Triadimenol Enantiomers Research Articles

Separation and determination of triadimefon and its metabolites triadimenol enantiomers in fruit puree by supercritical fluid chromatography.

A method was established for the separation and determination of triadimefon and its metabolite triadimenol enantiomer residues in major complementary fruit puree for infants and young children (banana puree, pineapple puree and grape puree) by supercritical fluid chromatography. After the samples were extracted with acetonitrile and purified with solid phase extraction cartridge, Acquity Trefoil CEL2 chiral chromatographic column was adopted for separation, and gradient elution was conducted at the flow rate of 1.0 mL/min under the mobile phase of supercritical carbon dioxide - 0.5% ammonia methanol; the detection wavelength was 220 nm and quantification was conducted with the external standard method. The limits of quantitation of triadimefon and triadimenol enantiomers were both 0.05 mg/kg, the linear ranges were 0.5-50 mg/L, and the linear correlation coefficients were greater than 0.9993. The recoveries in the spiked samples at 0.05, 0.2 and 3.0 mg/kg were from 80.1 to 106%, and the relative standard deviation reached 3.3-7.6%. The method is efficient, rapid, reproducible, and environmentally friendly, enabling accurate analysis of pesticide enantiomers, which can detect the enantiomer residues of triadimefon and its metabolite triadimenol in major complementary fruit puree for infants and young children. This article is protected by copyright. All rights reserved.

Enantioselective metabolism of triadimefon and its chiral metabolite triadimenol in lizards

Chinese lizards (Eremias argus) were exposed to separated R-(-)-triadimefon, S-(+)-triadimefon and racemic triadimefon to evaluate enantioselective accumulation of triadimefon. After single oral administration of R-(-)-triadimefon, S-(+)-triadimefon and racemic triadimefon, the time-concentration curves in different tissues were found to be different. Triadimefon enantiomers crossed the blood-brain barrier and brain is a main target organ. The residues of triadimefon enantiomers in fat were highest after 24h indicating that fat was the main tissue of accumulation. In racemic triadimefon exposure group, the enantiomer fractions of R-(-)-triadimefon in different tissues showed that the differences between R-(-)-triadimefon and S-(+)-triadimefon were significant in absorption and metabolism, but the differences became smaller in exclusion and accumulation. From the results of mathematical models, S-(+)-triadimefon was absorbed and eliminated faster than R-(-)-triadimefon, and R-(-)-triadimefon was easily distributed in the tissues and more easily converted into its metabolites. Furthermore, among the four enantiomers of triadimenol, SR-(-)-triadimenol produced by S-(+)-triadimefon may have the highest fungicidal activity and the strongest biological toxicity, RR-(+)-triadimenol produced by R-(-)-triadimefon was most likely to bioaccumulate in lizard. Identifying toxicological effects and dose-response relationship of SR-(-)-triadimenol and RR-(+)-triadimenol will help fully assess the risk of TF enantiomers use in the future. The results enrich and supplement the knowledge of the environmental fate of triadimefon enantiomers.

Tissue distribution and metabolism of triadimefon and triadimenol enantiomers in Chinese lizards (Eremias argus)

Triadimefon (TF, S-(+)-TF, R-(-)-TF) and its metabolite triadimenol (TN, TN-A1, A2 and TN-B1, B2) are two systemic fungicides and both of them are chiral pharmaceuticals which are widely used in agricultural industry. Many researches focused on the toxicity effects of triadimefon on mammals, while the ecotoxicological data of tiradimefon on reptiles is limited. In order to understand the toxicity mechanism of triadimefon in reptiles, the current study administrated S-(+)-TF or R-(-)-TF traidimefon (50mg/kgbw) to Chinese lizards (Eremias argus) respectively, the absorption, distribution of triadimefon and the formation of triadimenol were analysed at different sampling times. The metabolic pathways were demonstrated through relative gene expression using quantitative real-time PCR reaction. During the experiment time, triadimefon was quickly peaked to the maximum concentration within 12h in liver, brain, kidney, and plasma, eliminated slowly. The biotransformation in kidney was the lowest and fat possessed the worst degradation ability among others. The metabolite, triadimenol was detected in blood in 2h and reached to a plateau at about 12h in most organs (fat excepted), while the process of metabolism is stereoselective. The mainly metabolite in R-(-)-TF treated group was TN-B1, and TN-A2 in S-(+)-TF group which showed the selective metabolism to other species caused by environmental conditions, differences in the animal models and concentration of TF. The related gene expression of cyp1a1, cyp3a1 and hsd11β mRNA level in lizards showed different metabolic pathways in the liver and brain. Both P450s enzymes and 11β-hydroxysteroid dehydrogenase participated in metabolic reaction in liver, while no 11β-hydroxysteroid dehydrogenase pathway observed in brain. This diversity in liver and brain may cause different degradation rate and ecotoxicological effect in different organs.

