Correlations, biology

Rogers, J. A. Choi, Y. W., The liposome partitioning system for correlating biological activities for imidazolidine derivatives, Pharm. Res. 10, 913-917 (1993). 

The existence of isomeric polycyclic aromatic diol epoxide compounds provides rich opportunities for attempting to correlate biological activities with the physico-chemical reaction mechanisms, and conformational and biochemical properties of the covalent DNA adduct8 which are formed. 

Hansch equation A Hansch equation is a linear free-energy relationship that correlates biological activity (log 1/C) to molecular and substituent parameters. The parameters describe properties such as sterics, lipophilicity, and electronic effects, and the coefficients on the parameters determine the relative importance of each parameter. 

These can be broadly divided into those that apply to sections of the molecule and those that involve the whole molecule. The former include parameters such as van der Waals radii, Charton s steric constants and the Verloop steric parameters. The latter range from relative molecular mass (RMM) and molar volumes to surface area. They have all been used to correlate biological activity to structure with varying degrees of success. 

Hansch et al. (9, 10) have developed linear free energy relations which can correlate biological activity and chemical structure. Equations 1 and 2, together with simplified versions, have been proposed to relate the molar concentration, Cx, of a substituted compound of a series, which all cause an equivalent biological response, to the hydrophobic bonding or partition constant, r, and the Hammett constant, [Pg.137]

Hansch analysis tries to correlate biological activity with physico-chemical properties by linear and nonlinear regression analysis, finding property-activity relationship models. 

The attempt to correlate biological activity with chemical structure in quantitative terms assumes that a functional dependence exists between the observed biological response and certain physicochemical properties of molecules. Without a mechanistic model one obtains it by an empirical correlation. A rational way to define such empirical relationships is within the extrathermo-dynamic approach (1). Although extrathermodynamic relationships... 

Hansch analysis tries to correlate biological activity with physico-chemical properties by linear and nonlinear regression analysis, finding property-activity relationship models. A Craig plot is a plot of two substituent parameters (e.g., Hansch-Fujita n and Hammett a values). The simplest Hansch analysis is based on the Hansch linear model [Kubinyi, 1988b], defined... 

In conclusion, the following summarizes possible correlative biological markers of early carbon disulfide poisoning (1) electromyographical indications of neural lesions (2) decreased neuromuscular conduction... 

In the early time of QSAR studies, often meaningless combinations of quantum chemical parameters were used to correlate biological data. The proper application of such parameters is, for example, illustrated by Eq. (51), which describes the mutagenic... 

As a way to solve both of these problems in using Es to correlate biological properties, Verloop and co-workers expanded the approach of using the 3D structure of the substituent. This is implemented in the STERIMOL computer program. They originally calculated five characteristic steric properties of a substituent from the van der Waals surface of the molecules. For this they used the atomic and bond properties that are used to construct the CPK physical models that were popular at the time. Later they decided that three descriptors were sufficient ... 

McKinney, J.D., Toxicology of Selected Symmetrical Hexachlorobiphenyls. Correlating Biological Effects with Chemical Structure. Proceedings of the National Conference on PCB s, Chicago, Illinois, November, 1975. In EPA Publication-560/6-75-004, pp. 73-76. 

Parameters which encode certain structural features and properties are needed to correlate biological activities with chemical structures in a quantitative manner. Of special value are physicochemical properties which are directly related to the intermolecular forces involved in the drug-receptor interaction as well as to the transport and distribution properties of drugs. In this respect hydrophobic, polar, electronic, and steric properties are most important most often, polarizability parameters are considered as being closely related to steric parameters and are discussed together with these parameters, although they are definitely different (if structural variation is appropriate). 

The concept of pharmacophore identification based on molecular electrostatic potentials has been reviewed [908]. Some other approaches to correlate biological activities with the interactions at certain positions of the binding site were discussed in chapter 2 (eqs. 17 and 18). 

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