Terminal residue and dietary intake risk assessment of prothioconazole-desthio and fluoxastrobin in wheat field ecosystem.

BACKGROUND: Wheat is one of the most important cereal crops worldwide, and use of fungicides is an essential part of wheat production. Both prothioconazole and fluoxastrobin give excellent control of important seed and soilborne pathogens. The combination of these two fungicides shows a complementary mode of action and has a wide usage around the world. But the residue levels of these fungicides in the wheat matrix are still unknown. RESULTS: In the current study, a simple, low-cost and highly sensitive method using modified QuECHERS procedure combined with high-performance liquid chromatography-tandem mass spectrometry was developed to simultaneously quantify E- and Z-fluoxastrobin and the main metabolite prothioconazole-desthio of prothioconazole in the wheat matrix. The recoveries of prothioconazole-desthio, E-fluoxastrobin and Z-fluoxastrobin ranged from 84% to 101%, with relative standard deviation of less than 13.2%. The terminal residues of prothioconazole-desthio and E- and Z-fluoxastrobin were studied in wheat grain and straw under field conditions. The results showed that the terminal residue of the target compounds ranged from <0.01 to 0.029 mg kg-1 and <0.05 to 7.6 mg kg-1 in wheat grain and straw (expressed as dry weight), respectively. The risk quotients of prothioconazole-desthio and fluoxastrobin were 0.2% and 3.2%. CONCLUSIONS: The residue levels of the target analytes in wheat grain were lower than the maximum residue limits recommended by the Chinese Ministry of Agriculture. And the calculated risk quotient values were far below 100%, indicating a low dietary intake health risk to consumers. © 2021 Society of Chemical Industry.

Discovery of IPN60090, a Clinical Stage Selective Glutaminase-1 (GLS-1) Inhibitor with Excellent Pharmacokinetic and Physicochemical Properties.

Inhibition of glutaminase-1 (GLS-1) hampers the proliferation of tumor cells reliant on glutamine. Known glutaminase inhibitors have potential limitations, and in vivo exposures are potentially limited due to poor physicochemical properties. We initiated a GLS-1 inhibitor discovery program focused on optimizing physicochemical and pharmacokinetic properties, and have developed a new selective inhibitor, compound 27 (IPN60090), which is currently in phase 1 clinical trials. Compound 27 attains high oral exposures in preclinical species, with strong in vivo target engagement, and should robustly inhibit glutaminase in humans.

Discovery of 1,2,3-triazole based quinoxaline-1,4-di-N-oxide derivatives as potential anti-tubercular agents.

A series of thirty one novel 2-(((1-(substituted phenyl)-1H-1,2,3-triazol-4-yl)methoxy)carbonyl)-3-methylquinoxaline-1,4-dioxide (7a-l), 3-(((1-(substituted phenyl)-1H-1,2,3-triazol-4-yl)methoxy)carbonyl)-6-chloro-2-methylquinoxaline-1,4-dioxide (8a-l) and 2-(((1-(substituted phenyl)-1H-1,2,3-triazol-4-yl)methoxy)carbonyl)-6,7-dichloro-3-methylquinoxaline-1,4-dioxide (9a-g) analogues were synthesized, characterized using various analytical techniques and single crystal was developed for the compounds 8 g and 9f. Synthesized compounds were evaluated for in vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv strain and two clinical isolates Spec. 210 and Spec. 192. The titled compounds exhibited minimum inhibitory concentration (MIC) ranging from 30.35 to 252.00 µM. Among the tested compounds, 8e, 8 l, 9c and 9d exhibited moderate activity (MIC = 47.6 - 52.0 µM) and 8a exhibited significant anti-tubercular activity (MIC = 30.35 µM). Furthermore, 8e, 8 l, and 9d were found to be less toxic against human embryonic kidney, HEK 293 cell lines. Finally, a docking study was also performed using MTB DNA Gyrase (PDB ID: 5BS8) for the significantly active compound 8a to know the exact binding pattern within the active site of the target enzyme.

Absorption, distribution, metabolism and excretion of molidustat in healthy participants.

