Dynamic residual pattern of azoxystrobin in Swiss chard with contribution to safety evaluation.

This study aimed at quantifying the residual amount of azoxystrobin in Swiss chard samples grown under greenhouse conditions at two different locations (Gwangju and Naju, Republic of Korea). Samples were extracted with acetonitrile, separated by salting out, and subjected to purification by using solid-phase extraction. The analyte was identified using liquid chromatography-ultraviolet detection. The linearity of the calibration range was excellent with coefficient of determination 1.00. Recovery at three different spiking levels (0.1, 0.5, and 4 mg/kg) ranged between 82.89 and 109.46% with relative standard deviation <3. The limit of quantification, 0.01 mg/kg, was considerably much lower than the maximum residue limit (50 mg/kg) set by the Korean Ministry of Food and Drug Safety. The developed methodology was successfully used for field-treated leaves, which were collected randomly at 0-14 days following azoxystrobin application. The rate of disappearance in/on Swiss chard was ascribed to first-order kinetics with a half-life of 8 and 5 days, in leaves grown in Gwangju and Naju greenhouses, respectively. Risk assessments revealed that the acceptable daily intake percentage is substantially below the risk level of consumption at day 0 (in both areas), thus encouraging its safe consumption.

A quick and effective methodology for analyzing dinotefuran and its highly polar metabolites in plum using liquid chromatography-tandem mass spectrometry.

A simple and effective method was developed for analyzing dinotefuran and its three metabolites (MNG, UF, and DN) in plum using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Due to the polarity and high water miscibility, dinotefuran and some of its metabolites (especially DN) have some limitations to be extracted with acetonitrile and salt following the "QuEChERS" sample preparation methodology. Alternatively, the samples were extracted with methanol, and purified with dispersive-solid phase extraction procedure (d-SPE) using primary secondary amine (PSA) and C18 sorbents after filtration, and mass up. Due to the suppression effect originated from plum matrix, matrix-matched calibration curves, which provided good linearity with coefficient of determination (R2)≥0.998, were used for quantification of all analytes. Blank plum samples fortified with 2 spiking levels (10×LOQ and 50×LOQ) yielded satisfactory recoveries for all tested analytes in the range of 83.01 to 110.18% with relative standard deviation (RSD)≤8.91. The method was successfully applied to field-incurred plum samples and dinotefuran and all metabolites were positively detected and quantified. In conclusion, we suggest that the method can be expanded to polar compounds having solvent and partitioning problems in any of the versions of QuEChERS.

Dissipation kinetics, pre-harvest residue limits, and dietary risk assessment of the systemic fungicide metalaxyl in Swiss chard grown under greenhouse conditions.

The residual behavior of the systemic fungicide, metalaxyl, in Swiss chard cultivated at two different locations under greenhouse conditions was investigated using high-performance liquid chromatography coupled with an ultraviolet detector (HPLC-UVD). Samples were randomly collected over 14 days and extracted using acetonitrile, partitioned using solid sodium chloride, and a solid-phase extraction (SPE) NH2 cartridge was used for cleanup. The linearity over a concentration range 0.05-50 mg/L was excellent with a coefficient of determination (R2) of 0.9997. The recovery rate ranged from 77.05 to 88.92% with relative standard deviations (RSDs) ≤ 10.74, and the limits of detection (LOD) and quantification (LOQ) were 0.0033 and 0.01 mg/kg, respectively. The initial (2 h after application) deposits were 4.69 and 5.90 mg/kg for sites 1 and 2, respectively, which increased to 4.95 and 6.57 mg/kg, respectively, one day post-application, owing to the systemic properties of the fungicide. The dissipation half-life was 5.3 and 6.0 days for sites 1 and 2, respectively. The pre-harvest residue limit (PHRL) suggested that if 55.38 and 47.23 mg/kg was applied 10 days before harvest or 33.28 and 30.73 mg/kg was applied 5 days before harvest (for sites 1 and 2, respectively) then the concentration will fall below the maximum residue limit (MRL = 20.0 mg/kg) at the time of harvest. The dietary risk assessment, estimated as hazard quotient (RQ%), indicate that metalaxyl can be safely used in/on Swiss chard, with no hazardous effects expected for consumers.

Residual dynamic and risk assessment of dimethomorph in Swiss chard grown at two different sites.

