Biomedical subjects

Padmakar V Khadikar

Publications and source records attributed to Padmakar V Khadikar.

At least 19 recordsLinked to original sources

PubMed2006

QSAR studies on benzopyran potassium channel activators.

QSAR studies on a series of benzopyrans as potassium channel activators have been carried out using a large set of distance-based topological indices. In addition, the molecular descriptors namely: negentropy and molecular redundancy indices have also been used. The relaxant potency in rat trachea, expressed as pEC(50) was used for biological characterization of the benzopyrans. The results have shown that pEC(50) can be modeled excellently in multiparametric model in that we have to include an indicator parameter. The predictive powers of the proposed models are discussed on the bases of cross-validation parameters.

Animals↗

PubMed2006

QSAR study on topically acting sulfonamides incorporating GABA moieties: a molecular connectivity approach.

A quantitative Structure-activity relationship study (QSAR) on a set of carbonic anhydrase (CA, EC 4.2.1.1) inhibitors is reported using first-order valence connectivity index ((1)chi(v)). The inhibitory activity against three isozymes CAI, CAII (cystolic forms), and CAIV (membrane bound form), some of which are involved in important physiological processes, were considered for this purpose. All the three activities were excellently modeled by (1)chi(v) in multi-parametric regression containing indicator parameters. The results are critically discussed on the basis of various regression parameters.

Carbonic Anhydrase Inhibitors↗

PubMed2005

Study on supramolecular complexing ability vis-à-vis estimation of pKa of substituted sulfonamides: dominating role of Balaban index (J).

The supramolecular complexing ability vis-à-vis pKa estimation of a large series of 43 sulfonamides was made using a series of molecular descriptors including topological indices. The set of topological indices chosen also contains Balaban (J) and a variety of Balaban type indices: J, Jz, Jm, Jv, Jc, and Jp. The results have shown that the most discriminating Balaban index (J) in multi-parametric regression analysis combined with indicator parameters yields excellent models and also establishes the superiority of the J index over other Balaban type indices. The statistics is improved when one of the indicator parameters is replaced by molar volume (MV). The results are discussed critically using a variety of statistics.

Macromolecular Substances↗

PubMed2005

QSAR study on carbonic anhydrase inhibitors: water-soluble sulfonamides incorporating beta-alanyl moieties, possessing long lasting-intra ocular pressure lowering properties--a molecular connectivity approach.

A QSAR study on a series of carbonic anhydrase (CA, EC 4.2.1.1) inhibitors, and more precisely on water-soluble sulfonamides incorporating beta-alanyl moieties, possessing long lasting intra-ocular pressure lowering properties, was carried out using a series of distance-based topological indices. The regression analysis has shown that out of the pool of topological indices used, the 1chi (first-order Randic connectivity index) is the best one for modeling CA inhibitory properties against all three investigated isozymes, the cytosolic CA I, CA II and the membrane-bound CA IV, and that excellent results are obtained in multiparametric regressions. The results are critically discussed on the basis of statistical parameters.

Alanine↗

PubMed2005

A novel method of estimation of lipophilicity using distance-based topological indices: dominating role of equalized electronegativity.

Attempt is made to propose yet another method of estimating lipophilicity of a heterogeneous set of 223 compounds. The method is based on the use of equalized electronegativity along with topological indices. It was observed that excellent results are obtained in multiparametric regression upon introduction of indicator parameters. The results are discussed critically on the basis various statistical parameters.

Electrons↗

PubMed2005

QSAR studies on benzene sulfonamide carbonic anhydrase inhibitors: need of hydrophobic parameter for topological modeling of binding constants of sulfonamides to human CA-II.

The binding constants (logK) of benzene sulfonamides to human CA-II have been modeled using a large series of distance-based topological indices. The need or otherwise of the hydrophobic parameter (logP) for such topological modeling of logK has been examined critically. In both the cases excellent results have been obtained. In multiparametric models involving indicator parameters we observed that introduction of hydrophobic parameter (logP) yields much improved statistics. The results are discussed on the basis of statistical parameters and also by using cross-validation method.

