Bifenthrin Research Articles

The Effect of Different Medium on Enantioselectivity in Degradation of Bifenthrin.

Bifenthrin (BF) is a chiral pesticide with two enantiomers. In this work, its stereoselective degradation was investigated in plants and domesticated active sludge. Considering that the degradation to pesticides of plants was effected by external conditions, hence, nanometer materials (gothite) were added into soil to explore the effect of sorption on enantioselectivity in degradation of BF. The microbial community that was responsible for BF-biodegrading in active sludge was studied by polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE). In plant researches, chiral difference was discovered in the degradation of pesticides that onions resulted in. The existence of gothite in soil not only reduced the amount of BF that plants uptake from the environment, but it also enlarged the chiral difference during the process, indicating that the absorption of gothite to pesticides had enantioselectivity, which may be generated by that adsorption site where BF combined with gothite located in the chiral center of the pesticide. In studies of sludge, BF can be effectively degraded and decline of both isomers followed first-order kinetics. However, there was no obvious stereoselective degradation in domesticated sludge. The analysis of DGGE revealed that active sludge maintained the rich microbial community in the whole process (H > 3). The H index increased in the early domestication, which may because BF had no direct toxicity to the bacteria. The bacteria were able to degrade the small dose of the pesticide and absorbed it as nutrition. The sequence results demonstrated that the variety of bacteria grew, instead of Acidobacteria, Betaproteobacteria, Sphingobacteriia and Alphaproteobacteria, Flavobacteria also appearing in sludge after domestication.

Cis-bifenthrin induces immunotoxicity in adolescent male C57BL/6 mice.

Bifenthrin (BF) is an important synthetic pyrethroid. Previous studies have demonstrated that cis-BF exhibits toxic effects on development, the neurological, reproductive and endocrine system. In this study, we evaluated the immunotoxicity caused by cis-BF in adolescent male C57BL/6 mice. Mice were exposed orally to 0, 5, 10, and 20 mg/kg/d for 3 weeks. The results showed that body weight, spleen weight, and splenic cellularity decreased in mice exposed to 20 mg/kg/d cis-BF. Additionally, we found that the mRNA levels of the pro-inflammatory factors IL-1β, IL-6, CXCL-1, and TNF-α, in peritoneal macrophages, the spleen, and the thymus were inhibited in the cis-BF-treated groups. Moreover, MTT assays demonstrated that cis-BF inhibited splenocyte proliferation stimulated by LPS or Con A, as well as the secretion of IFN-γ on Con A stimulation. Collectively, the results of this study suggest that exposure to cis-BF has the potential to induce immunotoxicity in adolescent male C57BL/6 mice.

Exposure to bifenthrin disrupts the development of testis in male Sebastiscus marmoratus

Bifenthrin (BF) is a pyrethroid insecticide that is widely used in agriculture, horticulture, and for residential purposes. However, few studies addressing the reproductive toxicity of BF on fishes are available. The present study was conducted to investigate the effects of BF on testicular development in Sebastiscus marmoratus and to gain insight into its mechanism. After exposure to 1, 10 and 100 ng/L BF for 50 days, there was a reduced number of mature sperm and an abundance of the late stages of spermatocysts in the testes. The levels of 17β-estradiol and testosterone were decreased significantly after BF exposure. The activity of caspase-3 was increased in a dosedependent manner after BF exposure, TUNEL assay indicated that BF exposure resulted in the occurrence of apoptosis in the testes, which might be main reason for the inhibition of spermatogenesis.

