QSAR Quantitative Structure and

Apart from finding structures that give energy minima, most molecular mechanics packages will calculate structural features such as the surface area or the molecular volume. Quantities such as these are often used to investigate relationships between molecular structure and pharmacological activity. This field of human endeavour is called QSAR (quantitative structure and activity relations). 

QCISD(T) 207, 208 QCPE (Quantum Chemistry Program Exchange) 173 QM/MM model 262 QSAR (Quantitative Structure and Activity Relations) 56 QST (Quadratic Synchronous Transit)... 

Besides the aforementioned descriptors, grid-based methods are frequently used in the field of QSAR quantitative structure-activity relationships) [50]. A molecule is placed in a box and for an orthogonal grid of points the interaction energy values between this molecule and another small molecule, such as water, are calculated. The grid map thus obtained characterizes the molecular shape, charge distribution, and hydrophobicity. 

PW91 (Perdew, Wang 1991) a gradient corrected DFT method QCI (quadratic conhguration interaction) a correlated ah initio method QMC (quantum Monte Carlo) an explicitly correlated ah initio method QM/MM a technique in which orbital-based calculations and molecular mechanics calculations are combined into one calculation QSAR (quantitative structure-activity relationship) a technique for computing chemical properties, particularly as applied to biological activity QSPR (quantitative structure-property relationship) a technique for computing chemical properties... 

The QSAR (quantitative structure-activity relationship) approach has been considered for the identification of toxicants that bind to steroid and aryl... 

QSARs (quantitative structure-activity relationships) Relationships between structural parameters of chemicals and their toxicity. 

Bis(oxazohnes) figands have been so widely used for the Diels-Alder reaction between N-2-alkenoyl-l,3-oxazolidine-2-one and cyclopentadiene that Lipkowitz and Pradhan developed a QSAR (quantitative structure-activity relationship) using Comparative Molecular Field Analysis (CoMFA) for a set of 23 copper-catalysts containing mainly bis(oxazoline) figands. The generated... 

ADMET absorption, distribution, metabolism, excretion and toxicity BLW-ED block-localized wave function energy decomposition hERG human ether-a-go-go-related gene QSAR quantitative structure-activity relationship... 

Odor and taste quality can be mapped by multidimensional scaling (MDS) techniques. Physicochemical parameters can be related to these maps by a variety of mathematical methods including multiple regression, canonical correlation, and partial least squares. These approaches to studying QSAR (quantitative structure-activity relationships) in the chemical senses, along with procedures developed by the pharmaceutical industry, may ultimately be useful in designing flavor compounds by computer. 

It is not yet possible to design a molecule with specific odor (or taste) characteristics because the relations between sensory properties of flavor compounds and their molecular properties are not well understood. As a consequence, the development of compounds with desired flavor qualities has had to rely on relatively tedious synthetic approaches. Recent advances, however, in computer-based methods developed by the pharmaceutical industry to study QSAR (quantitative structure-activity relationships) may ultimately be helpful in the rational design of new flavor-structures with predictable sensory attributes. Results from QSAR studies may also provide insight into the mechanism of the molecule-receptor interaction. 

For years, we have been studying QSAR (quantitative structure-activity relationship) analyses of pesticides and other bioactive compounds. In many examples, we have found a decisive role of the steric effect in determining the activity variation. In this chapter, applications of various steric constants such as E E°, Vw and STERIMOL parameters to QSAR studies mostly from our own laboratory are reviewed. 

Quantitative Structure—Activity Relationships (QSAR). Quantitative Structure—Activity Relationships (QSAR) is the name given to a broad spectmm of modeling methods which attempt to relate the biological activities of molecules to specific structural features, and do so in a quantitative manner (see Enzyme inhibitors). The method has been extensively applied. The concepts involved in QSAR studies and a brief overview of the... 

Quantitative Structure and Activity Relationship (QSAR) Models and... 

Attempts to quantitatively relate chemical structure to biological action were first initiated in the 19th century, but it was not until the 1960s that Hansch and Fujita devised a method that successfully incorporated quantitative measurements into SAR determinations (see section 4.4). The technique is referred to as QSAR (quantitative structure-activity relationships). One of its most successful uses has been in the development in the 1970s of the antiulcer agents cimetidine and ranitidine. Both SARs and QSARs are important parts of the foundations of medicinal chemistry. 

J. L. Fauchere, QSAR Quantitative Structure-Activity Relationships in Drug Design. Proceedings of the 7th European Symposium on QSAR held in Interlaken, Switzerland, September 5-9, 1988, in Progress in Clinical and Biological Research, Vol. 291, Alan R. Liss, New York, 1989. 

QSAR Quantitative structure-activity relationship. Quantitative structure-bio-logical activity model derived using regression analysis and containing as parameters physical-chemical constants, indicator variables, or theoretically calculated values. 

The epoch of QSAR (Quantitative Structure-Activity Relationships) studies began in 1963-1964 with two seminal approaches the a-p-7i analysis of Hansch and Fujita " and the Free-Wilson method. The former approach involves three types of descriptors related to electronic, steric and hydrophobic characteristics of substituents, whereas the latter considers the substituents themselves as descriptors. Both approaches are confined to strictly congeneric series of compounds. The Free Wilson method additionally requires all types of substituents to be suflficiently present in the training set. A combination of these two approaches has led to QSAR models involving indicator variables, which indicate the presence of some structural fragments in molecules. 

L. H. Hall, B. Mohney and L. B. Kier, The electrotopological state-an atom index for QSAR., Quantitative Structure-Activity Relationships, 1991, 10, 43-51. 

QSAR. Quantitative structure-activity relationships—the science of deriving quantitative linear or nonlinear mathematical relationships between physicochemical and topo-logical/topographical properties of chemical structures and their biological activity. Originally, regression analysis was the only tool used to derive QSAR equations. More re-... 

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