Residue analysis of dimethomorph in Swiss chard cultivated at two different locations under greenhouse conditions was conducted using high-performance liquid chromatography-ultraviolet detection and confirmed by tandem mass spectrometry. The randomly collected samples (over 14 days) were extracted with acetonitrile and purified using a Florisil solid-phase extraction cartridge. Linearity over a concentration range of 0.05-50.0 mg/L had an excellent coefficient of determination of 0.9996. Recovery rate ranged from 82.98 to 95.43% with relative standard deviations ≤5.12% and limits of detection and quantification of 0.003 and 0.01 mg/kg, respectively. The initial deposits [day 0 (2 h post-application)] were considerably lower (7.57 and 8.55 mg/kg for sites 1 and 2, respectively) than the maximum residue limit (30 mg/kg) set by the Korean Ministry of Food and Drug Safety. The dissipation half-life was approximately the same, being 5.0 and 5.1 days for sites 1 and 2, respectively. Risk assessment estimated as acceptable daily intake revealed a value of 0.084 or 0.094% (day 0) and 0.014% (10 days post-application), for sites 1 and 2, respectively. The values indicated that dimethomorph can be safely used on Swiss chard, with no hazardous effects expected for Korean consumers.

LC-MS/MS characterization, anti-inflammatory effects and antioxidant activities of polyphenols from different tissues of Korean Petasites japonicus (Meowi).

The Korean Petasites japonicus is a perennial plant used in folk medicine as a remedy for many diseases and popularly consumed as spring greens. Ten polyphenols were characterized from the leaves, stems and roots of this plant via high-performance liquid chromatography-tandem mass spectrometry. Individual polyphenols were quantified for the first time using calibration curves of six structurally related external standards. Validation data indicated that coefficients of determinations (R2 ) were ≥0.9702 for all standards. Recoveries measured at 50 and 100 mg/L were 80.0-91.9 and 80.3-105.3%, respectively. Precisions at these two concentration levels were 0.7-6.1 and 1.1-5.5%, respectively. The total number of identified components was largest for the leaves and smallest for the stems. The leaf and root polyphenolic extracts showed anti-inflammatory effects by inducing LPS-activated COX-2 and iNOS protein levels in mouse macrophage RAW 264.7 cells. The antioxidant capacity of the polyphenols, when evaluated for DPPH (α,α-diphenyl-ß-picrylhydrazyl)ˑ , ABTS+ [2-2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] and superoxide radical scavenging activities, and in ferric reducing ability of plasma (FRAP) assays, was highest in the leaf and lowest in the stem. This trend suggests that the antioxidant capacities depend primarily on polyphenol concentration in each tissue. The current findings suggest that polyphenols derived from P. japonicas tissues could have potential as functional health foods.

Flavone polyphenols dominate in Thymus schimperi Ronniger: LC-ESI-MS/MS characterization and study of anti-proliferative effects of plant extract on AGS and HepG2 cancer cells.

Thymus schimperi is a highly localized and a rare plant endemic to Ethiopia. An optimized and validated high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method was applied to characterize 23 polyphenolic compounds found in ethyl acetate extracts of the plant. From those, flavones dominated and luteolin was the major component contributing 21.83% of the total composition (or 46.05±0.59g/kg of fresh sample weight). Validation data showed a determination coefficient (R2)≥0.997. Limits of detection (LOD) and quantification (LOQ) were 0.03-0.97 and 0.11-3.23mg/L, while recovery values spiked at 5 and 50mg/L were between 70.89-115.39 and 67.65-120.19%, respectively. Except for caffeic acid and epicatechin gallate, the relative standard deviations (%RSDs) were far below 15%, showing acceptable precision values. The plant extracts inhibited cell proliferation and induced cell death in human gastric adenocarcinoma (AGS) and liver hepatocellular carcinoma (HepG2) cancer cells. This is the first report of polyphenolic components from T. schimperi being characterized using HPLC-ESI-MS/MS. Being components of many edible vegetables, fruits, and spices, the identified polyphenols suggest that T. schimperi could be a potential food with promising health benefits.

A Dalbergia odorifera extract improves the survival of endotoxemia model mice by inhibiting HMGB1 release.