Thermal and other analytical studies on bifenthrin urea co-inclusion complex

In current study, thermal and other analytical techniques have been successfully utilized in characterization of bifenthrin urea co-inclusion complex (BNUCIC)—a human-guarded insecticide formulation. Bifenthrin (BN)—a widely used pyrethroid insecticide was successfully engulfed in the cavities of hexagonal urea lattice in the presence of a suitable rapidly complexing agent (RCA). Resulting formulation shields human beings from insecticides through direct inhalation, ingestion or dermal contact. Insects will be exposed to insecticide only after BNUCIC comes in contact with water in soil/crops following switching on of water sprinkling/distribution system in the fields. Formation of BNUCIC was characterized by DSC, FTIR, XRD and 1H-NMR studies. Thermal analysis played a key role in characterization, in estimation of the minimum proportion of RCA needed for complexation and to study the influence of relative proportion of RCA on heat of decomposition of complexes. Thermal analysis depicted gradual increase in heat of decomposition of BNUCIC and excellent r2 value with increasing molar fraction of linear chain RCA. Increased heat of decomposition ensures improved physical stability of complexes. Overlay of DSC curves of BNUCIC complexes revealed absence of melting endotherm of insecticide indicating amorphous nature of BN. FTIR spectrum and XRD diffractogram depicted characteristic peaks and interplanar spacings of hexagonal urea. 1H-NMR spectrum revealed presence of exposed protons of guest moieties in hexagonal urea. BNUCIC exhibited uniform formulation composition and improved dissolution profile. Studies reveal insecticide–fertilizer amalgamation to be a useful technique for formulation of an effective human-guarded insecticide formulation with improved characteristics.

Cis-bifenthrin causes immunotoxicity in murine macrophages

Synthetic pyrethroids (SPs) are commonly used insecticides that have been detected in mammals, including humans, indicating a potential threat to human health. Bifenthrin (BF), as well as other pyrethroids, has been shown to possess neurotoxic, reproductive, hepatotoxic and nephrotoxic potential in mammals. However, studies regarding the immunotoxicity of BF and its mechanism are limited. In this study, we aim to exam the immunotoxicity of cis-BF on the murine macrophage cell line, RAW 264.7. MTT assay results demonstrated that cis-BF exposure induced apoptosis in RAW 264.7 cells in a concentration-dependent manner. We found that the expression of p53 and caspase-3 was up-regulated, while the expression of Bcl-2 was down-regulated during cis-BF-induced apoptosis. In addition, we also found that cis-BF exposure caused oxidative stress in RAW 264.7 cells in a dose-dependent manner. Interestingly, cis-BF exposure was found to inhibit the increase in transcription levels of IL-1β, IL-6 and TNF-α responding to LPS stimulation. We also found that the induced increase in IFN-β mRNA levels upon Sendai virus infection was blocked with cis-BF exposure. Finally, we found that cis-BF exposure increased ROS levels and dysregulated mRNA levels of oxidative stress-related genes in RAW 264.7 cells. The present study elucidates the immunotoxicity effect of cis-BF on macrophages and its possible underlying mechanism. The results from this study support the necessity to evaluate immune dysfunction in the risk assessment of cis-BF exposure.

From the Cover: Vulnerability of C6 Astrocytoma Cells After Single-Compound and Joint Exposure to Type I and Type II Pyrethroid Insecticides.

A primary mode-of-action of all pyrethroid insecticides (PYRs) is the disruption of the voltage-gated sodium channel electrophysiology in neurons of target pests and nontarget species. The neurological actions of PYRs on non-neuronal cells of the nervous system remain poorly investigated. In the present work, we used C6 astrocytoma cells to study PYR actions (0.1-50 μM) under the hypothesis that glial cells may be targeted by and vulnerable to PYRs. To this end, we characterized the effects of bifenthrin (BF), tefluthrin (TF), α-cypermethrin (α-CYP), and deltamethrin (DM) on the integrity of nuclear, mitochondrial, and lysosomal compartments. In general, 24- to 48-h exposures produced concentration-related impairment of cell viability. In single-compound, 24-h exposure experiments, effective concentration (EC)15s 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT assay) were computed as follows (in μM): BF, 16.1; TF, 37.3; α-CYP, 7.8; DM, 5.0. We found concentration-related damage in several C6-cell subcellular compartments (mitochondria, nuclei, and lysosomes) at ≥ 10-1 μM levels. Last, we examined a mixture of all PYRs (ie, Σ individual EC15) using MTT assays and subcellular analyses. Our findings indicate that C6 cells are responsive to nM levels of PYRs, suggesting that astroglial susceptibility may contribute to the low-dose neurological effects caused by these insecticides. This research further suggests that C6 cells may provide relevant information as a screening platform for pesticide mixtures targeting nervous system cells by expected and unexpected toxicogenic pathways potentially contributing to clinical neurotoxicity.

