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The rapid evolution of antimicrobial resistant genes (AMRs) in water resources is well correlated to the persistent occurrence of ciprofloxacin in water. For the first time, encapsulated nanoscale zerovalent iron (nZVI) with a shell of magnesium hydroxide (Mg/Fe0) was used to adsorb ciprofloxacin from water. Optimization of the removal conditions exhibited that 5% was the optimum mass ratio between magnesium hydroxide and nZVI [Mg(OH)2/nZVI)] as more than 96% of 100 mg L−1 of ciprofloxacin was removed. In addition, 0.5 g L−1 of Mg/Fe0 showed an extraordinary performance in removing ciprofloxacin over a wide range of pH (3–11) with removal efficiencies exceeded 90%. Kinetic analysis displayed that the kinetic data was well described by both Pseudo first-order and second-order models. Also, the equilibrium data was well fitted by Freundlich isotherm model. In addition, thermodynamic analysis evidenced that the removal of ciprofloxacin by Mg/Fe0 was exothermic, and spontaneous. The experiments also revealed that physisorption and chemisorption were the responsible mechanisms for ciprofloxacin removal. The proposed treatment system remediated 10 litters of 100 mg L−1 of ciprofloxacin solution with 100% overall removal efficiency. This treatment system could be a promising and practical solution to decrease ciprofloxacin concentration in different water bodies.

The development of antimicrobial resistance genes (AMRs) in water was globally accelerated due to the occurrence of ciprofloxacin (CIP) in water. This study aims to precipitate iron nanoparticles (Fe0) on the surface of titanium nanowires (TNWs) through a chemical process to overcome the limitations of Fe0 and efficiently remove CIP from water. TEM and XRD results confirmed the successful synthesis of Fe0 and TNWs. They also proved the successful deposition and dispersion of Fe0 on TNWs. Several (Fe0/TNW) nanocomposites were synthesised with different percentages of TNWs (5, 10, 20, 30, and 50%) to define the best TNWs ratio that will decrease the aggregation of Fe0 nanoparticles and achieve an outstanding removal efficiency of CIP. (Fe0/TNW) nanocomposite with 20% of TNW was nominated as the best nanocomposite because it demonstrated a promising performance, compared with other nanocomposites, by removing more than 67% of CIP with insignificant desorption behaviour during the treatment period (120 min). Dosage of (20%-Fe0/TNW), initial pH of CIP solution and reaction temperature were optimized through a group of batch experiments to efficiently remove CIP from water. The optimum removal of CIP was obtained by 1 g L−1 of (20%-Fe0/TNW) nanocomposite at initial pH of 7 under 35 °C.

The asymmetric Kharasch addition reaction was studied by using water as an environmentally friendly solvent. The reaction of styrene with BrCCl3 catalyzed by chiral rhodium species, “RhCl[(–)-DIOP]”, gave the corresponding adduct in moderate chemical and asymmetric yields “on water”, where all the reactants float on water. By reinvestigation of the literature procedure, the chemical and asymmetric yields “on water” were compared with those obtained in organic solvents. The reaction with FeCl2 / (–)-DIOP catalyst was examined to look at the metal effect. Possible reaction mechanisms were proposed based on these results. (93 words).

The selectivity of palladium catalysed hydrogenation can be improved by adding a homogeneous modifier (or poison) such as quinoline to the reaction mixture. Although such selectivity improvement by modifiers (selective catalyst poisoning) has been known for decades, we still know little about them. We, ultimately, cannot select a modifier to improve a particular process. In this study, 21 types of modifiers are screened for the semi-hydrogenation of alkynes with varying catalyst type, reaction time, and target substrate using an automated flow reactor system. All of the studied variables changed affected hydrogenation activity and selectivity confirming the effectiveness of a multi-parameter optimization. 1,10-phenanthroline marked the best selectivity beyond quinoline. The density functional theory (DFT) calculations suggest that 1,10-phenanthroline has a remarkable ability to adsorb on the irregular surface of the catalyst that effects undesirable reaction.\ud \ud

Herein, the influence of group 1 and 2 metal cations on base-catalyzed dehydrogenative coupling of formate to form oxalate is reported. Treatment of sodium formate with a various types of bases (group 1 and 2 metal carbonates or metal hydroxides) revealed that, compared with carbonate salts, group 1 metal hydroxides behaved as efficient bases for the formation of oxalate, in which cesium hydroxide (CsOH) showed the best catalytic activity. DFT calculation for the reaction mechanism suggested that its kinetic advantage was generated from not only an increase of basicity but also destabilization of the intermediate species due to Na/Cs mixed cation system. The effect of cations in formate salts were also discussed both experimentally and theoretically, in which the yield of oxalic acid depended on thermodynamic stability of both products (oxalate salts) and intermediates.

