Chemical Descriptors
Descriptors, as a science, began
evolving with the advent of QSAR in drug design studies. Very early on,
it was discovered that the steric, electronic, hydrophobic properties
of molecules were largely responsible for their drug action. So, simple
global molecular properties like logP (capturing hydrophobicity),
Solubility, Ionisation constant etc were used as descriptors in
classical QSAR. Later on, new descriptors were added either to address
a specific problem or as a means of encrypting the structural
information in a better manner and at different levels of depth. Today,
there are more than 3000 descriptors covering 1D, 2D, 3D, 4D, quantum
chemical, fingerprint-based, field-based, surface area related,
chirality related, etc.
The following definition is an attempt
to describe descriptors - "a chemical descriptor is the final result of
a logical and mathematical procedure which transforms chemical
information encoded within a symbolic representation of a molecule into
an useful number or the result of some standardized experiment."
Apart from the obvious use in QSAR,
descriptors also find use in compound profiling and mining. A
relatively less known filed is Reverse QSAR, practised mostly by
medicinal chemists. Here, QSAR model interpretation leads forward to an
understanding of how to modify chemical structure to possibly influence
the property studied. ‘DMCS’ ("Descriptors to Mask
Chemical Information") is another recent innovation. This is driven by
the need for more data while not revealing confidential information on
structures.
See Also:
Similarity
Principle, Fingerprint-based
Similarity.
References:
1. "Descriptor collision and confusion: Toward
the design of descriptors to mask chemical structures",
Cristian Bologaa, Tharun Kumar Allua, Marius Olaha, Michael A. Kapplerb
& Tudor I. Oprea, Journal of Computer-Aided Molecular Design
(2005) 19:625-635.
2. Roberto Todeschini and Viviana Consonni,
‘Handbook of molecular descriptors’, Wiley-VCH, pp
667, 2000.
Cite This As:
Sumathy K,"Chemical Descriptors" From
QSARWorld - A Strand Life Sciences Web Resource.
http://www.qsarworld.com/insilico-chemistry-chemical-descriptors.php
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