6 research outputs found
Chiral Polychlorinated Biphenyls (PCBs) in Bioaccumulation, Maternal Transfer, and Embryo Development of Chicken
Polychlorinated biphenyls (PCBs)
and enantiomer fractions (EFs)
of PCB enantiomers (PCBs 95, 132, 135, and 149) were investigated
in soil and chicken feed, chicken (Gallus domesticus) tissues, eggs on 0, 7, and 14 days after the onset of incubation,
and newborn chick tissues. The EF values of PCBs 95, 132, and 149
changed significantly from soil to chicken tissues, and the values
in the liver exhibited the highest deviation from the racemic ratio,
indicating enantiomer-selective metabolism in hens. Congeners, which
are highly resistant to degradation, such as PCBs 138, 153, and 180,
exhibited the highest maternal transfer potentials when muscle and
liver were used to assess the maternal transfer. However, uniform
transfer ratios were observed for most of the PCB congeners when visceral
fat was used. The EFs of chiral PCBs in eggs either did not match
with muscle or with liver or were similar to those in visceral fat.
These results indicate that hens mainly mobilized visceral fat for
egg formation and PCBs were deposited in eggs by associating with
these lipid materials. Further enantiomeric enrichment of PCBs 95,
132, and 149 occurred in the newborn chick tissues. However, an opposite
enantioselectivity for PCB 135 in newborn chicks was observed. These
results indicate that the potential toxicity of PCB enantiomers to
newborn chicks may be different from that of adults
Using Compound-Specific Stable Carbon Isotope Analysis to Trace Metabolism and Trophic Transfer of PCBs and PBDEs in Fish from an e‑Waste Site, South China
Two fish species (mud carp and northern
snakehead) forming a predator/prey
relationship and sediment samples were collected from a pond contaminated
by e-waste. The concentrations and stable carbon isotope ratios (δ<sup>13</sup>C) of individual polychlorinated biphenyl (PCB) and polybrominated
diphenyl ether (PBDE) congeners were measured to determine if compound-specific
carbon isotope analysis (CSIA) could be used to provide insight into
the metabolism and trophic dynamics of PCBs and PBDEs. Significant
correlations were found in the isotopic data of PCB congeners between
the sediment and the fish species and between the two fish indicating
identical origin of PCBs in sediment and fish. Most PCB congeners
in the fish species were enriched in <sup>13</sup>C compared with
the PCB congeners in the sediments as a result of isotopic fractionation
during the metabolism of PCBs in fish. The isotopic data of several
PCB congeners showing isotopic agreement or isotopic depletion could
be used for source apportionment or to trace the reductive dechlorination
process of PCBs in the environment. The PCB isotopic data covaried
more in the northern snakehead than in the mud carp when compared
to the sediment, implying that a similar isotopic fractionation occurs
from the prey to the predator fish for a PCB congener possibly due
to similar metabolic pathways. The PBDE congener patterns differed
in the three sample types with a high abundance of BDE209, 183, 99,
and 47 in the sediment, BDE47, 153, and 49 in the mud carp and BDE47,
100, and 154 in the northern snakehead. The isotopic change of BDE
congeners, such as BDE47 and BDE49, in two fish species, provides
evidence for biotransformation of PBDEs in biota. The results of this
study suggest that CSIA is a promising tool for deciphering the fate
of PCBs and PBDEs in the environment
Oleiferoside W from the roots of <i>Camellia oleifera</i> C. Abel, inducing cell cycle arrest and apoptosis in A549 cells
<p><i>Camellia oleifera</i> C<i>.</i> Abel has been widely cultivated in China, and a group of bioactive constituents such as triterpeniod saponin have been isolated from <i>C. oleifera</i> C. Abel<i>.</i> In the current study, a new triterpeniod saponin was isolated from the EtOH extract of the roots of <i>C. oleifera</i> C. Abel, named as oleiferoside W, and the cytotoxic properties of oleiferoside W were evaluated in non-small cell lung cancer A549 cells. At the same time the inducing apoptosis, the depolarization of mitochondrial membrane potential (Δψ), the up-regulation of related pro-apoptotic proteins, such as cleaved-PARP, cleaved-caspase-3, and the down-regulation of anti-apoptotic marker Bcl-2/Bax were measured on oleiferoside W. Furthermore, the function, inducing the generation of reactive oxygen species (ROS) and apoptosis, of oleiferoside W could be reversed by N-acetylcysteine (NAC). In conclusion, our findings showed that oleiferoside W induced apoptosis involving mitochondrial pathway and increasing intracellular ROS production in the A549 cells, suggesting that oleiferoside W may have the possibility to be a useful anticancer agent for therapy in lung cancer.</p
Hydrophosphination of Propargylic Alcohols and Amines with Phosphine Boranes
The first uncatalyzed hydrophosphinations of propargylic amines and alcohols with phosphine– borane complexes are described. The reactions proceed at ambient temperature or below without the use of protecting groups or the need to handle pyrophoric secondary phosphines, furnishing air-stable phosphineborane–amines and alcohols in good yields. Utilization of chiral propargylic substrates and unsymmetrical secondary phosphineboranes leads to diastereomeric <i>P</i>-chiral products that can be separated by fractional crystallization or chromatography. Initial applications of these new P–X species to asymmetric catalysis are detailed
An Enantioselective Synthesis of an 11-β-HSD‑1 Inhibitor via an Asymmetric Methallylation Catalyzed by (<i>S</i>)‑3,3′‑F<sub>2</sub>‑BINOL
An
efficient asymmetric synthesis of 11-β-HSD inhibitor <b>1</b> has been accomplished in five linear steps and 53% overall
yield, starting from the readily available 3-chloro-1-phenylpropan-1-one.
The key feature of the synthesis includes an asymmetric methallylation
of 3-chloro-1-phenylpropan-1-one catalyzed by the highly effective
organocatalyst (<i>S</i>)-3,3′-F<sub>2</sub>-BINOL
under solvent-free and metal-free conditions
[2,3]-Sigmatropic Rearrangements of 2‑Phosphineborane 2‑Propen-1-ols: Rapid Access to Enantioenriched Diphosphine Monoxide Derivatives
Hydrophosphination of secondary propargylic alcohols generates phosphine-containing allylic alcohols that undergo facile [2,3]-sigmatropic rearrangements with chlorophosphines, furnishing highly enantioenriched, crystalline diphosphine monoxides. The configuration at the newly formed stereocenter is opposite to that expected based on prior studies, and an ab initio computational evaluation of the possible transition states was performed to help explain the stereochemical course of the reaction