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S C Basak

Publications and source records attributed to S C Basak.

At least 19 recordsLinked to original sources
PubMed2000

A comparative QSAR study of benzamidines complement-inhibitory activity and benzene derivatives acute toxicity.

A novel QSAR study of benzamidines complement-inhibitory activity and benzene derivatives acute toxicity is reported and a new efficient method for selecting descriptors is used. Complement-inhibitory activity QSAR models of benzamidines contain from one to five descriptors. The best, according to fitted and cross-validated statistical parameters, is shown to be the five-descriptor model. Models with a higher number of indices did not improve over the five-descriptor model. The benzene derivatives structure-toxicity models involve up to seven linear descriptors. Multiregression models, containing up to ten nonlinear descriptors, are also reported for the sake of comparison with previously obtained additivity models. Comparison with benzamidine complement-inhibitory activity models and with benzene derivatives toxicity models from the literature favors our novel approach.

Animals↗
PubMed2000

Multiple regression analysis with optimal molecular descriptors.

We consider construction of optimal molecular descriptors to be used for multiple regression analysis of several properties of alcohols. The descriptors are obtained by considering shorter paths with variable weight x for carbon-oxygen bond in alcohol. In particular we consider as molecular descriptors paths of length 1, 2 and 3. The multiple regression analysis of the following molecular properties was examined: - log S (S = solubility), CSA (cavity surface area), log P (P = octanol/water partition), and log gamma (gamma = infinite solution activity coefficient). By minimizing the standard error of the regression for each property we found optimal variable weight.

Alcohols↗
PubMed1999

Prediction of the dermal penetration of polycyclic aromatic hydrocarbons (PAHs): a hierarchical QSAR approach.

Attempts were made to develop hierarchical quantitative structure-activity relationship (QSAR) models for the dermal penetration of polycyclic aromatic hydrocarbons (PAHs) using four classes of theoretical structural parameters; viz., topostructural, topochemical, geometric, and quantum chemical descriptors; and physicochemical properties such as molecular weight (MW) and lipophilicity (log P--octanol/water). The results show that topostructural, topochemical, and geometric descriptors and molecular weight are equally effective in predicting the dermal penetration of PAHs. Quantum chemical parameters did not make any improvements in the predictive power of the QSAR models.

Animals↗
PubMed1997

Predicting acute toxicity (LC50) of benzene derivatives using theoretical molecular descriptors: a hierarchical QSAR approach.

Four classes of theoretical structural parameters, viz., topostructural, topochemical, geometrical and quantum chemical descriptors, have been used in the development of quantitative structure-activity relationship (QSAR) models for a set of sixty-nine benzene derivatives. None of the individual classes of parameters was very effective in predicting toxicity. A hierarchical approach was followed in using a combination of the four classes of indices in QSAR model development. The results show that the hierarchical QSAR approach using the algorithmically derived molecular descriptors can estimate the LC50 values of the benzene derivatives reasonably well.

Algorithms↗
PubMed1996

Predicting blood-brain transport of drugs: a computational approach.

PURPOSE: This study was conducted to determine the efficacy of using nonempirical parameters in the estimation of blood-brain transport, inferred from central nervous system (CNS) activity, for a set of twenty-eight compounds. METHODS: A discriminant function analysis was used to construct three distinct models based on topological indices, a hydrogen-bonding parameter, and logP. RESULTS: These models correctly predict the CNS activity of twenty-seven of the twenty-eight compounds. CONCLUSIONS: Nonempirical parameters may be used effectively in the estimation the cerebrovascular penetration for known and newly designed drugs.

Blood-Brain Barrier↗
PubMed1996

Characterization and immunoprotective properties of a monoclonal antibody against the major oocyst wall protein of Eimeria tenella.

The oocyst wall of Eimeria spp. consists of a 10-nm-thick outer lipid layer and a 90-mm-thick inner layer of glycoprotein which has been described previously to be composed of a single major protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions and (125)I labelling of a oocyst wall fragments and of delipidated intact oocysts revealed a molecule of approximately 12 kDa as the major protein component of the oocyst wall of Eimeria tenella. An immunoglobulin M monoclonal antibody (c11B9F3) was produced against this 12-kDa oocyst wall protein sliced from a preparative SDS-polyacrylamide gel. Its reactivity by immunofluorescence against oocyst wall fragments and sporozoites or by immunoperoxidase assays of infected tissue sections was stage restricted to gametocytes and oocysts but pan-specific against all face of the oocyst wall. In chicks passively immunized with C11B9F3, oocyst output was significantly (P<0.01) reduced by 42 to 54% after homologous E. tenella infection and by 35% after heterologous Eimeria maxima infection compared with that of control groups. The results demonstrate the presence of a highly conserved, low-molecular-weight antigen on the oocyst wall and the gametocytes of Eimeria spp. which is a candidate for inclusion in a pan-specific, transmission-blocking vaccine against avian coccidiosis.

