Search

Fullerenes have received attentions due to their versatile properties. Molecular structures and electronic properties namely binding energy, band gap, electrophilicity index and molecular topological analysis were studied for undoped and silicon doped C20 fullerenes and favipiravir in order to search for possible application of the systems as drug delivery vehicles. Density functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) were used for the research. Molecular structures having the interaction edges of SiC19… OH in water and SiC19…C=O in gas phase were found as those most stable with binding energies of -57.28 kcal/mol and -43.46 kcal/mol correspondingly. The results and parameters found in this research may provide additional insights into drug delivery systems.

Fullerenes, with their extensive application potentials, have been receiving attention for their possible usage as drug delivery vehicles and devices for sensor technologies. In this work, the optimized molecular geometries, some diagnostic geometric parameters, electronic characteristics, natural bond orbital examinations and the interaction phenomena between C60, Si- or Al-doped C60 and phenylalanine amino acid molecule were investigated by the quantum mechanical calculations. It is observed that the impurity addition and using water as the solvent intensify the interaction between fullerene and amino acid system. These lead to various alterations in the electronic properties and NH stretching values of the clusters studied.

1-(3-trifluoromethylphenyl)piperazine (TFMPP) is one of the commonly abused drugs in the illicit drug market. Its detection or identification is important to investigate. In this work, density function theory (DFT) approach was used to analyse silicon or aluminium doped C60 fullerenes and TFMPP interactions for possible sensor applications. Stabilities of the investigated systems were examined in terms of the adsorption energies of TFMPP onto Si and Al decorated fullerenes. It was found that AlC59+TFMPP resulted in higher adsorption energies compared to SiC59+TFMPP. We also considered the band gap energy and concluded that Si and Al decorated fullerenes are sensitive to the presence of TFMPP in both the gas phase and aqueous medium.

Fullerenes and heteroatom doped fullerenes exhibit high potential as drug delivery agents in sensor technology and medical applications. We investigated, using density functional theory, the possible interaction sites and the nature of interaction, adsorption energy assessments, band gap energy evaluations, charge transfer analyses, and some diagnostic vibrational band assignments for valproic acid (VPA) and aluminum, silicon, and boron decorated fullerene systems. The present research shows that VPA has strong interaction with the doped fullerene cages particularly at its carbonyl edge. Therefore, these doped fullerenes can be suggested as possible drug delivery agents.

Piperazine and tetraone-related compounds are widely used in the drug industry. Heteroatom-doped fullerenes are studied as new types of sensor devices, and medical applications are studied as drug delivery vehicles. In this work, Si- or Al-doped C60 fullerenes and their interactions with piperazine-2,3,5,6-tetraone (ppto) molecule and some important structural or electronic properties were examined using the density functional theory (DFT). Results indicate that doped C60 fullerenes might be used to diagnose the presence of ppto as delivery vehicle and sensor because of their high adsorption energies and change of band gap energies.

Piperazines and fullerene nanocages are versatile compounds. These are discussed in a wide range of academic work, especially in the field of medicine, and considered for various applications by the pharmaceutical industry. In the present research, the potential interaction mechanisms between B-, Si-doped C60 and 1-formylpiperazine (1-fp) were examined within the framework of density functional theory, along with their optimized molecular structures and electronic properties. The calculated binding energies and various other physical and chemical parameters of 1-fp found in this work in comparison with the Si- and B-doped fullerenes suggest that doping of fullerene nanocage leads to a strong interaction mechanism that alters the chemical and electronic properties of the investigated compounds. This finding can be used as a guide for their further applications.

A large number of drugs are introduced each year to treat different diseases. Most of the time, patients suffer from more than one health problem which makes it necessary to take multiple drugs. When drugs are combined, the problem of drug-drug interaction becomes relevant. In this work, we studied the drug-drug interaction between escitalopram and ibuprofen or paracetamol using density functional theory and quantum theory of atoms in molecules. The results suggest that following the interactions, the activity of drugs changes according to site of interaction. Most reactive and most stable interactions would be preferable for the purpose of use. The in silico drug-likeness studies show that escitalopram and paracetamol couple is more bioavailable than escitalopram and ibuprofen couple. Moreover, in order to gain additional insights into the mentioned drugs' interactions, the drugs were docked separately and jointly against the potential targets for antidepressants and NSAIDs, namely 6HIS and 2PXX . The molecular docking results showed a potential improvement of the effectiveness of the drugs after combining by forming hydrogen bonds, hydrophobic contacts and π…π stacking.Communicated by Ramaswamy H. Sarma.