Global iron and steel production continues to expand. The iron-making industry is, however, one of the main contributors to global warming due to its reliance on fossil fuel-based high temperature ...

The μ3-η2-iminoacyl-μ3-hexylidyne complex, [(Cp*Ru)3(μ3-CC5H11)(μ3-η2-HN═CMe)(μ-H)] (2a) (Cp* = η5-C5Me5), was prepared by the reaction of the μ3-η2:η2(⊥)-hexyne complex, [{Cp*Ru(μ-H)}3(μ3-η2:η2-nB...

Removal of cesium from waters is an emerging issue after the accident at Fukushima Daiichi Nuclear Power Plant. In this work, new nanoscale zero valent iron–zeolite (nZVI–Z) and nano-Fe/Cu–zeolite (nFe/Cu–Z) composites for cesium removal were fabricated through ion exchange process followed by liquid-phase reduction. The characterization by XRD and SEM-EDS demonstrated that nZVI and nano-Fe/Cu particles were successfully loaded onto zeolite. The performance of the composites for the removal of cesium from aqueous solutions with the ability to separate the adsorbent magnetically was investigated. Batch sorption experiments were systematically carried out to assess the effect of different parameters such as pH, initial concentration, contact time, adsorbent dosage and temperature. The removal kinetics of cesium was adequately described by the pseudo-second-order kinetic model, which indicates that the uptake mechanism was chemisorption. The rate constant values for adsorption by nFe/Cu–Z were greater than the values obtained for nZVI–Z, meaning that nFe/Cu–Z had faster adsorption kinetics towards cesium solutions. The equilibrium adsorption data gave better mathematical fitting towards Langmuir and Freundlich isotherm models, where the maximum adsorption capacity of nFe/Cu–Z (77.51 mg/g) was found to be higher than that for nZVI–Z (71.12 mg/g). The observed thermodynamic parameters showed that the adsorption of cesium was endothermic process and spontaneous in nature. The composites were efficiently recovered from solution after the adsorption experiments by an easy, simple and rapid magnetic separation. The obtained results suggested that both composites could be used as a promising technique for the treatment of waters containing cesium.

Studies on the deactivation mechanism of the reaction of N,N-dialkylamides with TMDS catalyzed by Vaska’s complex, IrCl(CO)(PPh3)2 (1a), triggered the discovery of highly active Ir-PPh3 catalysts: photochemically activated 1a and thermally activated IrCl(PPh3)3 (8). Both catalysts showed excellent activity toward the selective conversion of a variety of N,N-dialkyl-, N-alkyl-N-aryl-, and N,N-diarylamides to the corresponding enamines with low catalyst loadings. The 14-electron species “ClIr(PPh3)2”, which is stabilized by solvents or reactants in the actual catalytic reactions, could be involved in the catalysis, which produces “HIr(PPh3)2” and “SiIr(PPh3)2” (Si = Me2HSiOMe2Si−) species in the catalytic cycle. An in situ generation method for the “ClIrL2” species was established by simply mixing [IrCl(η4-COD)]2 with PPh3 or other phosphorus ligands, which realized the facile large-scale syntheses of enamines.

Radioactive cesium was resealed to the environment as a result of many nuclear incidents. An effective treatment system is urgently needed to safely handle radioactive cesium-contaminated waters. Based on nanoscale zerovalent iron (nZVI) and zeolite, nine adsorbents were synthesized and applied to remove cesium from aqueous solutions. Magnetic zeolite composite (Ze/Fe0) was selected as the ideal adsorbent for treating cesium contaminated waters in a lab-scale continuous treatment system (LSCTS). The optimization process of the (Ze/Fe0) composite revealed that 1:1 is the optimum mass ratio between zeolite and nZVI. Furthermore, the optimization process proved that the initial pH and temperature have no significant effect on the adsorption of cesium by (Ze/Fe0) composite and the optimum dosage of (Ze/Fe0) composite is 5 g L−1. XRD and SEM results showed that the (Ze/Fe0) composite has an irregular shape with a poor crystalline structure. Kinetic and equilibrium data were best described by pseudo second order and Freundlich isotherm models. Seawater and groundwater experiments illustrated that the removal of cesium by (Ze/Fe0) composite was inhibited due to the existence of competing cations. Eight cycles of LSCTS were performed to examine the performance of (Ze/Fe0) composite in treating continuous streams of cesium contaminated waters. In all cycles except the cycle of treating contaminated seawater, LSCTS succeed to treat continuous flows of 1 mg L−1 cesium contaminated water with 100% overall removal efficiency. For treating contaminated seawater, pre-treatment unit is required to reduce the salinity of the contaminated seawater before staring the treatment process.