The absorption, distribution, metabolism and excretion of molidustat were investigated in healthy male participants. In study 1, a mass balance study, radiolabelled molidustat 25 mg (3.57 MBq) was administered as an oral solution (n = 4). Following rapid absorption, molidustat-related radioactivity was predominantly distributed in plasma rather than in red blood cells. The total recovery of the administered radioactivity was 97.0%, which was mainly excreted renally (90.7%). Metabolite M-1, produced by N-glucuronidation, was the dominant component in plasma (80.2% of the area under the concentration-time curve for total radioactivity) and was primarily excreted via urine (~85% of dose). Only minor amounts of unchanged molidustat were excreted in urine (~4%) and faeces (~6%). Study 2 investigated the absolute bioavailability and pharmacodynamics of molidustat (part 1, n = 12; part 2, n = 16). Orally administered molidustat immediate release tablets had an absolute bioavailability of 59%. Following intravenous administration (1, 5 and 25 mg), total body clearance of molidustat was 28.7-34.5 L/h and volume of distribution at steady state was 39.3-50.0 L. All doses of molidustat transiently elevated endogenous erythropoietin levels, irrespective of the route of administration. Molidustat was considered safe and well tolerated at the administered doses.

In Vivo Evaluation of Isoprenoid Triazole Bisphosphonate Inhibitors of Geranylgeranyl Diphosphate Synthase: Impact of Olefin Stereochemistry on Toxicity and Biodistribution.

The enzyme geranylgeranyl diphosphate synthase (GGDPS) synthesizes the 20-carbon isoprenoid geranylgeranyl pyrophosphate, which is used in geranylgeranylation reactions. We have demonstrated that GGDPS inhibitors in multiple myeloma (MM) cells disrupt Rab geranylgeranylation, leading to inhibition of monoclonal protein trafficking, induction of the unfolded protein response pathway (UPR), and apoptosis. We have previously reported preclinical studies with the GGDPS inhibitor VSW1198, which is a mixture of homogeranyl/homoneryl triazole bisphosphonates. Additional structure-function efforts have led to development of the α-methylated derivatives RAM2093 (homogeranyl) and RAM2061 (homoneryl). As little is known regarding the impact of olefin stereochemistry on drug properties in vivo, we pursued additional preclinical evaluation of RAM2093 and RAM2061. In MM cell lines, both isomers induce activation of UPR/apoptotic markers in a concentration-dependent manner and with similar potency. Single-dose testing in CD-1 mice identified a maximum tolerated i.v. dose of 0.5 mg/kg for RAM2061 and 0.3 mg/kg for RAM2093. Liver toxicity was the primary barrier to dose escalation for both compounds. Disruption of geranylgeranylation in vivo was confirmed after multidose administration of either compound. Pharmacokinetic studies revealed plasma terminal half-lives of 29.2 ± 6 (RAM2061) and 22.1 ± 4 hours (RAM2093). Relative to RAM2061, RAM2093 levels were significantly higher in liver tissue but not in other tissues. Using MM.1S flank xenografts, we observed a significant reduction in tumor growth in mice treated with RAM2061 relative to controls. Collectively, these studies reveal olefin stereochemistry-dependent effects on GGDPS inhibitor biodistribution and confirm the in vivo efficacy of this novel therapeutic approach. SIGNIFICANCE STATEMENT: These studies reveal olefin stereochemistry-dependent effects on the in vivo properties of two novel triazole bisphosphonate inhibitors of geranylgeranyl diphosphate synthase and demonstrate the therapeutic potential of this class of inhibitors for the treatment of multiple myeloma.

Lecithin Microemulsion Lipogels Versus Conventional Gels for Skin Targeting of Terconazole: In Vitro, Ex Vivo, and In Vivo Investigation.

