Vibrational spectral analysis of anti-neurodegenerative drug Levodopa: A DFT study

Tricompartmental Microcarriers with Controlled Release for Efficient Management of Parkinson's Disease

Parkinson's is a progressive neurodegenerative disease of the nervous system. It has no cure, but its symptoms can be managed by supplying dopamine artificially to the brain.This work aims to engineer tricompartmental polymeric microcarriers by electrohydrodynamic cojetting technique to encapsulate three PD (Parkinson's disease) drugs incorporated with high encapsulation efficiency (∼100%) in a single carrier at a fixed drug ratio of 4:1:8 (Levodopa (LD): Carbidopa(CD): Entacapone (ENT)). Upon oral administration, the drug ratio needs to be maintained during subsequent release from microparticles to enhance the bioavailability of primary drug LD. This presents a notable challenge, as the three drugs vary in their aqueous solubility (LD > CD > ENT). The equilibrium of therapeutic release was achieved using a combination of FDA-approved polymers (PLA, PLGA, PCL, and PEG) and the disc shape of particles. In vitro studies demonstrated the simultaneous release of all the three therapeutics in a sustained and controlled manner. Additionally, pharmacodynamics and pharmacokinetics studies in Parkinson's disease rats induced by rotenone showed a remarkable improvement in PD conditions for the microparticles-fed rats, thereby showing a great promise toward efficient management of PD.

Quantum-level machine learning calculations of Levodopa

Many drug molecules contain functional groups, resulting in a torsional barrier corresponding to rotation around the bond linking the fragments. In medicinal chemistry and pharmaceutical sciences, inclusive of drug design studies, the exact calculation of the potential energy surface (PES) of these molecular torsions is extremely important and precious. Machine learning (ML), including deep learning (DL), is currently one of the most rapidly evolving tools in computer-aided drug discovery and molecular simulations. In this work, we used ANI-1x neural network potential as a quantum-level ML to predict the PESs of the L-3,4-dihydroxyphenylalanine (Levodopa) antiparkinsonian drug molecule. The electronic energies and structural parameters calculated by density functional theory (DFT) using the wB97X method and all possible Pople's basis sets indicated the 6-31G(d) basis set, when used with the wB97X functional, exhibits behavior similar to that of the ANI-1x model. The vibrational frequencies investigation showed a linear correlation between DFT and ML data. All ANI-1x calculations were completed quickly in a very short computing time. From this perspective, we expect the ANI-1x dataset applied in this work to be appreciably efficient and effective in computational structure-based drug design studies.

Probing solution conformations of l-DOPA: Integration of experiment and simulation via vibrational optical activity

l-DOPA plays a critical role as a precursor to dopamine and is a standard treatment for Parkinson's disease. Recent research has highlighted the potential therapeutic advantages of deuterated l-DOPA analogs having a longer biological half-life. For their spectroscopic characterization, the in-detail characterization of l-DOPA itself is necessary. This article presents a thorough examination of the vibrational spectra of l-DOPA, with a particular emphasis on chirally sensitive VOA techniques. We successfully obtained high-quality Raman and ROA spectra of l-DOPA in its cationic form, under low pH conditions, and at a high concentration of 100 mg/ml. These spectra cover a broad spectral range, allowing for precise comparisons with theoretical simulations. We also obtained IR and VCD spectra, but they faced limitations due to the narrow accessible spectral region. Exploration of l-DOPA's conformational landscape revealed its intrinsic flexibility, with multiple coexisting conformations. To characterize these conformations, we employed two methods: one involved potential energy surface scans with implicit solvation, and the other utilized molecular dynamics simulations with explicit solvation. Comparing ROA spectra from different conformer groups and applying spectral decomposition proved crucial in determining the correct conformer ratios. The use of explicit solvation significantly improved the quality of the final simulated spectral profiles. The accurate determination of conformer ratios, rather than solely relying on the number of averaged spectra, played a crucial role in simulation accuracy. In conclusion, our study offers valuable insights into the structure and conformational behavior of l-DOPA and represents a valuable resource for subsequent spectroscopic studies of its deuterated analogs.