A triruthenium complex containing μ3-η2(||)-benzyne and μ3-sulfido ligands, [(Cp*Ru)3(μ3-S){μ3-η2(||)-C6H4}(μ-H)] (2), was synthesized by the reaction of [(Cp*Ru)3(μ3-S)(μ-H)3] (1) with benzene. Although 2 was stable toward oxygen and water, two-electron oxidation of 2 with a Ag(I) salt in the presence of water afforded the dicationic μ-hydroxo complex [(Cp*Ru)3(μ3-S){μ3-η2(||)-C6H4}(μ-OH)]2+ (3). Treatment of 3 with amine resulted in the deprotonation of the μ-hydroxo ligand, and an unsaturated monocationic complex, [(Cp*Ru)3(μ3-S)(μ3-OC6H4-κO,κC)]+ (4), which possesses a μ3-cyclohexadienonediyl ligand, was formed via reductive C–O bond formation between the μ3-benzyne and transient μ-oxo ligands. Phenol was extruded from the Ru3 cluster upon the hydrogenation of 4 via the formation of a μ3-phenoxo complex, [(Cp*Ru)3(μ3-S){μ3-OPh}(μ-H)]+ (5). The cyclic voltammogram of 2 shows two reversible one-electron redox waves, and a dicationic μ3-benzyne complex, [(Cp*Ru)3(μ3-S){μ3-η2:η2(⊥)-C6H4}(μ-H)]2+(8), was s...

Following the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, radioactive cesium was released into the environment in large amounts and heavily contaminated drinking water in Fukushima and neighboring prefectures. In this research, the capability of nanoscale zero valent iron (nZVI) and bimetallic nano-Fe/Cu particles for cesium removal from aqueous solutions was evaluated for the first time. The nanoparticles were characterized by TEM, XRD, SEM-EDS and BET-N2 adsorption. The effect of several variables such as initial cesium concentration, contact time, pH, temperature, competing cations and dosage of the nanoparticles on the sorption behavior of cesium was studied using a batch technique. The obtained results showed that nZVI and nano-Fe/Cu particles displayed effective performance for removal of cesium. For both nanoparticles, the removal efficiency exceeded 99% at initial cesium concentration of 1 mg/L and 1 g/L doses. The experimental data were well fitted to the pseudo-second-order kinetic model, which means that the overall rate constant of cesium sorption process was controlled by chemisorption. The rate constant of nano-Fe/Cu particles was larger than that of nZVI, indicating a faster kinetic sorption by nano-Fe/Cu particles. The thermodynamic parameters indicated exothermic and spontaneous nature of the sorption process. The Langmuir, Freundlich and Redlich-Peterson isotherm models were also used to fit the equilibrium data. nZVI and nano-Fe/Cu particles exhibited excellent selective sorption toward cesium in the simulated contaminated water after Fukushima accident. The current work demonstrated that nZVI and nano-Fe/Cu particles can be considered as promising materials for cesium removal from contaminated waters.

Palladium-catalyzed reactions of dodecamethylcyclohexasilane [(SiMe2)6] (1) with alkynes led to efficient preparation of 1,1,4,4-tetramethyl-1,4-disilacyclohexadienes (3). The reactions were best catalyzed by Pd(0) species generated from Pd2(dba)3·CHCl3 and 1-isocyanoadamantane (AdNC). Terminal and internal alkynes bearing aryl and alkyl substituents could be used as substrates, and the reaction allowed gram-scale preparation of 3. A dimethylsilylene (Me2Si:) species, generated by activation of Si–Si bonds in 1 by Pd(0) species, was involved in the reaction mechanism. The DFT calculations suggest that oxidative addition of Si–Si bonds in 1 to Pd(CNAd)2 species is followed by extrusion of a Me2Si═Pd(CNAd) intermediate. Reaction of the resulting palladium-coordinated silylene with an alkyne forms a silacyclopropene, which dimerizes to give 3. The extrusion is accompanied by ring contraction of 1 to generate (SiMe2)5, which also contributes to formation of 3 and (SiMe2)4 by the Pd(0)-catalyzed reaction with ...