Benzene Derivatives↗

PubMed2005

Novel use of chemical shift in NMR as molecular descriptor: a first report on modeling carbonic anhydrase inhibitory activity and related parameters.

A novel use of NMR chemical shift of the SO(2)NH(2) protons (in dioxane as solvent) as a molecular descriptor is described for modeling the inhibition constant for benzene sulfonamides against the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1). The methodology is extended to model diuretic activity and lipophilicity of benzene sulfonamide derivatives. The regression analysis of the data has shown that the NMR chemical shift is incapable of modeling lipophilicity. However, it is quite useful for modeling the diuretic activity of these derivatives. The results are compared with those obtained using distance-based topological indices: Wiener (W)-, Szeged (Sz)-, and PI (Padmakar-Ivan) indices.

Benzene Derivatives↗

PubMed2005

Novel estimation of lipophilicity using 13C NMR chemical shifts as molecular descriptor.

This paper describes the use of (13)C NMR chemical shift as molecular descriptor (molecular parameter) for modeling lipophilicity (logP). A set of 32 alcohols were chosen for this purpose. The regression analysis of the data showed that (13)C NMR chemical shifts of these alcohols can be used as a molecular descriptor (molecular property) for modeling the lipophilicity (logP). Better results are obtained by introducing an indicator parameter.

Carbon Isotopes↗

PubMed2005

QSAR study on the antibacterial activity of some sulfa drugs: building blockers of Mannich bases.

Sulfa drugs are building blockers of several types of Mannich bases. Consequently, the antibacterial activities of sulfa drugs are reported in this paper, which will help in explaining and understanding antibacterial activities of Mannich bases. Reported QSAR is carried out using distance-based topological indices and discussed critically on the basis of statistical parameters.

Anti-Bacterial Agents↗

PubMed2005

QSAR study on pK(a) vis-à-vis physiological activity of sulfonamides: a dominating role of surface tension (inverse steric parameter).

The paper describes the dominating role of surface tension (ST) on the modeling, monitoring, and estimating pK(a) for a large series of 43 substituted sulfonamides. Because of the direct correlation of ST with parachor (Pc) vis-a-vis molecular volume (MV), ST is considered as a steric parameter. Single as well as multi-parametric regressions have indicated that ST has a dominating role in QSAR of the set of sulfonamides used and that excellent results are obtained in multi-parametric regression analysis. The results are discussed critically on the basis of statistical parameters.

Quantitative Structure-Activity Relationship↗

PubMed2004

Topological modeling of lipophilicity, diuretic activity, and carbonic inhibition activity of benzene sulfonamides: a molecular connectivity approach.

A large series of distance-based topological indices has been used for modeling lipophilicity, diuretic activity, and carbonic anhydrase inhibition activity of a library of simple substituted benzene sulfonamides. The results have shown that the topological approach used is quite useful for modeling carbonic anhydrase inhibition and the use of molecular connectivity is the best for this purpose. Excellent results are obtained in multiparametric regressions. The results are critically discussed on the basis of statistical parameters.

Benzene Derivatives↗

PubMed2004

Topological estimation of electronic absorption bands of arene absorption spectra as a tool for modeling their toxicity and environmental pollution.

A novel application of distance-based topological indices : Wiener (W)-, Szeged (Sz)-, Padmakar-Ivan (PI)-, and Sadhana (Sd)-indices in modeling electronic absorption bands of arene absorption spectra has been described. It is demonstrated that all these indices correlate linearly with the logarithm of beta and para electronic absorption bands in several series of arene systems. The results have shown that our methodology is best suited for the estimation--lnlambda(beta), while comparatively less significant results are obtained in case of the estimation of lnlambda(p). The statistical analysis of the data have shown that PI index gives better results for modeling lnlambda(beta); while Sz index proved better for modeling lnlambda(p). The results are critically discussed on the basis of regression parameters and quality of correlation. Such a study will be useful as a tool for modeling toxicity of arene system as well as their environmental pollution.