Topical treatment of fungal infections has several superiorities over oral treatment. However, the greatest challenge for dermal delivery is the stratum corneum which is considered an effective barrier for penetration of most antifungal drugs into deeper skin layers. Terconazole (Tr), which is the first marketed triazole antifungal, was reported to be one of the most active azoles against vaginal candidiasis. Nevertheless, our work group is the first to investigate the potential of Tr in the treatment of skin mycosis via integration into lecithin microemulsion-based lipogels (LMBGs). The microemulsion regions of the investigated systems were detected through ternary phase diagrams. The in vitro characterization studies revealed promising physicochemical merits for the selected LMBGs as well as satisfactory in vitro antifungal activity. The current research work was endeavored to investigate the potential of such novel Tr-loaded LMBGs in comparison with conventional gels. Ex vivo permeation and retention studies in addition to in vivo deposition study showed a significant improvement in the permeability of Tr through animal skin from LMBGs compared to other conventional gels. Furthermore, the optimized microemulsion lipogel proved to be safe and a nonirritant to experimental animals through the acute sensitivity study and histological skin examination. Overall, lecithin-based microemulsion lipogels of different composition confirmed their potential as interesting nanocarriers for skin delivery of terconazole compared to current therapy.

Degradation of triadimefon and residue levels of metabolite triadimenol: tracing rapeseed from harvesting and storage to household oil processing.

BACKGROUND: Triadimefon is a fungicide used in agriculture to control fungal diseases such as sclerotinia sclerotiorum. RESULTS: In field trials, rape plants were sprayed with triadimefon at three different dosages during the flowering period. The degradation of triadimefon and the residue levels of its metabolite, triadimenol, in rapeseed obtained from harvesting, storage, and household oil processing were traced and evaluated. The pesticides were determined by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) at each processing step. Triadimefon degraded completely and only its metabolite, triadimenol, was detected in rapeseed after harvesting. The stability of triadimenol in rapeseed was studied at weekly storage intervals, from 0 to 7 weeks at ambient temperature (25 °C) and freezing temperature (-20 °C), respectively. Storage temperature had an important influence on the residue levels of triadimenol. The processing factor (PF) was defined as the ratio of pesticide residue levels in rapeseed to rapeseed oil levels during household oil processing. The average PF of triadimenol was about 0.96 for a hot pressing technique and 0.88 for a cold pressing technique. CONCLUSION: Different storage conditions and food processing could reduce the pesticide level to a greater or lesser extent. However, it is not easy to eliminate or significantly weaken triadimenol once triadimefon has degraded completely. © 2018 Society of Chemical Industry.

Isavuconazole: A new broad-spectrum azole. Part 2: pharmacokinetics and clinical activity.

Isavuconazole, the active moiety of its prodrug isavuconazonium, is a new extended-spectrum triazole whose activity against yeasts, molds, including Aspergillus and mucorales, and dimorphic fungi has been shown in vitro and in preclinical models. The most relevant pharmacokinetics features are water-solubility of the prodrug, rapid cleavage of the prodrug into active moiety and cleavage product by plasmatic esterases, high oral bioavailability of isavuconazole with an extensive penetration into most tissues and a good safety profile even in case of renal impairment. The results of two main clinical studies have led to an approval by FDA and EMA in the treatment of invasive aspergillosis and invasive mucormycosis. Isavuconazole is non-inferior to voriconazole in terms of response and survival in invasive aspergillosis and has shown improved safety and tolerability. Importantly, less hepatobiliary, skin and eye disorders have been reported in isavuconazole-treated patients. Isavuconazole has therefore been granted a grade A-I recommendation by the European Conference on Infections in Leukemia (ECIL) for the treatment of invasive aspergillosis. Efficacy has also been demonstrated in mucormycosis in an open-label study. Survival was similar to the survival of matched patients from the international Fungiscope registry and treated with an amphotericin B formulation. Isavuconazole failed to show non-inferiority to caspofungin in a large double-blind candidemia trial. The aim of this review is to give the reader an overview of the data available so far to support inclusion of isavuconazole in the anti-mold therapeutic arsenal.

Evaluation of a novel test design to determine uptake of chemicals by plant roots.