A disilaruthenacyclic complex (1) showed extremely high catalytic activity for hydrosilane reduction of aldehydes and ketones to silyl ethers and secondary and tertiary amides to the corresponding amines. An σ-CAM mechanism was proposed to explain the activity.

The hydrogenation of alkenes catalyzed by disilametallacyclic carbonyl complexes of iron, ruthenium or osmium was studied experimentally and theoretically. The disilaruthenacycle 2 with two CO ligands in the trans-configuration was prepared, characterized, and its ability to catalyze hydrogenation was studied. Similar to the corresponding iron analogue 1 in which the CO ligands are in the cis-configuration, 2 contains a H2MSi4 core with Si⋯H⋯Si SISHA (secondary interaction of silicon and hydrogen atoms) and catalyzed the hydrogenation of several alkenes under mild conditions. DFT calculations of 1 and 2 with cis- and trans-CO configurations (cis-1, trans-1, cis-2 and trans-2) revealed that the mechanism of ethylene hydrogenation comprises three catalytic cycles, and a key step involves the H-H bond of H2 being activated by an M-Si bond through oxidative hydrogen migration. These mechanisms are a variety of σ-CAM (σ-complex-assisted metathesis) mechanisms. Further calculations suggest that these catalytic ...

High functional group compatibility of iridium-catalyzed synthesis of enamines from amides and 1,1,3,3-tetramethyldisiloxane (TMDS) realized facile access of a series of donor (D)-π-acceptor (A)-conjugated enamines, in which enamine behaves as a donor functional group. The amide precursors containing reducible functional groups, such as halogen, carbonyl, and nitro groups, underwent reaction with TMDS to give the corresponding enamines in high yields. In most cases, chemoselective hydrosilane reduction of the amide group occurred while other reducible groups remained intact. Absorption and emission properties including solvatochromic behavior for the resulting D-π-A-conjugated enamines were determined using UV-visible and fluorescent spectra, which provided an understanding of the donor properties of the CH═CHNPh

Iridium-catalyzed hydrosilylation of amides with 1,1,3,3-tetramethyldisiloxane (TMDS) allows access to silylhemiaminals, which are often spontaneously converted to aldenamines. Iridium(I) phosphine species generated from IrCl(CO)(PPh3)2, IrCl(PPh3)3, or a mixture of [IrCl(COD)]2 and phosphorous ligands showed high catalytic activity for this reaction protocol, which demonstrated remarkable compatibility toward other reducible functional groups such as ketone and ester groups. This reaction enables the synthesis of π-conjugate enamines having hole-transport properties by appropriate selection of the iridium catalyst. Easy access to silyl hemiaminals and enamined stimulated other research groups to discover new reductive C–C bond-forming reactions to transform amides to amine derivatives, which can be applied to the synthesis of complex alkaloid molecules.

Disilaferra- and disilaruthenacyclic complexes containing mesityl isocyanide as a ligand, 3′ and 4′, were synthesized and characterized by spectroscopy and crystallography. Both 3′ and 4′ showed excellent catalytic activity for the hydrogenation of alkenes. Compared with iron and ruthenium carbonyl analogues, 1′ and 2′, the isocyanide complexes 3′ and 4′ were more robust under the hydrogenation conditions, and were still active even at higher temperatures (∼80 °C) under high hydrogen pressure (∼20 atm). The iron complex 3′ exhibited the highest catalytic activity toward hydrogenation of mono-, di-, tri-, and tetrasubstituted alkenes among currently reported iron catalysts. Ruthenium complex 4′ catalyzed hydrogenation under very mild conditions, such as room temperature and 1 atm of H2. The remarkably high catalytic activity of 4′ for hydrogenation of unfunctionalized tetrasubstituted alkenes was especially notable, because it was comparable to the activity of iridium complexes reported by Crabtree and Pfa...

The appropriate design of a ligand (L) in IrCl(CO)(L)2 (4) realized the efficient synthesis of π-conjugated enamines possessing hole-transport properties. The iridium complex with electron-withdrawing phosphorus ligands catalyzed the hydrosilylation of amides to the corresponding silylhemiaminals, which were transformed to the enamines by heat or by treatment with acids. High catalytic efficiency (TON > 10,000) was achieved, which made it possible for the residual iridium in the enamine product to be below 20 ppb.