Selective separation of bifenthrin by pH-sensitive/magnetic molecularly imprinted polymers prepared by pickering emulsion polymerization

Via Pickering emulsion polymerization, pH-sensitive magnetic molecularly imprinted polymers (HM-MIPs) were synthesized using bifenthrin (BF) as the template molecule, and pH-sensitive monomer methacrylic acid as the functional monomer. Characterizations of HM-MIPs were achieved by FTIR, TGA, TEM, SEM, and VSM, and the results indicated that HM-MIPs exhibited magnetic property (Ms=1.06 emu/g). HM-MIPs were acted as the adsorbent for a series of adsorption performance testing of BF. Equilibrium data were described by the Langmuir and Freundlich isotherm models. Kinetic properties were successfully investigated by pseudo-first-order model, pseudo-second-order model. The selective recognition experiments exhibited outstanding selectively adsorption effect of the HM-MIPs for target BF over diethyl phthalate and fenvalerate. In water, the HM-MIPs could achieve the adsorption and release of BF by controlling the pH value of the aqueous solution. The results indicated that the molecularly imprinted polymers exhibited good adsorption, selectivity and pH-sensitive performance for BF.

Acute exposure to synthetic pyrethroids causes bioconcentration and disruption of the hypothalamus–pituitary–thyroid axis in zebrafish embryos

Synthetic pyrethroids (SPs) have the potential to disrupt the thyroid endocrine system in mammals; however, little is known of the effects of SPs and underlying mechanisms in fish. In the current study, embryonic zebrafish were exposed to various concentrations (1, 3 and 10μg/L) of bifenthrin (BF) or λ-cyhalothrin (λ-CH) until 72h post fertilization, and body condition, bioaccumulation, thyroid hormone levels and transcription of related genes along the hypothalamus–pituitary–thyroid (HPT) axis examined. Body weight was significantly decreased in the λ-CH exposure groups, but not the BF exposure groups. BF and λ-CH markedly accumulated in the larvae, with concentrations ranging from 90.7 to 596.8ng/g. In both exposure groups, alterations were observed in thyroxine (T4) and triiodothyronine (T3) levels. In addition, the majority of the HPT axis-related genes examined, including CRH, TSHβ, TTR, UGT1ab, Pax8, Dio2 and TRα, were significantly upregulated in the presence of BF. Compared to BF, λ-CH induced different transcriptional regulation patterns of the tested genes, in particular, significant stimulation of TTR, Pax8, Dio2 and TRα levels along with concomitant downregulation of Dio1. Molecular docking analyses revealed that at the atomic level, BF binds to thyroid hormone receptor (TRα) protein more potently than λ-CH, consequently affecting HPT axis signal transduction. In vitro and in silico experiments disclosed that during the early stages of zebrafish development, BF and λ-CH have the potential to disrupt thyroid endocrine system.

Thermosensitive/magnetic molecularly imprinted polymers prepared by Pickering emulsion polymerization for selective separation of bifenthrin

Thermosensitive/magnetic molecularly imprinted polymers (TM-MIPs) were prepared by Pickering emulsion polymerization. With this method, SiO2 nanoparticles were used as the Pickering emulsion stabilizer, N-isopropylacrylamide functioned as the thermosensitive monomer participating in co-polymerization, and bifenthrin (BF) acted as the template molecule. The results of the characterizations demonstrated that the TM-MIPs were porous and magnetic inorganic/polymer composite microparticles with magnetic sensitivity (Ms = 0.7921 emu g−1), thermal stability (below 473 K), and magnetic stability (over the pH range of 2.0–8.0). TM-MIPs were used as sorbents to remove bifenthrin (BF), and then were swiftly split in magnetic field. The Freundlich isotherm model preferably matched with the experimental data. The adsorption kinetic of the TM-MIPs was primely fitted by the pseudo-second-order, indicating that the chemical reaction could be the rate-limiting step in the process of BF absorption. The selective recognition experiments exhibited that the TM-MIPs have obvious effect on selective adsorption of BF with diethyl phthalate and fenvalerate. In aqueous solutions, the adsorption of BF onto the TM-MIPs had response to temperature, and could be used for adsorbing and separating bifenthrin.