Improvement of the cardiovascular effect of methyldopa by complexation with Zn(II): Synthesis, characterization and mechanism of action

BACKGROUND

the antihypertensive drug α-methyldopa (MD) stands as one of the extensively used medications for managing hypertension during pregnancy. Zinc deprivation has been associated with many diseases. In this context, the synthesis of a Zn coordination complex [Zn(MD)(OH)(H2O)2]·H2O (ZnMD) provide a promising alternative pathway to improve the biological properties of MD.

METHODS

ZnMD was synthesized and physicochemically characterized. Fluorescence spectral studies were conducted to examine the binding of both, the ligand and the metal with bovine serum albumin (BSA). MD, ZnMD, and ZnCl2 were administered to spontaneous hypertensive rats (SHR) rats during 8 weeks and blood pressure and echocardiographic parameters were determined. Ex vivo assays were conducted to evaluate levels of reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARS), and nitric oxide (NO). Cross-sectional area (CSA) and collagen levels of left ventricular cardiomyocytes were also assessed. Furthermore, the expression of NAD(P)H oxidase subunits (gp91phox and p47phox) and Superoxide Dismutase 1 (SOD1) was quantified through western blot analysis.

RESULTS

The complex exhibited a moderate affinity for binding with BSA showing a spontaneous interaction (indicated by negative ΔG values) and moderate affinity (determined by affinity constant values). The binding process involved the formation of Van der Waals forces and hydrogen bonds. Upon treatment with MD and ZnMD, a reduction in the systolic blood pressure in SHR was observed, being ZnMD more effective than MD (122 ± 8.1 mmHg and 145 ± 5.6 mmHg, at 8th week of treatment, respectively). The ZnMD treatment prevented myocardial hypertrophy, improved the heart function and reduced the cardiac fibrosis, as evidenced by parameters such as left ventricular mass, fractional shortening, and histological studies. In contrast, MD did not show noticeable differences in these parameters. ZnMD regulates negatively the oxidative damage by reducing levels of ROS and lipid peroxidation, as well as the cardiac NAD(P)H oxidase, and increasing SOD1 expression, while MD did not show significant effect. Moreover, cardiac nitric oxide levels were greater in the ZnMD therapy compared to MD treatment.

CONCLUSION

Both MD and ZnMD have the potential to be transported by albumin. Our findings provide important evidence suggesting that this complex could be a potential therapeutic drug for the treatment of hypertension and cardiac hypertrophy and dysfunction.

DFT investigation on the structural and vibrational behaviours of the non-protein amino acids in hybrid explicit/continuum solvent: a case of the zwitterions γ-aminobutyric and α - aminoisobutyric acids

BACKGROUND

The influence of hybrid solvation models on the molecular structures and vibrational characteristics of g-aminobutyric acid (GABA) and a-aminoisobutyric acid (AIB) zwitterions was assessed by employing a variety of Density Functional Theory (DFT). The quantum chemical methods included the B3LYP and B3PW91 hybrid functionals and the 6‑311++G(d,p) basis set.

METHODS

The most stable conformation derived from the potential energy surface (PES) scans using the B3LYP/6-311++G(d,p) model chemistry for each studied molecule was predicted within a continuum environment represented by the COSMO and SMD solvation models. The stable structures were subsequently immersed in explicit/COSMO and explicit/SMD hybrid solvation models, where 10 and 8 water molecules were explicitly positioned around the functional groups of the GABA and AIB zwitterions, respectively. The number of water molecules chosen was sufficient to prevent proton transfer among the carboxylate group (COO-) and the ammonium group (NH3+) within each molecule under investigation. After optimizing the geometry of each hydrated complex, the normal vibrational modes were determined. The scaled theoretical frequencies obtained from the various model chemistries were then compared to available experimental data from infrared (IR) and Raman spectroscopy.