BACKGROUND: Dalbergia odorifera T. Chen (Leguminosae) is an indigenous medicinal herb that is widely used as a popular remedy in northern and eastern Asia. However, the cellular mechanisms underlying the biological activity of D. odorifera are not fully elucidated. METHODS: Anti-inflammatory effect of D. odorifera extract (DOE) was determined through intraperitoneal injection in a mouse model of endotoxemia induced by lipopolysaccharide (LPS). RAW 264.7 cells, a murine macrophage, were also treated with LPS to generate a cellular model of inflammation, and investigated the anti-inflammatory activity and underlying mechanisms of DOE and its constituent isoliquiritigenin. RESULTS: DOE dose-dependently inhibited LPS-induced release of high mobility group box 1 (HMGB1), a late proinflammatory cytokine, and decreased cytosolic translocation of HMGB1 in RAW264.7 cells. This inhibitory effect of DOE on HMGB1 release was observed in cells treated with DOE before or after LPS treatment, suggesting that DOE is effective for both treatment and prevention. In addition, DOE significantly inhibited LPS-induced formation of nitric oxide (NO) and expression of inducible NO synthase (iNOS) in a dose-dependent manner. These effects of DOE were accompanied by suppression of HMGB1 release triggered by LPS, suggesting a possible mechanism by which DOE modulates HMGB1 release through NO signaling. Isoriquiritigenin, a constituent of DOE, also attenuated LPS-triggered NO formation and HMGB1 release in RAW264.7 cells, indicating that isoriquiritigenin is an indexing molecule for the anti-inflammatory properties of DOE. Furthermore, c-Jun N-terminal kinase, but not extracellular signal-regulated kinase and p38, mediated DOE-dependent inhibition of HMGB1 release and NO/iNOS induction in RAW 264.7 cells exposed to LPS. Notably, administration of DOE ameliorated survival rates in a mouse model of endotoxemia induced by LPS, where decreased level of circulating HMGB1 was observed. CONCLUSION: These results suggest that DOE confers resistance to LPS-triggered inflammation through NO-mediated inhibitory effects on HMGB1 release.

Application of a solvent-free solid injection technique coupled with GC-MS for discrimination between the secondary metabolites of wild and cultivated South Korean medicinal foods.

Solvent-free solid injection was applied to differentiate between wild and cultivated South Korean medicinal foods, including dureup (Aralia elata), deodeok (Codonopsis lanceolata) and doraji (Platycodon grandiflorus). A number of compounds were identified in wild and cultivated dureup (53 and 46), deodeok (47 and 51) and doraji (43 and 38). Secondary metabolites, including butanal,2-methyl-, ß-caryophyllene, neoclovene, α-humulene, γ-curcumene, ß-bisabolene, and phytol, were identified in dureup with significantly (P < 0.05) different amounts between both types. In deodeok, squalene and other main components such as acetic acid, methyl ester, furan-methyl-furfural, 2-furan-methanol, and 5-methyl-furfural, were statistically different between the two types. Doraji has significantly different compounds such as furfural, 5-methyl-furfural, 2-methoxy-phenol, 2-methoxy-4-(1-propenyl)-phenol, and 1-(4-hydroxy-3-methoxyphenyl)-2-propanone. Although we failed to confirm the key compounds, a new compound, namely desaspidinol, was synthesized for the first time and its retention index determined under the experimental conditions. This solventless, easy technique can be used as a simple way to discriminate between wild and cultivated types of medicinal plants via identification of volatile markers or specific fingerprints.

Residual determination and risk assessment of buprofezin in plum (Prunus domestica) grown in open-field conditions following the application of three different formulations.

This study was conducted to characterize the residual level and perform a risk assessment on buprofezin formulated as an emulsifiable concentrate, wettable powder, and suspension concentrate over various treatment schedules in plum (Prunus domestica). The samples were extracted with an AOAC quick, easy, cheap, effective, rugged, and safe, 'QuEChERS', method after major modifications. As intrinsic interferences were observed in blank plum samples following dispersive-solid phase extraction (consisting of primary secondary amine and C18 sorbents), amino cartridges were used for solid-phase extraction. Analysis was carried out using liquid chromatography with diode array detection and confirmed by liquid chromatography-tandem mass spectrometry. The method showed excellent linearity with determination coefficient (R2 = 1) and satisfactory recoveries (at two spiking levels, 0.5 and 2.5 mg/kg) between 90.98 and 94.74% with relative standard deviation (RSD) ≤8%. The limit of quantification (0.05 mg/kg) was considerably lower than the maximum residue limit (2 mg/kg) set by the Codex Alimentarius. Absolute residue levels for emulsifiable concentrates were highest, perhaps owing to the dilution rate and adjuvant. Notably, all formulation residues were lower than the maximum residue limit, and safety data proved that the fruits are safe for consumers. Copyright © 2016 John Wiley & Sons, Ltd.

