Semi-empirical calculations including an empirical dispersive correction are used to calculate intermolecular interaction energies and structures for a large database containing 156 biologically relevant molecules (hydrogen-bonded DNA base pairs, interstrand base pairs, stacked base pairs and amino acid base pairs) for which MP2 and CCSD(T) complete basis set (CBS) limit estimates of the intera...

The simulation of enzymatic reactions, using computer models, is becoming a powerful tool in the most fundamental challenge in biochemistry: to relate the catalytic activity of enzymes to their structure. In the present study, various computed parameters were correlated with the natural logarithm of experimental rate constants for the hydroxylation of various substrate derivatives catalysed by ...

Several quantum-mechanics-based descriptors were derived for a diverse set of 48 organic compounds using AM1, PM3, HF/6-31+G, and DFT-B3LYP/6-31+G (d) level of the theory. LC50 values of acute toxicity of the compounds were correlated to the fathead minnow and predicted using calculated descriptors by employing Comprehensive Descriptors for Structural and Statistical Analysis (CODESSA) program....

The intermolecular forces between anti–cancer molecules such as Cisplatin, Carboplatin, Oxaliplatin, Nedaplatin, Lobaplatin, Heptaplatin, Dicycloplatin, Eleutherobin, Epothilone B, Discodermolide and Taxol (Figures 1 and 2) and tumor multiple organs or tissues are of great importance in many areas of science including medicine, chemotherapy, pharmacology, medicinal chemistry, pharmaceutical che...

The molecular orbital calculations have been carried out to investigate the structure and stability of (E) / (Z) isomers of some azobenzene derivatives containing maleimide groups. A special attention has been devoted to the compound (E)-1, (E)-1-(4-(phenyldiazenyl)phenyl)-1H-pyrrole-2,5-dione, for which the available crystallographic experimental data have been used to validate the modeling st...

The quality of quantitative structure-activity relationship (QSAR) models depends on the quality of their constitutive elements including the biological activity, statistical procedure applied, and the physicochemical and structural descriptors. The aim of this study was to assess the comparative use of ab initio and semiempirical quantum chemical calculations for the development of toxicologic...

A combined quantum mechanical (QM) and molecular mechanical (MM) potential has been developed for the study of reactions in condensed phases. For the quantum mechanical calculations semiempirical methods of the MNDO and AM1 type are used, while the molecular mechanics part is treated with the CHARMM force field. Specific prescriptions are given for the interactions between the QM and MM portion...

objective: to evaluate the effect of niprd-am1 on cyp3a4 in order to generate clinically significant data for its safe and efficacious use. materials and methods: niprd-am1 is a phytomedicine developed from aqueous root extracts of nauclea latifolia smith (rubiaceae) for the treatment of uncomplicated malaria. the effect of niprd-am1 on cyp3a4 was measured with and without the addition of niprd...

A common practice to compute ligand conformations of compounds with various degrees of freedom to be used in molecular modeling (QSAR and docking studies) is to perform a conformational distribution based on repeated random sampling, such as Monte-Carlo methods. Further calculations are often required. This short review describes some methods used for conformational analysis and the implication...

OBJECTIVE To evaluate the effect of NIPRD-AM1 on CYP3A4 in order to generate clinically significant data for its safe and efficacious use. MATERIALS AND METHODS NIPRD-AM1 is a phytomedicine developed from aqueous root extracts of Nauclea latifolia Smith (Rubiaceae) for the treatment of uncomplicated malaria. The effect of NIPRD-AM1 on CYP3A4 was measured with and without the addition of NIPRD...