Simultaneous enantioselective determination of triadimefon and its metabolite triadimenol in edible vegetable oil by gel permeation chromatography and ultraperformance convergence chromatography/tandem mass spectrometry.

A novel, sensitive, and efficient enantioselective method for the determination of triadimefon and its metabolite triadimenol in edible vegetable oil, was developed by gel permeation chromatography and ultraperformance convergence chromatography/tandem triple quadrupole mass spectrometry. After the vegetable oil samples were prepared using gel permeation chromatography, the eluent was collected, evaporated, and dried with nitrogen gas. The residue was redissolved by adding methanol up to a final volume of 1mL. The analytes of six enantiomers were analyzed on Chiralpak IA-3 column (150 × 4.6mm) using compressed liquid CO2-mixed 14% co-solvents, comprising methanol/acetonitrile/isopropanol = 20/20/60 (v/v/v) in the mobile phase at 30°C, and the total separation time was less than 4min at a flow rate of 2mL/min. Quantification was achieved using matrix-matched standard calibration curves. The overall mean recoveries for six enantiomers from vegetable oil were 90.1-97.3%, with relative standard deviations of 0.8-5.4% intra-day and 2.3-5.0% inter-day at 0.5, 5, and 50μg/kg levels. The limits of quantification were 0.5μg/kg for all enantiomers based on five replicate extractions at the lowest fortified level in vegetable oil. Moreover, the absolute configuration of six enantiomers had been determined based on comparisons of the vibrational circular dichroism experimental spectra with the theoretical curve obtained by density functional theory calculations. Application of the proposed method to the 40 authentic vegetable oil samples from local markets suggests its potential use in enantioselective determination of triadimefon and triadimenol enantiomers. Graphical Abstract Chemical structures and UPC(2)-MS/MS separation chromatograms of triadimefon and triadimenol.

Stereoselective metabolism, distribution, and bioaccumulation brof triadimefon and triadimenol in lizards

In this research, Chinese lizards (Eremias argus) were chosen as laboratory animal to evaluate the stereoselectivity in the processes of metabolism, distribution, and bioaccumulation of triadimefon. A validated chiral high-performance liquid chromatography coupled with triple quadruple mass spectrometry (HPLC–MS/MS) method was developed for determining enantiomers’ residues of parent compound triadimefon and its metabolite triadimenol in lizard blood and tissues. Pharmacokinetic results of single-does exposure suggested that S-(+)-triadimefon was metabolized easier than R-(−)-triadimefon, and RR-(+)-triadimenol was the main metabolic product of triadimefon. During the continuous exposure of two dose (40mg/kgbw·d and 200mg/kgbw·d), enantiomers of triadimefon and triadimenol were detected in all body compartments, with the highest triadimefon concentrations in brain. However, the triadimenol concentrations were not significantly different among the compartments. The concentrations of RS-(+)-triadimenol were negative correlated with concentrations of RR-(+)-triadimenol both in blood (r=−0.775, p=0.024) and liver (r=−0.834, p=0.02) in 200mg/kgbw·d group, which indicates that chiral conversion between enantiomers of triadimenol might exist in the metabolic process of triadimefon. In all the processes, the enantiomer fractions (EFs) of R-(−)-triadimefon and RR-(+)-triadimenol were significantly different from their natural ratios, 0.5 and 0.1, respectively, which proved that metabolism, bioaccumulation, and distribution of triadimefon and triadimenol in lizards were enantioselective. These results help enrich and supplement the knowledge of the stereoselective behaviour of triadimefon and triadimenol in reptile.

New mathematic model for predicting chiral separation using molecular docking: Mechanism of chiral recognition of triadimenol analogues

The purpose of this paper was to study the enantioseparation mechanism of triadimenol compounds by carboxymethylated (CM)-beta-CD mediated CE. All the enantiomers were separated under the same experimental conditions to study the chiral recognition mechanism using a 30 mM sodium dihydrogen phosphate buffer at pH 2.2 adjusted by phosphoric acid. The inclusion courses between CM-beta-CD and enantiomers were investigated by the means of molecular docking technique. It was found that there were at least three points (one hydrophobic bond and two hydrogen bonds) involved in the interaction of each enantiomer with the chiral selectors. A new mathematic model has been built up based on the results of molecular mechanics calculations, which could analyze the relationship between the resolution of enantioseparation and the interaction energy in the docking area. Comparing the results of the separation by CE, the established mathematic model demonstrated good capability to predict chiral separation of triadimenol enantiomers using CM-beta-CD mediated CE.

Separation of triadimefon and triadimenol enantiomers and diastereoisomers by supercritical fluid chromatography

The enantiomeric separation of triadimenol and triadimefon on a Chiralpak AD column using supercritical fluid chromatography, was studied in this work. The effect of different modifiers (methanol, ethanol and 2-propanol) was tested, with methanol and ethanol providing the best results for the enantiomeric separation of the two compounds. The enantioseparation of a mixture of triadimenol and triadimefon (six stereoisomers) was achieved in only 15 min using a gradient of ethanol, 200 bar, 35 °C and a flow-rate of 2 ml/min. The separation of triadimenol diastereoisomers on different achiral columns (diol, silica and ODS) was also investigated. In this case, the type of organic modifier to be used depended on the stationary phase, the Spherex Diol being the column that gave the best separation. Using this column, resolutions higher than 3 were obtained in analysis times of 5 min with any of the modifiers checked.

