthermore, reliable vibrational assignments which have been made on the basis of potential energy distribution (PED) and characteristic vibratinonal absorption bands of the title compound in IR and Raman have been figured out. HOMO-LUMO energy and Mulliken atomic charges have been evaluated, either.

Quantum mechanical, spectroscopic studies (FT-IR, FT-Raman, NMR, UV) and normal coordinates analysis on 3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide

Famotidine (3-([2-(diaminomethyleneamino) thiazol-4-yl] methylthio)-N'-sulfamoylpropanimidamide) is a histamine H2-receptor antagonist that inhibits stomach acid production, and it is commonly used in the treatment of peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD/GORD). Quantum chemical calculations of the equilibrium geometry of famotidine in the ground state were carried out using density functional theory (DFT/B3LYP) with the 6-311G(d,p) basis set. In addition, harmonic vibrational frequencies, infrared intensities and Raman activities were calculated at the same level of theory. A detailed interpretation of the infrared and Raman spectrum of the drug is also reported. Theoretical simulations of the FT-IR, and FT-Raman spectra of the title compound have been calculated. Good correlations between the experimental (1)H and (13)C NMR chemical shifts and calculated GIAO shielding tensors were found. The results of the energy and oscillator strength calculations by time-dependent density functional theory (TD-DFT) supplement the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis were presented. The dipole moment, linear polarizability and first order hyperpolarizability values were also computed. The linear polarizability and first order hyperpolarizabilities of the studied molecule indicate that the compound is a good candidate for nonlinear optical materials.

Molecular structure and vibrational spectra of Irinotecan: a density functional theoretical study

The solid phase FTIR and FT-Raman spectra of Irinotecan have been recorded in the regions 400-4000 and 50-4000 cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The structure of the molecule was optimized and the structural characteristics were determined by density functional theory (DFT) using B3LYP method with 6-31G(d) as basis set. The vibrational frequencies were calculated for Irinotecan by DFT method and were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. The infrared spectrum was also simulated from the calculated intensities. Besides, molecular electrostatic potential (MEP), frontier molecular orbitals (FMO) analysis were investigated using theoretical calculations.

Reaction mechanism and chemoselectivity of intermolecular cycloaddition reactions between phenyl-substituted cyclopropenone ketal and methyl vinyl ketone

In this paper, the mechanisms of the intermolecular [3+2] and [1+2] cycloaddition reactions of 1,1/1,3-dipolar π-delocalized singlet vinylcarbenes, which is obtained from cyclopropenone, with an electron-deficient C═O or C═C dipolarophile, to generate five-membered ring products are first disclosed by the density functional theory (DFT). Four reaction pathways, including two concerted [3+2] cycloaddition reaction pathways and two stepwise reaction pathways (an initial [1+2] cycloaddition and then a rearrangement from the [1+2] cycloadducts to the final [3+2] cycloadducts), are investigated at the B3LYP/6-31G(d,p) level of theory. The calculated results reveal that, in contrast to the concerted C═O [3+2] cycloaddition reaction pathway, which is 7.1 kcal/mol more energetically preferred compared with its stepwise reaction pathway, the C═C dipolarophile favors undergoing [1+2] cycloaddition rather than concerted [3+2] cycloaddition (difference of 5.3 kcal/mol). The lowest free energy barrier of the C═O concerted [3+2] cycloaddition reaction pathway shows that it predominates all other reaction pathways. This observation is consistent with the finding that the C═O [3 + 2] cycloadduct is the main product under experimental conditions. In addition, natural bond orbital second-order perturbation charge analyses are carried out to explain the preferred chemoselectivity of C═O to the C═C dipolarophile and the origins of cis-stereoselectivity for C═C [1+2] cycloaddition. Solvent effects are further considered at the B3LYP/6-31G(d,p) level in the solvents CH(3)CN, DMF, THF, CH(2)Cl(2), toluene, and benzene using the PCM model. The results indicate that the relative reaction trends and the main products are insensitive to the polarity of the reaction solvent.