Efficient separation of strontium ions (Sr2+) from waters has become a critical technological requirement after the nuclear accident at Fukushima Daiichi power station. In the present investigation, new nanocomposites of zero valent iron nanoparticles–zeolite (nZVI–Z) and nano-Fe/Cu–zeolite (nFe/Cu–Z) were synthesized via a simple liquid-phase reduction approach and tested to determine their effectiveness in the sorptive removal of Sr2+ from aqueous solutions. The sorption of Sr2+ on both nanocomposites was studied in a batch sorption mode as a function of various environmental conditions such as initial Sr2+ concentration, contact time, pH, temperature, dosage of sorbent and competing cations (Na+, K+, Mg2+ and Ca2+). The results indicated that initial pH and temperature were significant for Sr2+ sorption on both nanocomposites. The Sr2+ sorption efficiency increases with the increase in nanocomposite dosage and decreases with the Sr+2 concentration. It was also found that although the sorption of Sr2+ was decreased by the presence of coexisting cations, the nanocomposites still exhibited high uptake capacity of Sr2+ ions. The Sr2+ sorption kinetics can be satisfactorily fitted by a pseudo-second-order kinetic model. The sorption isotherm data were well predicted using the Langmuir model. The maximum sorption capacity for nFe/Cu–Z was found to be 88.74 mg/g, which was greater than that for nZVI–Z (84.12 mg/g). In addition to the high sorption capacity, the nanocomposites could be easily separated from aqueous media after Sr2+ sorption using an external magnetic field. The calculated thermodynamic parameters such as ∆H°, ∆S° and ∆G° revealed the endothermic and spontaneous nature of the sorption process. The nanocomposites were also applied in a real seawater medium. The present study confirmed that the prepared nZVI–Z and nFe/Cu–Z nanocomposites could be employed as promising methods for the removal of Sr2+ from wastewater streams.

The mechanisms associated with the hydrogenation of alkenes catalyzed by the iron complex Fe(cis-CO)2{o-(SiMe2)2C6H4}2(H)2 (1) were investigated by DFT calculations. The complex 1 has a structure in which the iron center is bonded to four silicon atoms and two hydrides. Secondary Si···H···Si interactions were also observed. The exchange of a 1,2-bis(dimethylsilyl)benzene ligand with ethylene and hydrogen gives a disilaferracycle bearing η2-(CH2═CH2) and η2-H2 ligands. The catalytic cycle initiated from the disilaferracycle involves cleavage of a H–H linkage assisted by an Fe–Si bond to form Fe–H and η1-(H–Si) moieties (step 1), hydrogen migration from the Fe–H group to the η2-(CH2═CH2) ligand which accomplishes the insertion of ethylene into the Fe–H bond (step 2), and reaction of the resulting β-agostic ethyl moiety with the η2-(H–Si) group to form ethane on the iron atom (step 3). The octahedral geometry of 1 as well as the presence of π-acidic CO ligands and Fe–Si σ-bonds contributes to all of the cata...

A mixture of an iron or a cobalt carboxylate and an isocyanide ligand catalyzed the hydrosilylation of alkenes with hydrosiloxanes with high efficiency (TON >10(3)) and high selectivity. The Fe catalyst showed excellent activity for hydrosilylation of styrene derivatives, whereas the Co catalyst was widely effective in reaction of alkenes. Both of them catalyzed the reaction with allylic ethers. Chemical modification and cross-linking of silicones were achieved by choosing the right catalyst and reaction conditions.

A triruthenium complex containing μ3-η2(∥)-ethyne and μ3-methylidyne ligands, (CpRu)3{μ3-η2(∥)-HC≡CH}(μ3-CH)(μ-H)2 (2a), was synthesized via the treatment of {Cp*Ru(μ-H)}3(μ3-H)2 (3) (Cp* = η5-C5Me5) with propene. In the low-temperature region, VT 1H NMR spectra showed that complex 2a is in equilibrium with a nonclassical μ3-vinyl complex, (CpRu)3(μ3-η2:η2-HC═CH2)(μ3-CH)(μ-H) (5a), which features an interaction between one of the β-vinyl protons and a Ru center. The presence of the unusual 3c-2e interaction of the β-C–H bond of the vinyl group is strongly supported by the small JC–H value (98 Hz) found for the β-carbon as well as the small JH–H value for the α-vinyl proton. Treatment of the equilibrated mixture of phenyl-substituted complexes (CpRu)3{μ3-η2(∥)-HC≡CPh}(μ3-CH)(μ-H)2 (2b) and (CpRu)3(μ3-η2:η2-HC═CHPh)(μ3-CH)(μ-H) (5b) with tBuNC afforded a μ-styryl complex, (CpRu)3(μ-η2-HC═CHPh)(μ3-CH)(μ-tBuNC)(μ-H) (6), while analogous treatment of 2a and 5a resulted in the formation of μ3-dimetalloallyl com...

