Oxy-PAHs: occurrence in the environment and potential genotoxic/mutagenic risk assessment for human health.

Structurally modified polycyclic aromatic hydrocarbons (PAHs) such as nitrated PAHs (nitro-PAHs) and oxygenated PAHs (oxy-PAHs) can be incriminated in the total toxicity of polycyclic aromatic compounds (PACs) fraction in the environment. Compared to nitro-PAHs, oxy-PAHs have been poorly studied. Oxy-PAHs covers compounds with different moieties such as polycyclic aromatic ketones (PAKs) and polycyclic aromatic quinones (PAQs). In this review, we have compiled exhaustively all the data available on the sources, the fate, and the occurrence of oxy-PAHs focusing on the most ubiquitous ones in the environment, ie PAKs and PAQs. Data concerning their genotoxicity, mutagenicity and tumor promotion potential for humans are also provided based on the mode-of-action analysis framework. Mutagenicity results based on the limited number of oxy-PAHs tested, are unequivocal on the concern they represent. Their omission in mutagenic/carcinogenic risk has caused a dramatic underestimation of cancer risk. On the basis of environmental and genotoxicological data, we suggest prioritized 4 major oxy-PAHs molecules in ecotoxicological and toxicological studies, namely 6 H-benzo[cd]pyren-6-one (BPO), 7,12-benz[a]anthracenequinone (BAQ), 5,12-naphthacenequinone (NCQ) and 11 H-benzo[b]fluoren-11-one (B[b]FO). We also propose to develop biomarkers of exposure and/or risk for these compounds, for example by quantification of DNA adducts.

Synthesis and study of a molecularly imprinted polymer for specific solid-phase extraction of vinflunine and its metabolite from biological fluids.

A molecularly imprinted polymer (MIP) was synthesized in order to specifically extract vinflunine, an anticancer agent, and its metabolite (4-O-deacetylvinflunine) from bovine plasma and artificial urine by solid-phase extraction (SPE). Vinorelbine, a non-fluorinated analogue of vinflunine, was selected as a template for MIP synthesis. The selectivity of MIP versus the template (vinorelbine) and other alkaloids (catharanthine, vinblastine, vincristine, vinflunine and 4-O-deacetylvinflunine) was shown by a SPE protocol carried out with non-aqueous samples. A second protocol was developed for aqueous samples with two consecutive washing steps (AcOH-NH2 OH buffer (pH 7, I=10 mM)-MeOH mixture 95:5 v/v and ACN-AcOH mixture 99:1 v/v) and an elution step (MeOH-AcOH mixture 90:10 v/v). Thus, MIP-SPE of bovine plasma brought high recoveries, 81 and 89% for vinflunine and its metabolite, respectively. This protocol was slightly modified for artificial urine samples in order to obtain a good MIP/NIP selectivity; furthermore, elution recoveries were 73 and 81% for vinflunine and its metabolite, respectively. Repeatability was assessed in both biological matrices and RSD (%) were inferior to 4%. The MIP also showed a suitable linearity (r(2) superior to 0.99), between 0.25 and 10 µg/mL for plasma, and between 1 and 5 µg/mL for artificial urine.

Metabolic expressivity of human genetic variants: NMR metabotyping of MEN1 pathogenic mutants.

Functional consequences of mutations in predisposition genes for familial cancer syndromes remain often elusive, especially when the corresponding gene products play pleiotropic functions and interact with numerous partners. Understanding the consequences of these genetic alterations requires access to their functional effects at the phenotypic level. Nuclear magnetic resonance (NMR) has emerged as a promising functional genomics probe, through its ability to monitor the consequences of genetic variations at the biochemical level. Here, we determine by NMR the metabolic perturbations associated with different disease-related mutations in the MEN1 gene, responsible for the multiple endocrine neoplasia syndrome, type 1 (MEN1), an example of hereditary cancer. The MEN1 gene encodes the Menin protein. Based on a cellular model that allows exogenous overexpression of either the wild type (WT) Menin protein or disease-related variant forms, we evaluate the feasibility of using metabolic profiles to discriminate cells with WT versus variant Menin overexpression. High-resolution magic angle spinning (HRMAS) NMR of whole cells allows to determine the metabolic features associated with overexpression of WT Menin as compared to the one of six different missense variants observed in MEN1 patients. We then identify several statistically significant individual metabolites associated with the metabolic signature of pathogenic versus WT variants. Whether such a metabolic phenotyping approach using cell lines could be exploited as a functional test in a human genetic cancer syndrome is further discussed.

High-resolution magic angle spinning description of the interaction states and their kinetics among basic solutes and functionalized silica materials.

Modeling of the interaction is crucial to understanding and predicting chromatography. However, the complexity and variety of the grafted motifs render the creation of an accurate model overwhelmingly challenging, so that most often the classification of column separation properties is described by monitoring the retention times of carefully selected control molecules. We analyzed here the characteristics of the interplay of compounds of basic nature by (1)H HRMAS NMR, which provide relevant descriptors for products with pharmaceutical properties, with chromatographic phases for Reversed Phase Liquid Chromatography. Eight grafted silica phases were selected, differing to enhance specific structural properties (monomeric and polymeric grafts, endcapping or not, carbon content, alkyl with polar embedded group or alkyl bonded chain, chemical nature of end capping, native silica). These materials were put in interaction with five basic molecules, previously chosen as probes for the evaluation of efficient base deactivated liquid stationary phases using five theoretical molecular descriptors to cover a large scale of molecular volume, polar surface area, LogP, hydrogen-bond donor capacity and finally hydrogen-bond acceptor capacity. (1)H HRMAS NMR was capable of describing qualitatively a wealth of interaction states, characterized both thermodynamically and kinetically. In one case (penbutolol) up to five interaction states could be differentiated. Variable temperature experiments revealed the complexity of the retention process on grafted silica as in some cases the kinetics of the interaction is shown to slow down on increasing the temperature.

Chromatographic-nuclear magnetic resonance can provide a prediction of high-pressure liquid chromatography shape selectivity tests.

NMR diffusometry has been recently demonstrated as a means of investigating the mobility variations of solutes induced by chromatographic phases (under the acronym chromatographic-NMR). Particularly, a given compound has its average diffusivity reduced proportionally to its affinity towards the solid. In this work we propose the first comparison of chromatographic-NMR and tests for assessment of column performance, to investigate to what measure the novel approach could provide an assay of the outcome of a given stationary phase without the need of packing the relative column. Specifically, using bulk materials, we reproduce with very good agreement a shape selectivity test as reported in the catalog of a column producer, consisting of four probe molecules, applied to two different stationary phases.