QSARs on the Depuration Rate Constants of Polycyclic Aromatic Hydrocarbons in Elliptio complanata

Abstract

Using quantum chemical descriptors and partial least squares (PLS) regression, a quantitative structure -activity relationships (QSARs) model was developed to predict the depuration rate constants (k d ) of polycyclic aromatic hydrocarbons (PAHs) for mussels, Elliptio complanata. With a high cumulative cross-validated regression coefficient value (Q 2 cum ) of 0.927 and low standard deviation (SD) of 0.065, the model obtained by the training set shows a good predictive ability, and it is validated to be robust by predicting the test set. Among 20 quantum chemical descriptors, the dielectric energy (DE), the molecular weight (M w ), and the highest occupied molecular orbital energy (E HOMO ) are the key descriptors governing the logk d values in the model. Increase in the DE or decrease in the M w values leads to the increase in logk d , indicating the van der Waals interactions and steric hindrance effect on the depuration process. Decrease in the E HOMO values results in increasing the logk d values, implying important roles the molecular orbital energies may play in the biological depuration of PAHs in mussels.

QSAR studies on the depuration rates of polycyclic aromatic hydrocarbons, polybrominated diphenyl ethers and polychlorinated biphenyls in mussels (Elliptio complanata)

“…In Table 3, the current QSAR model was compared with four published QSAR models for the depuration rates in mussels (Elliptio complanata) [6,10,11,20]. The first three QSAR models employed the unambiguous statistical algorithm of multivariate linear regression (MLR) and single parameter (log K OW ) to predict the log k d values, which showed comparable performances.…”

“…Moreover, external validation was not mentioned in the three MLR models. Wu et al employed PLS regression and three predictor variables to develop a QSAR model that was simple and reproducible for regulators and non-QSAR experts [6]. However, all the four mentioned QSAR models were constructed on the homologous series of chemicals such as PAHs and PCBs, and the applicability domains were not discussed [6,10,11,20].…”

“…Mussels accumulate POPs very efficiently, and are widely used as bio-indicators in the aquatic environment due to their wide geographical distribution, tolerance to various environmental conditions and availability throughout the year [5]. Mussels can be used to determine the time required to achieve chemical equilibrium, which can be calculated from the depuration rate constants (k d ) of chemicals in organisms [6]. The k d is one of the most important kinetic parameters, which can be used to estimate bioconcentration factors (BCF) and the time to steady state [7][8][9].…”

“…Several QSAR models for the k d of compounds in mussels have been constructed using octanol/water partition coefficients (K OW ) [10,20] or quantum chemical parameters [6,21], which can be used to explore the inherent relations between molecular structures of chemicals and their k d values. Previous studies have constructed QSAR models individually on PAHs [6] or PCBs [10,21], but no QSAR models have been developed on PBDEs or systematically on heterogeneous series of chemicals including PAHs, PCBs and PBDEs.…”

“…Previous studies have constructed QSAR models individually on PAHs [6] or PCBs [10,21], but no QSAR models have been developed on PBDEs or systematically on heterogeneous series of chemicals including PAHs, PCBs and PBDEs. In addition, the molecular structures of the compounds (planar or nonplanar) may make contributions to the k d .…”