Neurodevelopmental consequences of gestational and lactational exposure to pyrethroids in rats.

Indiscriminate use of pyrethroids has raised serious health related concerns, especially about their effects on children. The present study was designed to assess the developmental neurotoxicity of two pyrethroids; bifenthrin (BIF) and β-cyfluthrin (CYF) administered at 1/15 of LD50 in rats. Pregnant females were exposed to the test compounds orally throughout gestation and lactation periods. Neonates were weighed and sexed at birth and were observed for any gross abnormality. Growth, viability and weaning indices were calculated during the lactation period. Exposure to both the compounds did not alter the physical developmental parameters viz. eye opening, pinna detachment, and fur appearance. CYF significantly impaired growth and survivability of pups. Behavioral endpoints assessed in neonates (surface righting, pivoting, and negative geotaxis reflex) as well as adults (motor activity and motor coordination) exhibited marked effect of CYF treatment. Administration of BIF to pregnant dams impaired pivoting in neonates. Decreased locomotion in the open-field and impaired rota-rod performance were also witnessed in BIF-exposed animals. Enhanced oxidative stress was seen in corpus striatum, cerebellum, and hippocampus regions of the brain; reduced catalase, superoxide dismutase, and glutathione peroxidase activities were measured in BIF and CYF treated weanlings. Acetylcholinesterase activity was also found to be lowered following administration of both compounds at PND 21. The present results suggest that exposure to pyrethroids during critical periods of growth can induce long term effects on the behavior of animals. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1761-1770, 2016.

Evidence for effects on thermoregulation after acute oral exposure to type I and type II pyrethroids in infant rats

Most pyrethroid (PYR) insecticides may be classified either as type-I compounds, which produce whole body tremors and hyperthermia, or type-II compounds, which produce salivation, choreoathetosis, and hypothermia (i.e., producing T and CS neurobehavioral syndromes, respectively). This classification is based on clinical observations in adult rats and mice after intracerebroventricular or intravascular administration of highly effective acute (bolus) doses. PYR neurotoxicity in infant animals is not characterized as much as in adult animals. Endpoints informing on vital determinants of mammal's maturation, such as body temperature may help recognizing age-related differences in susceptibility to PYRs. In this work, body temperature (Tb) was monitored at 30-min intervals after acute oral exposure to T-syndrome PYR bifenthrin (BIF), CS-syndrome PYR cypermethrin (CYPM), and a BIF–CYPM mixture in weanling rats by using a subcutaneous temperature monitoring system. In both single-compound assays, a time- and dose-related decline of Tb was the most evident impact on thermoregulation observed starting at ~2–3h after dosing. Moreover, 15–18mg/kg BIF induced a mild increase in Tb before the hypothermic action was apparent. The lowest effective dose for temperature perturbation was 15mg/kg for BIF and 10mg/kg for CYPM, and moderate neurobehavioral alterations were evident at 12 and 10mg/kg, respectively. When low effective doses of BIF and CYPM were co-administered mild behavioral effects and a transient increase in Tb (p=0.02) were observed at 1–2h, and no Tb decline was apparent afterwards compared to control animals. Noteworthy, the hypothermic action of BIF in infant rats was quite different from the hyperthermia consistently reported in studies using mature animals. Our results suggest that body temperature monitoring may be useful as a complementary assessment to reveal qualitative age-specific pesticide effects in rats.