Impaired Inactivation of L-Type Ca2+ Current as a Potential Mechanism for Variable Arrhythmogenic Liability of HERG K+ Channel Blocking Drugs.

The proarrhythmic effects of new drugs have been assessed by measuring rapidly activating delayed-rectifier K+ current (IKr) antagonist potency. However, recent data suggest that even drugs thought to be highly specific IKr blockers can be arrhythmogenic via a separate, time-dependent pathway such as late Na+ current augmentation. Here, we report a mechanism for a quinolone antibiotic, sparfloxacin-induced action potential duration (APD) prolongation that involves increase in late L-type Ca2+ current (ICaL) caused by a decrease in Ca2+-dependent inactivation (CDI). Acute exposure to sparfloxacin, an IKr blocker with prolongation of QT interval and torsades de pointes (TdP) produced a significant APD prolongation in rat ventricular myocytes, which lack IKr due to E4031 pretreatment. Sparfloxacin reduced peak ICaL but increased late ICaL by slowing its inactivation. In contrast, ketoconazole, an IKr blocker without prolongation of QT interval and TdP produced reduction of both peak and late ICaL, suggesting the role of increased late ICaL in arrhythmogenic effect. Further analysis showed that sparfloxacin reduced CDI. Consistently, replacement of extracellular Ca2+ with Ba2+ abolished the sparfloxacin effects on ICaL. In addition, sparfloxacin modulated ICaL in a use-dependent manner. Cardiomyocytes from adult mouse, which is lack of native IKr, demonstrated similar increase in late ICaL and afterdepolarizations. The present findings show that sparfloxacin can prolong APD by augmenting late ICaL. Thus, drugs that cause delayed ICaL inactivation and IKr blockage may have more adverse effects than those that selectively block IKr. This mechanism may explain the reason for discrepancies between clinically reported proarrhythmic effects and IKr antagonist potencies.

Polyphenolic profile and antioxidant effects of various parts of Artemisia annua L.

An annual Korean weed, Artemisia annua L., has been used as a folk medicine for the treatment of a number of diseases. Remarkably, among the 32 polyphenols characterized in various parts of plant tissue, including flowers, leafs, stems and roots, 10 compounds were detected for the first time using liquid chromatography-tandem mass spectrometry (LC/MS/MS). The quantification method was validated using structurally related external standards with determination coefficients (R(2) ) ≥0.9995. The limits of detection and quantitation were 0.068-3.932 and 0.226-13.108 mg/L, respectively. The recoveries estimated at 50 and 100 mg/L ranged between 60.6-92.2 and 61.3-111%, respectively, with relative standard deviations <12%. The roots contained the largest concentration of identified components, while the flowers contained the least. The antioxidant capacity evaluated in terms of 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation-scavenging activities and reducing power was highest in the roots and lowest in the flowers. The findings are well correlated and suggest that the antioxidant capacities principally depend upon the polyphenol concentrations in each part of the plant.

The polyphenolic profiles and antioxidant effects of Agastache rugosa Kuntze (Banga) flower, leaf, stem and root.

Agastache rugosa Kuntze (Korean mint) is used as a spice and in folk medicine in East Asia. The present study identified a total of 18 polyphenols from the flower, leaf, stem and roots of this plant using high-performance liquid chromatography-tandem mass spectrometry. Fourteen of these compounds had not previously been identified in these plant tissues. Each polyphenol was validated in comparison with external calibration curves constructed using structurally related compounds, with determination coefficients >0.9993. The limits of detection and quantification were 0.092-0.650 and 0.307-2.167 mg/L, respectively. Recoveries of 61.92-116.44% were observed at two spiking levels, with 0.91-11% precision, expressed as relative standard deviation (except anthraquinone spiked at 10 mg/L). Hydroxycinnamic acid was the most abundant compound in the root, while the flowers showed the highest total flavonoid level. Antioxidant activities, determined in terms of reducing power, Fe(2+) chelating activity and the radical scavenging activities using α,α-diphenyl-ß-picrylhydrazyl and 2-2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid, increased in a concentration-dependent manner; the highest activity was identified in the stems, followed by leaves > flowers > roots. These findings indicate that A. rugosa is a good source of bioactive compounds and can be used as a functional food.