One of the approaches adopted, as the first treatment method, in previous pandemic viruses before the production of new vaccines or drugs, is to evaluate the effectiveness of existing drugs. Sometimes, it is known that the combination of drugs provides better treatment by increasing the activity of the drugs due to mutual interactions. In this work, we used quantum theory of atoms in molecules and density functional theory to examine the structure and activity relationship between Favipiravir (FPV), a potential antiviral drug for ribonucleic acid viruses, and an inhibitor of influenza virus, and Ibuprofen (IBP), a nonsteroidal anti-inflammatory drug. The drug-likeness evaluations of IBP…FPV were also performed. It was observed that FPV and IBP interact in several ways via hydrogen bonding (HB) leading to changes in the activities of the combined drug and IBP…FPV is predicted to be orally bioavailable. It was also found that the highest occupied molecular orbital (HOMO) is located on IBP and the lowest unoccupied molecular orbital (LUMO) is distributed over FPV. The biological activity of the combined drug system is increased because of the small HOMO-LUMO energy gap value, partially covalent and non-covalent HB interactions.Communicated by Ramaswamy H. Sarma.

Hydroxychloroquine (HCQ) and favipiravir (FPV) are known to be effective antivirals, and there are reports about their use to fight the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) despite that these are not conclusive. The use of combined drugs is common in drug discovery, and thus, we investigated HCQ and FPV as a combined drug. The density functional theory method was used for the optimization of geometries, spectroscopic analysis and calculation of reactivity parameters. The quantum theory of atoms in molecules was applied to explain the nature of the hydrogen bonds and confirm the higher stability of the combined drug. We also evaluated the absorption, distribution, metabolism and excretion (ADME) parameters to assess their drug actions jointly using SwissADME. The preliminary findings of our theoretical study are promising for further investigations of more potent and selective antiviral drugs., Supplementary Information: The online version contains supplementary material available at 10.1007/s11696-021-01946-8., Competing Interests: Conflict of interestsOn behalf of all authors, the corresponding author states that there is no conflict of interest., (© Institute of Chemistry, Slovak Academy of Sciences 2021.)

The proverb "Old is gold" is applicable in drug discovery and the proverb "All that Glitters is not Gold" is also appropriate. In the COVID-19 era, there has been a race for drugs to be effective against SARS-CoV-2. There are reports about the uses of Remdesivir and Favipiravir as existing antivirals against virus but none have been conclusive so far. In the attempts for innovations, the combination of drugs is also under trials. Therefore, we used the density functional theory method and quantum theory of atoms in molecules to investigate drug-drug interactions involving Remdesivir and Favipiravir. The computed parameters were related to the antiviral actions of both drugs together. The results indicate enhanced antiviral activity and it will be worthy to consider additional investigations with the combination of these two drugs., Competing Interests: The authors declare that no conflicts of interest exist., (Thieme. All rights reserved.)

Infrared and Raman spectra of 1-pyrrolidino-1-cyclohexene (1pych) have experimentally been reported in the region of 4000-100 cm(-1). The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1pych (C10H17N) have theoretically been examined by means of the Becke-3-Lee-Yang-Parr (B3-LYP) density functional theory (DFT) method together with the 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments have been made the basis of potential energy distribution (PED) and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of 1pych have been predicted. Angular distribution of the probability density of populations of its conformational isomers is determined by analysis of the potential energy surface (PES). Comparison between the experimental and theoretical results indicates that B3-LYP method is provides satisfactory results for the prediction vibrational wavenumbers and structural parameters and the mixture of envelope and twist conformers is supposed to be the most stable form of 1pych., (Copyright © 2013 Elsevier B.V. All rights reserved.)

FT-IR and Raman spectra of 1-pyrrolidino-1-cyclopentene (1py1cp) were experimentally reported in the region of 4000-10 cm(-1) and 4000-100 cm(-1), respectively. The optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of 1py1cp (C9H15N) were theoretically examined by means of the B3LYP hybrid density functional theory (DFT) method together with the 6-31++G(d,p) basis set. Furthermore, reliable vibrational assignments were made on the basis of the potential energy distribution (PED) and the thermodynamics functions, the highest occupied and the lowest unoccupied molecular orbitals (HOMO and LUMO) of 1py1cp were predicted. Calculations were carried out employed for three different conformations of 1py1cp in gas phase. Comparison between the experimental and theoretical results indicates that density functional B3LYP method is able to provide satisfactory results for predicting vibrational wavenumbers and envelope conformer is predicted to be the most stable conformer of 1py1cp., (Copyright © 2012 Elsevier B.V. All rights reserved.)