Well-designed multihollow magnetic imprinted microspheres based on cellulose nanocrystals (CNCs) stabilized Pickering double emulsion polymerization for selective adsorption of bifenthrin

In our study, the multihollow magnetic imprinted microspheres (HM-IMs) were synthesized by Pickering double water in oil in water (w1/o/w2) emulsion polymerization. In w1/o/w2 emulsion, hydrophobic Fe3O4 nanoparticles were used to stabilize the inner water in oil (w1/o) droplets. Cellulose nanocrystals (CNCs), which were acquired from cotton source by acid hydrolysis process, were used as stabilizer on the outer oil in water (o/w2) interface. The template bifenthrin (BF) and functional monomer were contained in oil phase. The imprinting process was conducted by thermally initiated radical polymerization of functional and cross-linked monomers. The multihollow structure was well-designed by adjusting amounts of stabilizers and degree of emulsification. Characterization results indicated that the Pickering double w1/o/w2 emulsion and HM-IMs were successfully produced. The as-prepared sorbents possessed thermal stability (below 250°C) and enough magnetic sensitivity (Ms=0.46emug−1). The sorbents were used to selectively adsorb template BF. The adsorption equilibrium was fitted well by Langmuir isothermal model, indicating the monolayer molecular adsorption for BF. And pseudo-second-order kinetics model gave a better fit to the kinetic data, suggesting that the chemical process could be the rate-limiting step in the adsorption of BF. The selective recognition capability for template BF of HM-IMs sorbents was proved to be excellent compared with structural analogs. And the HM-IMs presented good dynamic adsorption performance for BF and the fixed bed adsorption conditions were tunable. The regeneration ability of the sorbents was also proved to be satisfying by five repeated adsorption–desorption cycles.

Enantioselective apoptosis induced by individual isomers of bifenthrin in Hep G2 cells

Bifenthrin (BF) has been used in racemate for agricultural purposes against soil insects, leading to increased inputs into soil environments. However, most of the studies about the toxicology research on BF were performed in its racemic form. The aim of the present study was to evaluate the enantiomer-specific cis-BF-induced apoptosis and intracellular reactive oxygen species (ROS) generation on human hepatocarcinoma cells (Hep G2). The results of cell viability assay and cytoflow assay indicated an obvious enantioselective hepatocyte toxicity of 1S-cis-BF in Hep G2 cells. 1S-cis-BF also induced ROS production, up-regulated Bax protein expression and down-regulated Bcl-2 expression levels. The present study suggested that enantioselective toxicity should be evaluated on currently used chiral pesticides, such as synthetic pyrethroids.

Multilevel evaluations of potential liver injury of bifenthrin

The widespread use of pesticides, such as pyrethroids, increases health risks to non-target organisms. The potential toxicity of pyrethroids to the liver remains unclear and could be easily overlooked if only the common clinical indicators of liver disease are examined. In the present study, BALB/c mice were given intraperitoneal injections of 0, 2, 4, or 8 mg/kg bifenthrin (BF) for 7 days. The potential liver injury of BF and its underlying mechanism were then investigated through multilevel evaluations. Histological analyses and serum enzyme activities showed no obvious clinical evidence of liver damage. Oxidative stress was induced and caspases were activated in response to increased BF concentrations. Exposure to BF also significantly altered the expression levels of mitochondrial apoptosis-related genes in dose-dependent relationships. The microarray results showed that BF could disturb the metabolic profile and extensively induce genes related to oxidative stress, including the cytochrome P450 family, glutathione peroxidases, glutathione s-transferases and kinases. In the in vivo model, BF induced liver injury through caspase-mediated mitochondrial-dependent cell death, a process that is closely related to oxidative stress, even in the absence of classical clinical biomarkers of liver dysfunction. The results of this study suggest that classical evaluations are not adequate for liver toxicity of pyrethroids, and highlight the need for more comprehensive assessment of health risks of these widely used pesticides.