Preparation of a Monoclonal Antibody against Gintonin and Its Use in an Enzyme Immunoassay.

Gintonin is a novel ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand. Gintonin elicits an [Ca(2+)]i transient in animal cells via activation of LPA receptors. In vitro studies have shown that gintonin regulates various calcium-dependent ion channels and receptors. In in vivo studies, gintonin elicits anti-Alzheimer's disease activity through the activation of the non-amyloidogenic pathway and anti-metastatic effects through the inhibition of autotaxin. However, a method for gintonin quantitation in ginseng has not been developed. In the present study, we developed an enzyme immunoassay (EIA) to measure gintonin. A monoclonal antibody was raised in a mouse using gintonin as the immunogen, and an indirect competitive EIA was used to measure gintonin. The working range was 0.01-10 µg per assay. The anti-gintonin monoclonal antibody did not cross-react with the ginsenosides Ra, Rb1, Rb2, Rc, Rd, Re, Rf, Rg1, and Rg3 or with LPAs such as LPA C16:0, LPA C18:0, LPA C18:1, and LPA C18:2. Using a standard curve, we measured the amount of gintonin in various ginseng extract fractions. Interestingly, we only detected a little amount of gintonin in conventional hot water extracts of Korean red ginseng. However, we can measure gintonin after ethanol extraction of Korean red ginseng marc. Thus, gintonin can be extracted from ginseng with ethanol but not water, and the remaining Korean red ginseng marc can be used to obtain gintonin. These results indicate that the EIA with the anti-gintonin monoclonal antibody can be used to quantify gintonin in various ginseng preparations, including commercial ginseng products.

Dietary-flavonoid-rich flowers of Rumex nervosus Vahl: Liquid chromatography with electrospray ionization tandem mass spectrometry profiling and in vitro anti-inflammatory effects.

Rumex nervosus is a plant species found widely in Eastern Africa and the Arabian Peninsula. In addition to its uses in traditional medicinal, the plant shows various biological activities, such as antiviral, antibacterial, and antioxidant activity. In this study, nine flavonols, six flavones, three flavanones, and one flavanol were characterized from the flowers of R. nervosus using liquid chromatography with electrospray ionization tandem mass spectrometry and literature data. Validation data indicated that the determination coefficients (R(2) ) were ≥ 0.9914. The limits of detection and quantification were in the ranges of 0.15-1.24 and 0.50-4.13 mg/L, respectively. Recoveries at 10 and 50 mg/L were 71.1-110.2 and 65.4-115.1%, with relative standard deviations of 7.4-40.1 and 2.1-13.0%, respectively. Quercetin 3-O-rhamnoside (10) was the dominant component, contributing 30.8% of total flavonoids (1003.0 ± 26.2 mg/kg fresh flower sample), whereas luteolin 6-C-glucoside (3) was the lowest yielding compound (0.1%). The 19 flavonoids identified were characterized for the first time. In vitro anti-inflammatory studies showed that this mixture can suppress the production of inflammatory mediators, including inducible nitric oxide synthase, cyclooxygenase-2, kappa B inhibitor, and interleukin-1ß, by down-regulating the nuclear factor-kappa B and mitogen-activated protein kinases pathways. The results of this study may provide information for processing R. nervosus as a potential source of functional food.

Oral toxicity of isotretinoin, misoprostol, methotrexate, mifepristone and levonorgestrel as pregnancy category X medications in female mice.

