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Ultraviolet absorption characteristics and calculated semi-empirical parameters as chemical descriptors in multivariate modelling of polychlorinated biphenyls
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
1996 (English)In: Journal of Chemometrics, ISSN 0886-9383, E-ISSN 1099-128X, Vol. 10, no 2, 171-185 p.Article in journal (Refereed) Published
Abstract [en]

The structural variation within the polychlorinated biphenyls (PCBs) was characterized by using principal component analysis (PCA). A multivariate model was evolved from 52 physicochemical descriptors including measured ultraviolet (UV) absorption spectra, calculated semiempirical parameters (AM1) and properties captured from the literature. Parameters calculated by using the AM1-Hamiltonian were e.g. heat of formation, dipole moments, ionization potential and the barrier of internal rotation. The UV spectra were measured and digitized in the range 200-300 nm. The multivariate model revealed that most of the information within the set of physicochemical parameters was related to molecular size. Descriptors depending on size were e.g. GC retention times, partition coefficients and a subset of semiempirically derived energy terms. Important also were parameters reflecting differences in substitution patterns and related to electronic and steric properties, such as UV absorption in the wavelength region 245-300 nm, the barrier of internal rotation and the ionization potential. The developed model describes the large variation in physicochemical characteristics within the PCBs. The importance of a broad chemical characterization is illustrated by a quantitative structure-activity relationship (QSAR) for the potency of inhibition of intercellular communication for 27 structurally diverse tetra- to heptachlorinated PCBs.

Place, publisher, year, edition, pages
1996. Vol. 10, no 2, 171-185 p.
Keyword [en]
PCBs, UV, AM1 calculations, muitivariate modelling, PCA, QSARs
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:umu:diva-3296DOI: 10.1002/(SICI)1099-128X(199603)10:2<171::AID-CEM416>3.0.CO;2-UISI: A1996TZ90300009OAI: oai:DiVA.org:umu-3296DiVA: diva2:141848
Available from: 2000-05-26 Created: 2000-05-26 Last updated: 2014-08-29Bibliographically approved
In thesis
1. Physico-chemical characteristics and quantitative structure-activity relationships of PCBs
Open this publication in new window or tab >>Physico-chemical characteristics and quantitative structure-activity relationships of PCBs
2000 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The polychlorinated biphenyls (PCBs) comprise a group of 209 congeners varying in the number of chlorine atoms and substitution patterns. These compounds tend to be biomagnified in foodwebs and have been shown to induce an array of effects in exposed organisms. The structural characteristics of the PCBs influence their potency as well as mechanism of action. In order to assess the biological potency of these compounds a multi-step quantitative structure-activity relationship (QSAR) procedure was used in the project described in this thesis.

The ultraviolet absorption (UV) spectra were measured for all 209 PCBs, and digitised for use as physico-chemical descriptors. Interpretations of the spectra using principal component analysis (PCA) showed the number of ortho chlorine atoms and para-para substitution patterns to be significant. Additional physico-chemical descriptors were derived from semi-empirical calculations. These included various molecular energies, the ionisation potential, electron affinity, dipole moments, and the internal barrier of rotation. The internal barrier of rotation was especially useful for describing the conformation of the PCBs on a continuous scale.

In total 52 physico-chemical descriptors were compiled and analysed by PCA for the tetra- to hepta-chlorinated congeners. The structural variation within these compounds was condensed into four principal properties derived from a PCA for use as design variables in a statistical design to select congeners representative for these homologue-groups. The 20 selected PCBs have been applied to study structure-specific biochemical responses in a number of bioassays, and to study the biomagnification of the PCBs in various fish species.

QSARs were established using partial least squares projections to latent structures (PLS) for the PCBs potency to inhibit intercellular communication, activate respiratory burst, inhibit dopamine uptake in synaptic vesicles, compete with estradiol for binding to estrogen receptors, and induce cytochrome P4501A (CYP1A) related activities. By the systematic use of the designed set of PCBs the biological potency was screened over the chemical domain of the class of compounds. Further, sub-regions of highly potent PCBs were identified for each response measured. For risk assessment of the PCBs potency to induce dioxin-like activities the predicted induction potencies (PIPs) were calculated. In addition, two sets of PCBs were presented that specifically represent congeners of environmental relevance in combination with predicted potency to induce estrogenic and CYP1A related activities.

Place, publisher, year, edition, pages
Umeå: Kemi, 2000. 70 p.
Keyword
polychlorinated biphenyls, PCBs, physico-chemical properties, statistical design, multivariate, PCA, PLS, biomagnification, BMF, bioassay, CYP1A, SAR, QSAR, REPs, risk assessment, Chemistry, Kemi
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-17 (URN)91-7191-838-8 (ISBN)
Public defence
2000-05-26
Opponent
Available from: 2000-05-26 Created: 2000-05-26Bibliographically approved

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