Triruthenium complex 2 containing a perpendicularly coordinated 1-pentyne ligand, which is one of the key intermediates of the reaction of triruthenium pentahydrido complex 1 with n-pentane, reacts with benzene to yield μ3-benzyne–μ3-pentylidyne complex 5 by C–H bond activation. β-H elimination form the μ3-penytylidyne ligand occurred upon heating to yield μ3-pentenylidene complex 6, which was followed by the formation of closo-ruthenacyclopentadiene complex 8 by the connection of the two hydrocarbyl moieties placed on each face of the triruthenium plane with partial metal–metal bond breaking. Treatment of 8 with pressurized hydrogen resulted in exclusive liberation of n-pentylbenzene, which is difficult to synthesize by conventional Friedel–Crafts alkylation. These sequential transformations correspond to the formation of linear alkylbenzene by the reaction of pentane with benzene on a trimetallic plane. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Deep neck infection (DNI) is an emergent otolaryngologic disease. We examined 69 patients, 52 males and 17 females, with DNI, who were treated in our hospital between 1995 and 2004. The mean age of DNI patients is 50.0 years old and peak incidence is in the sixth decade. Twenty patients suffered from diabetes mellitus (DM). The primary lesion of DNI was found in the tonsils in 34 cases, the oral cavity in 16 cases, the pharynx in 12 cases, and other regions in 7 cases, respectively. Among 69 DNI patients, infection remained in the suprahyoid region in 31 cases, whereas it extended to the infrahyoid region in 33 cases and to the mediastinum in 5 cases. The titer of serum C-reactive protein (CRP) and the duration of admission were considered parameters of DNI severity. CRP was significantly higher and the duration of admission was significantly longer in elderly patients, in patients with DM, and in patients with infrahyoid and mediastinal DNI, whereas no significant difference was found between males and females, and among the primary lesions. Therefore, we consider that age, DM, and the extension of DNI are important factors determining the severity of DNI. We also refer to the etiology, diagnosis, treatment and complications of DNI.

In this article we describe 5 rare cases of mumps-associated pharyngolaryngeal edema. To the best of our knowledge, this report includes the first case of mumps-associated pharyngolaryngeal edema in a patient who had previously received mumps vaccination, and these cases represent the sixth report of mumps-associated pharyngolaryngeal edema in the English literature. All 5 of our patients with mumps infection were adults and manifested airway stenosis due to pharyngolaryngeal edema. This edema responded favorably to steroid treatment without tracheotomy. We conclude that a pharyngolaryngeal examination is recommended for patients with mumps infection. Steroid treatment is usually effective against pharyngolaryngeal edema; however, in certain cases tracheotomy may be inevitable.

Effects of folic acid (FA) and folinic acid (FNA) on the embryotoxicity of pyrimethamine (PYR), an antifolate drug, were examined in mice. PYR and FA were administered orally, and FNA was injected intraperitonially for 7 days from day 9 to 15 of pregnancy. The incidence of embryotoxicity including intrauterine deaths and malformations, was 33.5 % in the PYR 50 mg/kg/day group. However, all the fetuses were resorbed in the PYR 50 + FA 50 mg/kg/day group, and FA potentiated the embryotoxicity of PYR. On the contrary, FNA reduced the embryotoxicity of PYR (PYR 50 + FNA 10mg/kg/day; 8.5%). Plasma concentrations of PYR and 5-methyltetrahydrofolic acid (5MF), a principal form of folate in plasma, were determined after single oral administration of PYR 50 mg/kg with or without FA 50 mg/kg to non-pregnant mice. Plasma 5MF concentration decreased drastically in the group receiving PYR with FA, compared with the PYR alone group. The pharmacokinetics of PYR were not affected by co-administration of FA. Therefore, we consider that the potentiated embryotoxicity of PYR by oral FA results from a decrease of plasma 5MF concentration in dams.