An oral toxicity study of several pregnancy category X drugs was performed in female ICR mice. The drugs were administered orally once daily for 3 days at doses of 1, 10 and 100 µg/kg for isotretinoin; 6.7, 67 and 670 µg/kg for misoprostol; 83, 830 and 8,300 µg/kg for methotrexate; 3.3, 33 and 330 µg/kg for mifepristone; and 25, 250 and 2,500 µg/kg for levonorgestrel. During the test period, clinical signs, mortality, body weight, hematology, serum biochemistry and necropsy findings were examined. Following administration of methotrexate at 8,300 µg/kg, a number of animals exhibited decreased spontaneous activity, and one animal died. In the hematological analysis, compared with those treated with the control, the animals treated with the drugs exhibited similar significant decreases in the number of granulocytes and granulocyte differentiation, and increases in lymphocyte differentiation. In the serum biochemical analysis, animals receiving high doses of the five drugs demonstrated significant changes in uric acid, glucose, alkaline phosphatase, total bilirubin, lipase, total cholesterol and calcium. At necropsy, intestinal redness was frequently observed in animals that received the high dose of methotrexate. Uterus enlargement and ovary dropsy were also detected in the groups receiving mifepristone and levonorgestrel. Despite the short-term exposure, these drugs exhibited significant side effects, including white blood cell toxicity, in the mouse model. Category X drugs can be traded illegally via the internet for the purpose of early pregnancy termination. Thus, illegal abuse of the drugs should be further discouraged to protect mothers.

Gintonin, a novel ginseng-derived lysophosphatidic acid receptor ligand, stimulates neurotransmitter release.

Gintonin is a novel ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand. Gintonin elicits an intracellular calcium concentration [Ca(2+)]i transient via activation of LPA receptors and regulates calcium-dependent ion channels and receptors. [Ca(2+)]i elevation by neurotransmitters or depolarization is usually coupled to neurotransmitter release in neuronal cells. Little is known about whether gintonin-mediated [Ca(2+)]i transients are also coupled to neurotransmitter release. The PC12 cell line is derived from a pheochromocytoma of the rat adrenal medulla and is widely used as a model for catecholamine release. In the present study, we examined the effects of gintonin on dopamine release in PC12 cells. Application of gintonin to PC12 cells induced [Ca(2+)]i transients in concentration-dependent and reversible manners. However, ginsenoside Rg3, another active ingredient of ginseng, induced a lagged and irreversible [Ca(2+)]i increase. The induction of gintonin-mediated [Ca(2+)]i transients was attenuated or blocked by the LPA1/3 receptor antagonist Ki16425, a phospholipase C inhibitor, an inositol 1,4,5-triphosphate receptor antagonist, and an intracellular Ca(2+) chelator. Repeated treatment with gintonin induced homologous desensitization of [Ca(2+)]i transients. Gintonin treatment in PC12 cells increased the release of dopamine in a concentration-dependent manner. Intraperitoneal administration of gintonin to mice also increased serum dopamine concentrations. The present study shows that gintonin-mediated [Ca(2+)]i transients are coupled to dopamine release via LPA receptor activation. Finally, gintonin-mediated [Ca(2+)]i transients and dopamine release via LPA receptor activation might explain one mechanism of gintonin-mediated inter-neuronal modulation in the nervous system.

Dynamic behaviour and residual pattern of thiamethoxam and its metabolite clothianidin in Swiss chard using liquid chromatography-tandem mass spectrometry.

A simultaneous method was developed to analyse thiamethoxam and its metabolite clothianidin in Swiss chard using tandem mass spectrometry (in the positive electrospray ionisation mode using multiple reaction monitoring mode) to estimate the dissipation pattern and the pre-harvest residue limit (PHRL). Thiamethoxam (10%, WG) was sprayed on Swiss chard grown in two different areas under greenhouse conditions at the recommended dose rate of 10 g/20 L water. Samples were collected randomly up to 14 days post-application, extracted using quick, easy, cheap, effective, rugged, safe (QuEChERS) acetate-buffered method and purified via a dispersive solid phase extraction (d-SPE) procedure. Matrix matched calibration showed good linearity with determination coefficients (R(2)) ⩾ 0.998. The limits of detection (LOD) and quantification (LOQ) were 0.007 and 0.02 mg/kg. The method was validated in triplicate at two different spiked concentration levels. Good recoveries (n=3) of 87.48-105.61% with relative standard deviations (RSDs) < 10 were obtained for both analytes. The rate of disappearance of total thiamethoxam residues in/on Swiss chard was best described by first-order kinetics with half-lives of 6.3 and 4.2 days. We predicted from the PHRL curves that if the residues were <19.21 or 26.98 mg/kg at 10 days before harvest, then total thiamethoxam concentrations would be below the maximum residue limits during harvest.

Ginseng gintonin activates the human cardiac delayed rectifier K+ channel: involvement of Ca2+/calmodulin binding sites.