Electrochemistry↗

PubMed2004

Carbonic anhydrase inhibitors: the first QSAR study on inhibition of tumor-associated isoenzyme IX with aromatic and heterocyclic sulfonamides.

QSAR study on the tumor-associated transmembrane carbonic anhydrase IX (CA IX) isoenzyme has been made using a large pool of distance-based topological indices : W, Sz, PI (0)chi, (1)chi, (2)chi,(0)chi(v), (1)chi(v), (2)chi(v). A combined set of 32 aromatic and heterocyclic compounds, including the six clinically used derivatives: acetazolamide, methazolamide, ethoxyzolamide, dichlorophenamide, dorzolamide, and brinzolamide are used for this purpose. The results have shown that the inhibition of the tumor-associated isoenzyme IX with aromatic and heterocyclic sulfonamides can be modeled excellently in multiparametric regression after introduction of indicator parameters. The predictive power of the models is discussed using probable error of correlation (PE), variance-inflation factor (VIF), and cross-validation parameters: PRESS, SSY, r(2) (cv) (S) PRESS, and PSE. This is the first report on QSAR study on inhibition of tumor-associated isoenzyme IX.

Antigens, Neoplasm↗

PubMed2004

QSAR study on CA inhibitory activity of disulfonamides: effect of halogen substitution.

The paper deals with quantitative structure-activity relationship (QSAR) study on CA inhibitory activity (logIC(50)) of disulfonamides using a large series of distance-based topological indices. The study discusses effect due to halogen-substitution nearer (o-position) to -SO(2)NH(2) groups. The results have shown that halogen substitution at R(3) has pronounced effect on the inhibitory activity. Predictive power of the proposed models is discussed on the basis of regression data and cross-validation parameters.

Carbonic Anhydrase Inhibitors↗

PubMed2004

QSAR study on phenolic activity: need of positive hydrophobic term (log P) in QSAR.

The phenolic activity (log 1/C) of a large series of phenols against L1210 leukaemia cells was modelled using physicochemical parameters other than conventional electronic and steric parameters. Attempts have also been made to examine need or otherwise of the hydrophobic parameter, log P, in such studies. The results have shown that contribution of log P in modelling log 1/C is favourable.

Animals↗

PubMed2004

Correlations between the benzene character of acenes or helicenes and simple molecular descriptors.

Aromatic stabilities of acenes and helicenes, which are responsible for their biological, environmental and cancerous behavior have been modeled using a newly introduced Sadhana (Sd) and A indices. The results are compared with those obtained from PI (Padmakar-Ivan) index. The regression analysis has shown that excellent results are obtained by considering acenes and helicenes as separate classes of isomeric benzenoid hydrocarbons and that A index is better index than both PI and Sd indices.

Benzene↗

PubMed2004

QSAR studies on psychotomimetic phenylalkylamines.

Quantitative Structure-Activity Relationship (QSAR) studies on a series of psychotomimetic phenylalkylamines have been made using a combination of Minimum Topological Difference (MTD) method and topological methodology. The topological indices used being a pool of distance-based topological indices. The regression analyses have shown that excellent results are obtained in multiparametric model containing MTD parameters, topological indices in that quantum chemical parameters has to be introduced. The predictive power of the proposed model is discussed on the basis of cross-validation parameters.

Aniline Compounds↗

PubMed2004

QSAR study on benzenesulphonamide carbonic anhydrase inhibitors: topological approach using Balaban index.

QSAR study on benzenesulphonamide carbonic anhydrase inhibitors has been made using the most discriminatory Balaban index (J). The regression analysis has shown that even in monoparametric regression this index gave excellent results. Furthermore, using the combination of the Balaban Index (J) with the first-order Randic connectivity index ((1)chi) and indicator parameters, tremendous improvement in the statistics has been observed. The results are critically discussed on the basis of regression data and cross-validation parameters.

Carbonic Anhydrase Inhibitors↗