RESULTS

In the case of GABA and AIB molecules, the comparisons revealed that the B3LYP/6-311++G(d,p) model chemistry yielded wavenumber values that closely matched the experimental IR and Raman data, particularly when the explicit/SMD solvent was employed. The computed results indicate deviations of less than 4% when compared to the experimental data for the two molecules under investigation.

Vibrational Spectroscopy, Quantum Computational and Molecular Docking Studies on 2-[(1H-Benzimidazol-1-yl)-methyl]benzoic Acid

Experimental and theoretical investigations on the optimized geometrical structure, electronic and vibrational features of 2-[(1H-benzimidazol-1-yl)-methyl]benzoic acid are provided using the B3LYP/6-311++G(d,p) basis set. The Vibrational Energy Distribution Analysis (VEDA) program was used to perform the vibrational assignments and calculate the Potential Energy Distribution (PED). The acquired FT-IR and FT Raman data were used to complete the vibrational assignment and characterization of the compound fundamental modes. Theoretical and actual NMR chemical shifts were found to be quite similar. The UV-vis spectrum of 21HBMBA, as well as effects of solvents, have been investigated. The calculated HOMO and LUMO energies reveal that charge transfer happens within the molecule and MEP surface to be a chemically reactive area appropriate for drug action. Furthermore, a thorough examination of Non-Bonding Orbitals, excitation energies, AIM charges, Fukui functions and the Electron Localization Function (ELF) is carried out. The research is also expanded to compute first-order hyperpolarizability and forecast NLO characteristics. The details of the docking studies aided in the prediction of protein binding.

Polycatecholamine and gentamicin as modifiers for antibacterial and blood-biocompatible polyester vascular prostheses

Polyester (PET) prostheses are commonly used in reconstructive vascular surgery. The most serious complication after implantation is early or late infection of the graft. Therefore, there is high demand to protect prosthesis against bacterial adhesion and biofilm development. For this reason, in this work PET prostheses were first coated by highly adhesive polycatecholamine layer. The grafts were then coupled with gentamicin and studied in relation to morphological and structural properties, biological safety (contact with blood, reaction of vascular endothelial cells (HUVEC), Danio rerio fish), drug release and antibacterial activity. Among two tested catecholamine monomers, L-DOPA was found to be more effective precursor in this process than dopamine. For L-DOPA, assistance of Cu²⁺, Mg²⁺ and Na⁺ ions seems to increase the amount of further immobilized drug. Coated prostheses exhibited greater human endothelial cell proliferation increase and lower cytotoxic effect than uncoated. The modification reduced the hemolysis observed for pristine commercial graft and limited the rate of abnormalities in D. rerio larvae, confirming the safety of the proposed modification. The coating allowed to double the amount of immobilized antibiotic in comparison with uncoated graft which resulted in increased antibacterial activity and reduced bacterial adhesion against 4 bacterial strains prevalent in biomaterials infections. Overall, poly(L-DOPA)-coatings deposited on PET vascular grafts can effectively functionalize these prostheses for higher safety in biomedical applications.

Inclusion of Levodopa into β-Cyclodextrin: A Comprehensive Computational Study

This study focused on the inclusion of levodopa (LVDP) into β-cyclodextrin (BCD) using various computational methods such as quantum mechanics (QM), molecular dynamics/steered molecular dynamics (MD/SMD), and QM/molecular mechanics/Poison-Boltzmann surface area (QM/MM/PBSA). The QM results assigned the most significant charge-transfer atoms and the higher stability of LVDP in the aqueous phase. The MD results indicate the formation of a 1:1 complex with a reasonable estimation of the effective radius of the complex, the significant contribution of hydrogen bonding in the binding energy, and the enhancement of the water solubility of LVDP. By accounting for the water hydrogen bonds and their dipolar effects, QM/MM calculations lead to the more accurate IR spectrum and binding energy of the BCD-LVDP complex. By considering carboxylic and amine functional groups' more precise arrangement, QM/MM assigns stronger hydrogen bonds between LVDP and BCD. While all the methods provide a reasonable estimation of the binding energy, the most accurate value (-4.14 kcal/mol) is obtained from QM/MM/PBSA.