Comparative fate in soil of the enantiomers of triadimenol when applied individually to barley seed

AbstractThe systemic fungicide triadimenol is a mixture of four enantiomers which have different biological activities. Dissipation and metabolism of the individual enantiomers in soil were investigated after seed treatment. Forty‐nine days after 1R2S and 1S2S treatments, more of the radioactivity (87% for both) had dissipated from the seeds into the 0–10 cm soil layer than after the 1S2R (76%) and 1R2R (73%) treatments. After 1R2S treatment 56% of the radioactivity extracted from soil was accounted for as the parent isomer and 44% as its 1R2R epimer. After 1S2R treatment 76% of the radioactivity was in the parent form and 24% was converted to the 1S2S (17%) and 1R2R (7%) isomers.

The lipid compositions of two isolates of Cladosporium cucumerinum do not explain their differences in sensitivity to fungicides which inhibit sterol biosynthesis

AbstractIsolate 840905 of Cladosporium cucumerinum, when grown on agar or in liqiud medium, was sensitive to triadimenol, HWG 1608 (tebuconazole), fenpropimorph and pimaricin but relatively resistant to terbinafine. Conversely, isolate 49628 was sensitive to terbinafine but relatively resistant to the other fungicides. Changes in sterol composition following treatment with the fungicides reflected the known modes of action of each fungicide. When individual enantiomers of triadimenol were tested against isolate 840905 the order of activity in reducing mycelial growth was 1 S, 2R > 1R, 2R > 1R, 2S ≈︁ 1S, 2S, and this was paralleled by the depletion of ergosterol and the appearance of 14α‐methyl sterols. Isolate 49628 had a greater saturated:unsaturated fatty acid ratio than did isolate 840905 but no major changes in fatty acid composition of either isolate were induced by fungicide treatment. There appears to be no obvious explanation for the differences in fungicide sensitivity of the isolates in terms of their lipid compositions.

Comparative activity of the enantiomers of triadimenol and paclobutrazol as inhibitors of fungal growth and plant sterol and gibberellin biosynthesis

AbstractThe nature and degree of the biological activity shown by triadimenol and paclobutrazol are influenced considerably by the absolute configuration of the two asymmetric carbon atoms present in the molecules. The order of the activity of triadimenol enantiomers was found to be: fungitoxicity—1S, 2R > 1R, 2R > 1R, 2S > 1S, 2S; inhibition of gibberellin biosynthesis—1R, 2S > 1S, 2S > 1R, 2R > 1S, 2R; and inhibition of plant sterol biosynthesis—1R, 2S≈1S, 2R > 1R, 2R > 1S, 25.The relative activity of paclobutrazol enantiomers was: fungitoxicity— 2R, 3R > 2S, 3R > 2R, 3S≈2S, 3S; inhibition of gibberellin biosynthesis—2S, 3S > 2R, 3S > 2R, 3R > 2S, 3R; and inhibition of plant sterol biosynthesis—2R, 3S > 2R, 3R > 2S, 3S > 2S, 3R. These data indicate that the R configuration at the chiral carbon bearing the hydroxyl group is the prime determinant for fungitoxicity whereas enantiomers having the S configuration at this carbon are effective inhibitors of gibberellin biosynthesis. This agrees well with published data for the structurally related vinylazoles.Plant sterol C‐14a demethylation was not always inhibited by enantiomers having high fungicidal activity thus indicating that the structural features necessary for binding to the plant C‐14a demethylase may differ from those needed for the analogous fungal enzyme.

The enantiomeric composition of triadimenol produced during metabolism of triadimefon by fungi: III. Relationship with sensitivity to triadimefon

Fifteen species of fungi, grown in shake culture in a liquid nutrient medium containing a 50:50 mixture of the 1 R and 1 S enantiomers of triadimefon, reduced triadimefon to triadimenol, the extent of reduction varying from <1% to >95% according to species. Each produced its own characteristic pattern of two or more of the four possible enantiomers of triadimenol and the stereoselectivity and stereospecificity of the reduction is discussed. The sensitivity of each fungus to individual enantiomers and a mixture of enantiomers of triadimefon and of triadimenol was assessed. Three broadly defined groups of fungi were found: (i) sensitive to both triadimefon and tridimenol, (ii) insensitive to both, and (iii) insensitive to triadimefon but moderately sensitive to triadimenol. In many cases it was possible to predict, at least semiquantitatively, the sensitivity of an organism to triadimefon from a knowledge of its characteristic metabolism to triadimenol and its sensitivity to the individual triadimenol enantiomers. No evidence for synergism or antagonism was found.