Statistical techniques

Statistical techniques

What statistical techniques do QSAR models use? As we have seen in the previous entries, QSAR models allow predicting properties or activities of molecules, and are obtained from the analysis of molecular descriptors with statistical and/ or machine learning techniques. QSAR models can be used qualitatively to classify a substance, for example as a skin irritant or non-irritant. They can also help us to calculate exact numerical values i.e., we may build quantitative models, for example, to calculate how many days it takes for a substance to degrade. As we saw in the entry on computational methods, the first type of models is known as classification models, while the second […]

Molecular descriptors

Molecular descriptors

What are molecular descriptors? In order to generate QSAR models, it is necessary to codify in some way the characteristics of the molecules, in order to have the most detailed possible description of these. In other words, it is necessary to translate the molecular structures into numerical values that can be easily understood by computer algorithms, so that they the most relevant characteristics for the studied bioactivity are selected. These characteristics are what we call ‘molecular descriptors’. But what are these molecular descriptors? Several descriptors have been proposed to date, some with a great deal of complexity, in this post we will attempt to mention the simplest and easiest to […]

QSAR models

QSAR models

QSAR models, what are they and how are they created? The QSAR models, acronym for Quantitative Structure Activity Relationships, are based on one of the most used techniques in the field of chemoinformatics, as we saw in the previous entry. In this post we will help you to understand better how to obtain these models and the different terms employed in reference to these, as well as clear up the most common doubts that they usually cause. What is a QSAR model? QSAR models are complex mathematical algorithms that facilitate and accelerate an important task in fields such as chemistry or drug development: the predictive evaluation of the properties or […]

Computational methods

Computational methods

What computational methods can we use to predict properties of substances? In the previous blog entry, we talked about chemoinformatics within the so-called alternative methods. However, what computational methods can we use to predict a toxicological or physicochemical property of a substance, according to current regulations? How do we decide which one to use? In this post we bring you the answer. There are four methods commonly accepted by the norms such as REACH, regulating the production and import of chemicals in Europe. These four methods are: These computational methods are based on the calculation of molecular descriptors, which can be defined as numeric values quantifying properties calculated from the […]