Gintonin, a novel, ginseng-derived G protein-coupled lysophosphatidic acid (LPA) receptor ligand, elicits [Ca(2+)]i transients in neuronal and non-neuronal cells via pertussis toxin-sensitive and pertussis toxin-insensitive G proteins. The slowly activating delayed rectifier K(+) (I(Ks)) channel is a cardiac K(+) channel composed of KCNQ1 and KCNE1 subunits. The C terminus of the KCNQ1 channel protein has two calmodulin-binding sites that are involved in regulating I(Ks) channels. In this study, we investigated the molecular mechanisms of gintonin-mediated activation of human I(Ks) channel activity by expressing human I(Ks) channels in Xenopus oocytes. We found that gintonin enhances IKs channel currents in concentration- and voltage-dependent manners. The EC50 for the I(Ks) channel was 0.05 ± 0.01 µg/ml. Gintonin-mediated activation of the I(Ks) channels was blocked by an LPA1/3 receptor antagonist, an active phospholipase C inhibitor, an IP3 receptor antagonist, and the calcium chelator BAPTA. Gintonin-mediated activation of both the I(Ks) channel was also blocked by the calmodulin (CaM) blocker calmidazolium. Mutations in the KCNQ1 [Ca(2+)]i/CaM-binding IQ motif sites (S373P, W392R, or R539W)blocked the action of gintonin on I(Ks) channel. However, gintonin had no effect on hERG K(+) channel activity. These results show that gintonin-mediated enhancement of I(Ks) channel currents is achieved through binding of the [Ca(2+)]i/CaM complex to the C terminus of KCNQ1 subunit.

Effect of zinc oxide nanoparticles on dams and embryo-fetal development in rats.

This study investigated the potential adverse effects of zinc oxide nanoparticles (ZnO(SM20[-]) NPs; negatively charged, 20 nm) on pregnant dams and embryo-fetal development after maternal exposure over the period of gestational days 5-19 with Sprague Dawley rats. ZnO(SM20(-)) NPs were administered to pregnant rats by gavage at 0 mg/kg/day, 100 mg/kg/day, 200 mg/kg/day, and 400 mg/kg/day. All dams were subjected to caesarean section on gestational day 20, and all the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight at 400 mg/kg/day and decreased liver weight, and increased adrenal glands weight at 200 mg/kg/day and 400 mg/kg/day. However, no treatment-related difference in the number of corpora lutea, the number of implantation sites, the implantation rate (%), resorption, dead fetuses, litter size, fetal deaths, fetal and placental weights, and sex ratio were observed between the groups. Morphological examinations of the fetuses demonstrated no significant difference in the incidences of abnormalities between the groups. No significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that a 15-day repeated oral dose of ZnO(SM20(-)) was minimally maternotoxic at dose of 200 mg/kg/day and 400 mg/kg/day.

Prenatal development toxicity study of zinc oxide nanoparticles in rats.

This study investigated the potential adverse effects of zinc oxide nanoparticles ([ZnO(SM20(+)) NPs] zinc oxide nanoparticles, positively charged, 20 nm) on pregnant dams and embryo-fetal development after maternal exposure over the period of gestational days 5-19 with Sprague-Dawley rats. ZnO(SM20(+)) NPs were administered to pregnant rats by gavage at 0, 100, 200, and 400 mg/kg/day. All dams were subjected to a cesarean section on gestational day 20, and all of the fetuses were examined for external, visceral, and skeletal alterations. Toxicity in the dams manifested as significantly decreased body weight after administration of 400 mg/kg/day NPs; reduced food consumption after administration of 200 and 400 mg/kg/day NPs; and decreased liver weight and increased adrenal glands weight after administration of 400 mg/kg/day NPs. However, no treatment-related difference in: number of corpora lutea; number of implantation sites; implantation rate (%); resorption; dead fetuses; litter size; fetal deaths and placental weights; and sex ratio were observed between the groups. On the other hand, significant decreases between treatment groups and controls were seen for fetal weights after administration of 400 mg/kg/day NPs. Morphological examinations of the fetuses demonstrated significant differences in incidences of abnormalities in the group administered 400mg/kg/day. Meanwhile, no significant difference was found in the Zn content of fetal tissue between the control and high-dose groups. These results showed that oral doses for the study with 15-days repeated of ZnO(SM20(+)) NPs were maternotoxic in the 200 mg/kg/day group, and embryotoxic in the 400 mg/kg/day group.