Effects of potassium chloride and potassium sulphate on the efficacy of insecticides against infestation by Helopeltis theivora (Heteroptera: Miridae) in tea plantations

Helopeltis theivora Waterhouse is a major sucking pest of tea in northeast India. No effective predators or parasitoids have been recorded from the field, and, therefore, insecticides play a significant role in the control of this pest. Potassium is known to impart physiological resistance to plants against sucking pests. The present study conducted two field trials to evaluate the bioefficacy of thiamethoxam 25 WG and bifenthrin 8 SC applied alone at the dosage recommended by the Tocklai Tea Research Institute and in combination with 2% potassium chloride (KCl) and mined potassium sulphate (K2SO4) against H. theivora. No phytotoxic effects were observed in the field when tea bushes were sprayed. The control of H. theivora achieved by the combinations of thiamethoxam + KCl/K2SO4 and bifenthrin + KCl/K2SO4 was found to be statistically significant (P < 0.05) compared with the sole application of the insecticides. These treatments could be included in the current integrated pest management programme against H. theivora.

Disruption of the hormonal network and the enantioselectivity of bifenthrin in trophoblast: maternal-fetal health risk of chiral pesticides.

Endocrine-disrupting chemicals (EDCs) can interfere with normal hormone signaling to increase health risks to the maternal-fetal system, yet few studies have been conducted on the currently used chiral EDCs. This work tested the hypothesis that pyrethroids could enantioselectively interfere with trophoblast cells. Cell viability, hormone secretion, and steroidogenesis gene expression of a widely used pyrethroid, bifenthrin (BF), were evaluated in vitro, and the interactions of BF enantiomers with estrogen receptor (ER) were predicted. At low or noncytotoxic concentrations, both progesterone and human chorionic gonadotropin secretion were induced. The expression levels of progesterone receptor and human leukocyte antigen G genes were significantly stimulated. The key regulators of the hormonal cascade, GnRH type-I and its receptor, were both upregulated. The expression levels of selected steroidogenic genes were also significantly altered. Moreover, a consistent enantioselective interference of hormone signaling was observed, and S-BF had greater effects than R-BF. Using molecular docking, the enantioselective endocrine disruption of BF was predicted to be partially due to enantiospecific ER binding affinity. Thus, BF could act through ER to enantioselectively disturb the hormonal network in trophoblast cells. These converging results suggest that the currently used chiral pesticides are of significant concern with respect to maternal-fetal health.

Dynamics of uptake and elimination of pyrethroid insecticides in zebrafish (Danio rerio) eleutheroembryos

Synthetic pyrethroids (SPs) are among the most heavily used insecticides for residential and agricultural applications. Their residues have frequently been detected in aquatic ecosystems. Despite their high aquatic toxicity, their toxicokinetics are still unclear. In this study, the kinetics of uptake and depuration of three SPs, permethrin (PM), bifenthrin (BF) and λ-cyhalothrin (λ-CH), were determined for the first time using zebrafish eleutheroembryo assays. The diastereoisomer selectivity of PM in eleutheroembryos was further examined. The results indicated that three SPs were quickly taken up by eleutheroembryos. The bioaccumulation factors of the SPs ranged from 125.4 to 708.4. The depuration of SPs in zebrafish eleutheroembryos followed the first-order process. The elimination rate constants (k2) of SPs in eleutheroembryos ranged from 0.018 h-1 to 0.0533 h-1. The half-lives (t1/2) were in the range 13.0–38.5h. The diastereoisomer fraction (DF) values for PM in the eleutheroembryos estimated at different uptake and depuration times were all significantly greater than the original value (DF=0.43), indicating selective enrichment and elimination of cis-PM relative to trans-PM. These results reveal a high capacity for SP bioconcentration by zebrafish eleutheroembryos, suggesting that SPs possess a highly cumulative risk to fish.