Designing Silver Nanoparticles for Detecting Levodopa (3,4-Dihydroxyphenylalanine, L-Dopa) Using Surface-Enhanced Raman Scattering (SERS)

Detection of the drug Levodopa (3,4-dihydroxyphenylalanine, L-Dopa) is essential for the medical treatment of several neural disorders, including Parkinson's disease. In this paper, we employed surface-enhanced Raman scattering (SERS) with three shapes of silver nanoparticles (nanostars, AgNS; nanospheres, AgNP; and nanoplates, AgNPL) to detect L-Dopa in the nanoparticle dispersions. The sensitivity of the L-Dopa SERS signal depended on both nanoparticle shape and L-Dopa concentration. The adsorption mechanisms of L-Dopa on the nanoparticles inferred from a detailed analysis of the Raman spectra allowed us to determine the chemical groups involved. For instance, at concentrations below/equivalent to the limit found in human plasma (between 10-7-10-8 mol/L), L-Dopa adsorbs on AgNP through its ring, while at 10-5-10-6 mol/L adsorption is driven by the amino group. At even higher concentrations, above 10-4 mol/L, L-Dopa polymerization predominates. Therefore, our results show that adsorption depends on both the type of Ag nanoparticles (shape and chemical groups surrounding the Ag surface) and the L-Dopa concentration. The overall strategy based on SERS is a step forward to the design of nanostructures to detect analytes of clinical interest with high specificity and at varied concentration ranges.

Interaction Studies Between Levodopa and Different Excipients to Develop Coground Binary Mixtures for Intranasal Application

Levodopa (LEVO) as the gold standard in the treatment of Parkinson's disease is usually administrated per os but its bioavailability is low. The intranasal administration is a potential alternative route to increase bioavailability of the drug and treat the off period. Our aim was to develop LEVO-containing binary nasal powders with different excipients by dry cogrinding process. The interactions between the components were examined. The optimized cogrinding process parameters (LEVO:excipient ratio and grinding time) resulted in the desired particle size range (5-40 μm). The α-cyclodextrin and poly(vinylpyrrolidone) (PVP) had an intensive crystallinity degree reducing effect on LEVO measured by XRPD, and they functioned as cogrinding agents. Hydroxypropyl methylcellulose, poly (vinyl alcohol) (PVA), and D-mannitol associate around the LEVO crystals preventing its crystalline structure. Hydrogen bonding was detected only for LEVO-PVP and LEVO-D-mannitol used Fourier-transformed infrared spectroscopy. Chemical degradation of LEVO in the products was not detected even after the accelerated stability test. The dissolution profile of the products can be characterized by the first-order kinetic model with different dissolution rate. The dissolution rate of LEVO was increased with α-cyclodextrin and PVP, and the drug release decreased in the case of hydroxypropyl methylcellulose, PVA, and D-mannitol compared to the LEVO powder.

Antiradical activity of catecholamines and metabolites of dopamine: theoretical and experimental study

The importance of molecules with antiradical potency that are produced in the human body has significantly increased. Among others, neurotransmitters and their metabolites act as the first line of defense against oxidative stress in the peripheral endocrine and the central nervous systems. Dopamine (DO), epinephrine (EP), norepinephrine (NE), l-DOPA, catechol, and three metabolites of dopamine (3-methoxytyramine (3-MT), homovanillic acid (HO), and 3,4-dihydrophenylacetic acid (DOPAC)) were investigated for their antiradical potency via computational methods and DPPH assay. Density functional theory calculations were used to determine the most probable reaction mechanism based on the thermodynamic parameters. These results suggested that hydrogen atom transfer (HAT)/proton-coupled electron transfer (PCET) and sequential proton loss electron transfer (SPLET) mechanisms are preferable in polar solvents. Several techniques were employed to differentiate between HAT and PCET mechanisms via examination of the transition state structures. Kinetic studies of HAT/PCET and electron transfer (ET) reactions, the second step of SPLET, have proven that ET is much faster for an order of 10⁵-10⁶. Based on this, it was concluded that SPLET was the dominant mechanism for the antiradical activity towards DPPH radicals in polar solvents. The findings suggest that all the investigated molecules can be classified as excellent antiradical scavengers, except for 3-MT and homovanillic acid.

