An integrated QSAR-PBK/D modelling approach for predicting detoxification and DNA adduct formation of 18 acyclic food-borne a,ß-unsaturated aldehydes.
Kiwamoto, R. ; Spenkelink, A. ; Rietjens, I.M.C.M. ; Punt, A. - \ 2015
Toxicology and Applied Pharmacology 282 (2015)1. - ISSN 0041-008X - p. 108 - 117.
in-silico model - exocyclic 1,n-2-propanodeoxyguanosine - 1,n(2)-propanodeoxyguanosine adducts - trans-2-hexenal detoxification - glutathione transferases - estragole bioactivation - pharmacokinetic model - carbonyl-compounds - human liver - rat
Acyclic a,ß-unsaturated aldehydes present in food raise a concern because the a,ß-unsaturated aldehyde moiety is considered a structural alert for genotoxicity. However, controversy remains on whether in vivo at realistic dietary exposure DNA adduct formation is significant. The aim of the present study was to develop physiologically based kinetic/dynamic (PBK/D) models to examine dose-dependent detoxification and DNA adduct formation of a group of 18 food-borne acyclic a,ß-unsaturated aldehydes without 2- or 3-alkylation, and with no more than one conjugated double bond. Parameters for the PBK/D models were obtained using quantitative structure-activity relationships (QSARs) defined with a training set of six selected aldehydes. Using the QSARs, PBK/D models for the other 12 aldehydes were defined. Results revealed that DNA adduct formation in the liver increases with decreasing bulkiness of the molecule especially due to less efficient detoxification. 2-Propenal (acrolein) was identified to induce the highest DNA adduct levels. At realistic dietary intake, the predicted DNA adduct levels for all aldehydes were two orders of magnitude lower than endogenous background levels observed in disease free human liver, suggesting that for all 18 aldehydes DNA adduct formation is negligible at the relevant levels of dietary intake. The present study provides a proof of principle for the use of QSAR-based PBK/D modelling to facilitate group evaluations and read-across in risk assessment.
Domino Mukaiyama-Michael reactions in the synthesis of polycyclic systems
Sarabèr, F.C.E. ; Dratch, S. ; Bosselaar, G. ; Jansen, B.J.M. ; Groot, Æ. de - \ 2006
Tetrahedron 62 (2006)8. - ISSN 0040-4020 - p. 1717 - 1725.
silyl enol ethers - catalyzed conjugate addition - vitamin-d-3 northern portion - ring closure reactions - one-pot - acyclic stereoselection - titanium tetrachloride - 2+2+2 construction - carbonyl-compounds - organic-synthesis
Good results were obtained in the Mukaiyama-Michael reaction of the silyl enol ether of cyclohexanone with 2-methyl-2cyclopentenone and carvone, with transfer of the silyl group to the receiving enone and with TrSbCl6 as catalyst. A second Mukaiyama-Michael reaction of this new silyl enol ether with methyl vinyl ketone and cyclization of the resulting adduct leads to tricyclic compounds in one-pot domino sequences. The scope and limitations of this domino reaction have been investigated.