ISOLATION AND CHARACTERIZATION OF BIFENTHRIN CATABOLIZING BACTERIAL STRAIN &lt;i&gt;BACILLUS CIBI&lt;/i&gt; FROM SOIL FOR PYRETHROIDS BIODEGRADATION

Pyrethroids are commonly used in most parts of the world and are reported to have potential health ris ks. Bifenthrin, a third generation pyrethroid used as i nsecticide has caused potential effect on aquatic l ife and human health. Bioremediation is a practical approac h to reduce pesticide in the environment and report s of microbial degradation of bifenthrin are meagre. This study was aimed at isolating and characterizin g bacterial isolates for the efficient removal of bif enthrin residues in the environment. A bacterial st rain PGS-4 isolated from sewage of pesticide industry wa s tested for growth at higher concentration of bifenthrin (800 mg L -1 ) and the optimum pH and temperature were determined. The strain utilized bifenthrin as sole carbon source for growth over a wide range of pH (4.0-9.0) and temperatures (1637°C). On the basis of growth kinetics studies, the optimal conditions were determined to be pH 7.0-8. 0 and 30°C. 16S rRNA gene sequence analysis showed that strain PGS-4 forms a distinct phylogenetic lineage within the evolutionary radiation encompass ed by the genus Bacillus and showed 99% similarity to that of Bacillus cibi. This study depicts the ability of B. cibi to utilize bifenthrin at higher concentration under in vitro thereby can be used in eliminating bifenthrin from contaminated soils as a practical approach to reduce pyrethroid toxicity in the environment.

Enantioselective disruption of the endocrine system by Cis‐Bifenthrin in the male mice

Bifenthrin (BF), as a chiral pyrethroid, is widely used to control field and household pests in China. At present, the commercial BF is a mixed compound containing cis isomers (cis-BF) including two enantiomers of 1R-cis-BF and 1S-cis-BF. In the present study, the two individual cis-BF enantiomers were separated by a preparative supercritical fluid chromatography. Then, four week-old adolescent male ICR mice were orally administered 1R-cis-BF and 1S-cis-BF separately daily for 3 weeks at doses of 0, 7.5 and 15 mg/kg/day, respectively. Results showed that the transcription status of some genes involved in cholesterol synthesis and transport as well as testosterone (T) synthesis in the testes were influenced by cis-BF enantiomers. Especially, we observed that the transcription status of key genes on the pathway of T synthesis including cytochrome P450 cholesterol side-chain cleavage enzyme (P450scc) and cytochrome P450 17α-hydroxysteroid dehydrogenase (P45017α)) were selectively altered in the testis of mice when treated with 1S-cis-BF, suggesting that it is the possible reason to explain why the lower serum T concentration in 1S-cis-BF treated group. Taken together, it concluded that both of the cis-BF enantiomers have the endocrine disruption activities, while 1S-cis-BF was higher than 1R-cis-BF in mice when exposed during the puberty. The data was helpful to understand the toxicity of cis-BF in mammals under enantiomeric level.

Rapid determination of pyrethroids in tomatoes using gas chromatography combined with dispersive liquid-liquid microextraction

An analytical method was established for the determination of three pyrethroids (bifenthrin, fenpropathrin and flucythrinate) in tomatoes using the quick, easy, cheap, effective, rugged and safe (QuEChERS) cleanup and gas chromatography. The tomato samples were extracted with acetonitrile, cleaned-up by dispersive solid-phase extraction using primary secondary amine as sorbents, concentrated by dispersive liquid-liquid microextraction (DLLME), and analyzed by gas chromatography. Factors affecting the extraction efficiency such as the type and volume of extraction solvent and the volume of dispersive and extraction time were investigated in detail. In the DLLME procedure, 40 microL chloroform was used as the extraction solvent and 1 000 microL acetonitrile was used as the dispersive solvent and the extraction time was 60 s. Under the optimized conditions, the limits of detection for bifenthrin, fenpropathrin and flucythrinate were 0.5, 0.5 and 0.3 microg/kg, and the average recoveries in tomato samples at the spiked levels of 1, 10 and 50 microg/kg were 89% - 109%, 92.5% - 105% and 90% - 108% with the relative standard deviations of 2.5% - 7.6%, 2.8% - 5.7% and 3.8% - 9.1%, respectively. The proposed method is simple, quick, safe, reliable and applicable to analyze pyrethroid residues in tomato samples.