Animals↗
PubMed1995

Predicting mutagenicity of chemicals using topological and quantum chemical parameters: a similarity based study.

Five molecular similarity methods have been used to estimate mutagenicity of a set of 73 aromatic and heteroaromatic amines. Two of the similarity methods (AP, PCTI) are based on topological parameters. Two other methods (PCPROP, PROP) are derived from physicochemical and electronic parameters. The fifth method, PCALL, is based on a combination of both topological and physicochemical parameters. The effectiveness of the five similarity methods in the rapid evaluation of mutagenicity is discussed.

Amines↗
PubMed1995

Use of graph theoretic parameters in risk assessment of chemicals.

In many instances of risk assessment, one has to estimate the potential risk of chemicals using limited experimental data, or no empirical data at all. In such cases, the use of non-empirical parameters, which can be calculated directly from structure, is a viable option for the risk assessor. Graph invariants have been used in predicting properties of congeneric sets of chemicals and determining structural similarity/dissimilarity of molecules. In this paper we have used (a) topological parameters in predicting mutagenicity of a diverse set of 520 chemicals and (b) graph theoretic parameters in quantifying structural similarity for a selection of analogs. The results of these analyses are presented along with a critical discussion of the utility and limitations of these methods.

Data Interpretation, Statistical↗
PubMed1995

Tolerance space and molecular similarity.

Molecular similarity methods were used in selecting K nearest neighbors and in estimating mutagenicity of 95 aromatic amines and boiling points of a large set of over 2,900 compounds. Similarity is analyzed in terms of the concept of tolerance space. Specifically, the role of non-transitivity of the tolerance relation in estimating properties using similarity methods is examined.

Amines↗
PubMed1984

Comparative study of lipophilicity versus topological molecular descriptors in biological correlations.

This paper analyzes the relative efficacies of lipophilicity vis-à-vis topological indices in the correlation of the biological properties of four groups of bioactive molecules: alcohols, barbiturates, triazinones , and ketobemidones . Wiener number (W), information-theoretic topological parameters (IC, SIC, CIC, IWD , and IWD ), and molecular connectivity indices (1 chi, 1 chi V) were used as the molecular descriptors. Results show that theoretical indices are comparable or superior to log P in biological correlations.

Alcohols↗
PubMed1983

Physicochemical and topological correlates of the enzymatic acetyltransfer reaction.

The relative potencies of a series of substituted anilines as acetyl acceptors in the enzymatic N-acetylation reaction have been correlated using physiochemical substituent constants (pi, sigma-), molecular connectivity indices (1 chi, 1 chi v), and newly formulated information-theoretic topological indices (IC, SIC). Results indicate a predominant role of the topological steric parameters in determining the rates of the N-acetyltransferase reaction.

Acetyltransferases↗
PubMed1982

Molecular connectivity and antifungal activity. A quantitative structure-activity relationship study of substituted phenols against skin pathogens.

The plot of minimum inhibitory concentration (MIC) vs. 2Xv of twelve phenolic compounds delineates the congeners into three distinct classes: the most potent ortho compounds describe a parabola, para substituted compounds of intermediate potency lie in a line, while the least potent meta derivatives yield a scatter diagram. The same pattern is found for two skin pathogens, Trichophyton rubrum and Epidermophyton floccosum. From non-linear regression analysis 2Xv is found to be excellently correlated with observed MIC values of the most potent ortho compounds against both the test organisms. For both the organisms logP is found to be inferior to 2Xv in the correlation of MIC values. On the basis of regression equations the MIC values of certain ortho substituted phenols are calculated a priori, some of which are corroborated by findings reported in the literature.

Antifungal Agents↗
PubMedDate not supplied

On 3-D graphical representation of DNA primary sequences and their numerical characterization.

In this article we (1) outline the construction of a 3-D "graphical" representation of DNA primary sequences, illustrated on a portion of the human beta globin gene; (2) describe a particular scheme that transforms the above 3-D spatial representation of DNA into a numerical matrix representation; (3) illustrate construction of matrix invariants for DNA sequences; and (4) suggest a data reduction based on statistical analysis of matrix invariants generated for DNA. Each of the four contributions represents a novel development that we hope will facilitate comparative studies of DNA and open new directions for representation and characterization of DNA primary sequences.

Base Sequence↗