Introduction and Progress in linear QSAR/QSPR Modeling.

MERCADER, A. G.; DUCHOWICZ, P. R.; FERNÁNDEZ, F. M.; CASTRO, E. A.

Universidad Iberoamericana, Ciudad de Mexico

Taller; 2007 NSF Pan-American Advanced Studies Institute on Sustainability & Green Chemistry; 2007

American Chemical Society Education Division and ACS Green Chemistry Institute

The objective of QSAR (Quantitative Structure Activity Relationships) and QSPR (Quantitative Structure Property Relationships) Theory is to predict properties or biologic activities using the information that arises from the molecular structure. This allows predicting properties and activities still not experimentally measured, even for substances that do not exist because they have not been synthesized yet. [1] The foundations of the theory relies in the fact that the property or activity of a substance is solely determined by it¡¦s molecular structure. However as it can be seen in Fig. 1. the arrow representing the direct link is broken because the relationship remains unknown. Fig. 1. the arrow representing the direct link is broken because the relationship remains unknown. Fig. 1. the arrow representing the direct link is broken because the relationship remains unknown. Fig. 1. the arrow representing the direct link is broken because the relationship remains unknown. it¡¦s molecular structure. However as it can be seen in Fig. 1. the arrow representing the direct link is broken because the relationship remains unknown. Fig. 1. Foundations of QSAR/QSPR Theory In order to reestablish this link we have to go around it. Our usual procedure goes as follows: ƒá A set of substances with measured property or activity is obtained from the literature.A set of substances with measured property or activity is obtained from the literature. ƒá The molecules are divided in two sets, a calibration and a validation set.The molecules are divided in two sets, a calibration and a validation set. ƒá The structures of the compounds are drawn and pre-optimized with a Force Field procedure included in Hyperchem version 6.03 [2], and after that the geometries are further refined by means of a suitable semi empirical method. procedure included in Hyperchem version 6.03 [2], and after that the geometries are further refined by means of a suitable semi empirical method. procedure included in Hyperchem version 6.03 [2], and after that the geometries are further refined by means of a suitable semi empirical method. procedure included in Hyperchem version 6.03 [2], and after that the geometries are further refined by means of a suitable semi empirical method. The structures of the compounds are drawn and pre-optimized with a Force Field procedure included in Hyperchem version 6.03 [2], and after that the geometries are further refined by means of a suitable semi empirical method. ƒá A pool of more than a thousand molecular descriptors is derived involving variables of different types: constitutional, topological, geometrical, charge, etc., using the software e-dragon available online.[3] The relevant aspects of the molecular structure are therefore translated into the molecular descriptors through mathematical formulae obtained from several theories, such as Chemical Graph Theory, Quantum Mechanics, etc. [4,5] of different types: constitutional, topological, geometrical, charge, etc., using the software e-dragon available online.[3] The relevant aspects of the molecular structure are therefore translated into the molecular descriptors through mathematical formulae obtained from several theories, such as Chemical Graph Theory, Quantum Mechanics, etc. [4,5] of different types: constitutional, topological, geometrical, charge, etc., using the software e-dragon available online.[3] The relevant aspects of the molecular structure are therefore translated into the molecular descriptors through mathematical formulae obtained from several theories, such as Chemical Graph Theory, Quantum Mechanics, etc. [4,5] of different types: constitutional, topological, geometrical, charge, etc., using the software e-dragon available online.[3] The relevant aspects of the molecular structure are therefore translated into the molecular descriptors through mathematical formulae obtained from several theories, such as Chemical Graph Theory, Quantum Mechanics, etc. [4,5] A pool of more than a thousand molecular descriptors is derived involving variables of different types: constitutional, topological, geometrical, charge, etc., using the software e-dragon available online.[3] The relevant aspects of the molecular structure are therefore translated into the molecular descriptors through mathematical formulae obtained from several theories, such as Chemical Graph Theory, Quantum Mechanics, etc. [4,5] ƒá Finally we come to the more difficult step in the process, this is finding the best model by selecting those descriptors from the pool which are the most representatives for the property under consideration This will be discussed in the following section model by selecting those descriptors from the pool which are the most representatives for the property under consideration This will be discussed in the following section model by selecting those descriptors from the pool which are the most representatives for the property under consideration This will be discussed in the following section model by selecting those descriptors from the pool which are the most representatives for the property under consideration This will be discussed in the following section Finally we come to the more difficult step in the process, this is finding the best model by selecting those descriptors from the pool which are the most representatives for the property under consideration This will be discussed in the following section