Quantum chemical studies on structural, vibrational, NBO and hyperpolarizability of N-(1,1-Dimethyl-2-hydroxyethyl)-3-amino-2-hydroxypropanesulfonic acid

The FTIR and FT-Raman spectra of N-(1,1-Dimethyl-2-hydroxyethyl)-3-amino-2-hydroxypropanesulfonic acid were recorded in the regions 4000-400cm(-1) and 4000-50cm(-1) respectively. The structural and spectroscopic data of the molecule in the ground state were calculated using Hartee-Fock and density functional method (B3LYP) with the correlation consistent-polarized valence double zeta (cc-pVDZ) basis set. The most stable conformer was optimized and the structural and vibrational parameters were determined based on this. With the observed FTIR and FT-Raman data, a complete vibrational assignment and analysis of the fundamental modes of the compound were carried out. Thermodynamic properties and Mulliken charges were calculated using both Hartee-Fock and density functional method using the cc-pVDZ basis set and compared. The calculated HOMO-LUMO energy gap revealed that charge transfer occurs within the molecule. (1)H and (13)C NMR chemical shifts of the molecule were calculated using Gauge Including Atomic Orbital (GIAO) method and were compared with experimental results. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. The first order hyperpolarizability (β) and Molecular Electrostatic Potential (MEP) of the molecule was computed using DFT calculations. The electron density based local reactivity descriptor such as Fukui functions were calculated to explain the chemical reactivity site in the molecule.

Molecular structure, vibrational spectra, NBO, UV and first order hyperpolarizability, analysis of 4-Chloro-dl-phenylalanine by density functional theory

The Fourier transform infrared (4000-400cm(-1)) and Fourier transform Raman (3500-50cm(-1)) spectra of 4-Chloro-dl-phenylalanine (4CLPA) were recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational wavenumbers were investigated with the help of density functional theory (DFT) method using B3LYP/6-31G(d,p) as basis set. The observed vibrational wavenumbers were compared with the calculated results. Natural bond orbital analysis confirms the presence of intramolecular charge transfer and the hydrogen bonding interaction. Predicted electronic absorption spectra from TD-DFT calculation have been analyzed comparing with the UV-Vis (200-800nm) spectrum. The effects of chlorine and ethylene group substituent in benzene ring in the vibrational wavenumbers have been analyzed. The HOMO-LUMO energy gap explains the charge interaction taking place within the molecule. The first order hyperpolarizability (β0) and related properties (β, α0 and Δα) of 4CLPA were calculated. The Chemical reactivity and chemical potential of 4CLPA is calculated. In addition, molecular electrostatic potential (MEP), frontier molecular orbital (FMO) analysis were investigated using theoretical calculations.

FT-Raman, FT-IR and UV-visible spectral investigations and ab initio computations of anti-epileptic drug: vigabatrin

Vibrational analysis of anti-epileptic drug vigabatrin, a structural GABA analog was carried out using NIR FT-Raman and FTIR spectroscopic techniques. The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers were studied using density functional theory method. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA.4 program. Vibrational spectra, natural bond orbital analysis and optimized molecular structure show clear evidence for the effect of electron charge transfer on the activity of the molecule. Predicted electronic absorption spectrum from TD-DFT calculation has been compared with the UV-vis spectrum. The Mulliken population analysis on atomic charges and the HOMO-LUMO energy were also calculated. Good consistency is found between the calculated results and experimental data for the electronic absorption as well as IR and Raman spectra. The blue-shifting of the C-C stretching wavenumber reveals that the vinyl group is actively involved in the conjugation path. The NBO analysis confirms the occurrence of intramolecular hyperconjugative interactions resulting in ICT causing stabilization of the system.