Short-and medium-chain chlorinated paraffins in imported commercial dry cat and dog food in China:Concentrations,distributions and risk assessment

Chlorinated paraffins(CPs)are produced in large amounts and used worldwide.Dietary intake is the primary pathway for the exposure of pets to CPs,but limited information is available concerning the potential contamination of pet food by CPs.In the present study,the concentrations and congener group profiles of short-chain CPs(SCCPs)and medium-chain CPs(MCCPs)were assessed in 35 imported commercial dry cat and dog foods collected in China,and the estimated daily intakes of SCCPs and MCCPs for cats and dogs through the consumption of such foods was calculated.The concentrations of SCCPs and MCCPs in the cat and dog foods were determined to be in the ranges of 108e45,300 ng/g(median:1340 ng/g)and 3.8e52,700 ng/g(median:11 ng/g),respectively.The predominant congener groups were C10Cl6 for SCCPs and C14Cl7-8 for MCCPs.The high levels of CPs found in certain pet foods suggest the potential for adverse health effects.

Construction of on-line supercritical fluid extraction with reverse phase liquid chromatography–tandem mass spectrometry for the determination of capsaicin

A novel on-line system composed of supercritical fluid extraction(SFE), dilution line and reverse phase liquid chromatography/mass spectrometry(RPLC/MS) was constructed for on-line extraction and reverse phase separation of some fat-soluble components in foods. Three columns including a trap column,concentration column and analytical column were used for trapping the fat-soluble components, on-line enrichment and reverse phase separation, respectively. Capsaicinoids were on-line extracted by a CO_2 supercritical fluid, then concentrated and separated by using the C_(18) columns, finally detected by mass spectrometry(MS). Capsaicin eluted at 10.1 min and limit of detection(LOD, S/N=3) for the standard solution is 0.55pg. The linearity was calculated with a value of coefficient of determination(R^2)≥0.998 in the range of 1.1–8.5 ng. Concentrations of capsaicin in the green, yellow, and red bell peppers were determined to be 60.33 ng/g, 31.79 ng/g, 35.38ng/g, respectively.

Profiling the metabolites of astrapterocarpan in rat hepatic 9000g supernatant

Astrapterocarpan(AP) is a bioactive constituent of Astragali Radix and was selected as a model compound for investigating the in vitro metabolism of pterocarpans in this study. Its in vitro metabolism was conducted by incubation with rat hepatic 9000 g supernatant(S9) in the presence of an NADPH-generating system. At first, four compounds were isolated and their structures were elucidated as 6 a-hydroxy-AP(M1), astrametabolin I [M2, 1 a-hydroxy-9, 10-dimethoxy-pterocarp-1(2), 4-diene-3-one], 9-demethyl-AP(M3, nissolin) and 4-methoxy-astraisoflavan(M4, 7, 2’-dihydroxy-4, 3’, 4’-trimethoxy-isoflavan) on the basis of NMR data, respectively. Among them, M1, M2 and M4 were new compounds. Next, the metabolite profile of AP in rat hepatic S9 was obtained via HPLC-DAD-ESI-IT-TOF-MSn, and 40 new metabolites were tentatively identified. These newly identified metabolites included 9 monohydroxylated metabolites, 1 demethylated metabolite, 7 demethylated and monohydroxylated metabolites, 4 dihydroxylated metabolites, 1 hydration metabolite, 1 didemethylated metabolite, 2 glucosylated metabolites, 1 monohydroxylated and dehydrogenated metabolite, 2 monohydroxylated and demethylated and dehydrogenated metabolites, 2 dimerized metabolites, 3 dimerized and monohydroxylated metabolites, 2 dimerized and didemethylated metabolites, and 5 dimerized and demethylated metabolites. Finally, the major metabolic reactions of AP in rat hepatic S9 were summarized and found to be hydroxylation, demethylation, dimerization, hydration, and dehydrogenation. More importantly, the biotransformation from AP to M2 and the dimerization of AP by incubation with hepatic S9 were reported for the first time. In conclusion, this is the first report on the metabolism of a pure pterocarpan in animal tissues, and these findings will provide a solid basis for further studies on the metabolism of other pterocarpans.