A new hydroponic study design to determine uptake of chemicals by plant roots was tested by (i) investigating uptake of [14C]-1,2,4-triazole by wheat plants in a ring test with ten laboratory organizations and (ii) studying uptake of ten other radiolabelled chemicals by potato, tomato or wheat plants in two laboratories. Replicate data from the ring test were used to calculate plant uptake factor (PUF) values (uptake into roots and shoots) and transpiration stream concentration factor (TSCF) values (uptake into shoots). Average PUF for 1,2,4-triazole was 0.73 (n=39, 95% confidence interval (CI): 0.64, 0.82) and the corresponding TSCF value was 1.03 (n=49, 95% CI: 0.76, 1.3). Boxplots and subsequent classification tree analysis of PUF and TSCF values showed that potential outlier values were >1.38 and were observed for PUF replicates with low biomass increase (ratio of final to initial biomass ≤1.739) and small initial biomass (≤1.55g) and for TSCF replicates with an increase in biomass of <0.67g over a period of eight days. Considering only valid replicate data, average values of PUF and TSCF were 0.65 (n=33, 95% CI: 0.57, 0.73) and 0.64 (n=39, 95% CI: 0.58, 0.70). The additional experiments with ten chemicals and three plant species showed that uptake was low for polar substances of high molecular weight (≥394g/mol) and that TSCF values increased with log Kow values of the tested chemicals ranging from -1.54 to 1.88 (polynomial equation with R2=0.64). A cluster analysis for three of the compounds that were tested on wheat and tomato indicated that the plant uptake was mainly determined by the substance. Overall, the findings show that the hydroponic study design allows for reliable quantification of plant uptake over a range of compound/crop combinations.

The evaluation of acute toxicity, antimicrobial activity of 1-phenyl-5-p-tolyl-1H-1, 2, 3-triazole, and binding to human serum albumin.

1-Phenyl-5-p-tolyl-1H-1, 2, 3-triazole (PPTA) was a synthesized compound. The result of acute toxicities to mice of PPTA by intragastric administration indicated that PPTA did not produce any significant acute toxic effect on Kunming strain mice. It exhibited the various potent inhibitory activities against two kinds of bananas pathogenic bacteria, black sigatoka and freckle, when compared with that of control drugs and the inhibitory rates were up to 64.14% and 43.46%, respectively, with the same concentration of 7.06 mM. The interaction of PPTA with human serum albumin (HSA) was studied using fluorescence polarization, absorption spectra, 3D fluorescence, and synchronous spectra in combination with quantum chemistry and molecular modeling. Multiple modes of interaction between PPTA and HSA were suggested to stabilize the PPTA-HSA complex, based on thermodynamic data and molecular modeling. Binding of PPTA to HSA induced perturbation in the microenvironment around HSA as well as secondary structural changes in the protein.

Bromodomain and extraterminal (BET) proteins regulate biliary-driven liver regeneration.

BACKGROUND & AIMS: During liver regeneration, hepatocytes are derived from pre-existing hepatocytes. However, if hepatocyte proliferation is compromised, biliary epithelial cells (BECs) become the source of new hepatocytes. We recently reported on a zebrafish liver regeneration model in which BECs extensively contribute to hepatocytes. Using this model, we performed a targeted chemical screen to identify important factors that regulate BEC-driven liver regeneration, the mechanisms of which remain largely unknown. METHODS: Using Tg(fabp10a:CFP-NTR) zebrafish, we examined the effects of 44 selected compounds on BEC-driven liver regeneration. Liver size was assessed by fabp10a:DsRed expression; liver marker expression was analyzed by immunostaining, in situ hybridization and quantitative PCR. Proliferation and apoptosis were also examined. Moreover, we used a mouse liver injury model, choline-deficient, ethionine-supplemented (CDE) diet. RESULTS: We identified 10 compounds that affected regenerating liver size. Among them, only bromodomain and extraterminal domain (BET) inhibitors, JQ1 and iBET151, blocked both Prox1 and Hnf4a induction in BECs. BET inhibition during hepatocyte ablation blocked BEC dedifferentiation into hepatoblast-like cells (HB-LCs). Intriguingly, after JQ1 washout, liver regeneration resumed, indicating temporal, but not permanent, perturbation of liver regeneration by BET inhibition. BET inhibition after hepatocyte ablation suppressed the proliferation of newly generated hepatocytes and delayed hepatocyte maturation. Importantly, Myca overexpression, in part, rescued the proliferation defect. Furthermore, oval cell numbers in mice fed CDE diet were greatly reduced upon JQ1 administration, supporting the zebrafish findings. CONCLUSIONS: BET proteins regulate BEC-driven liver regeneration at multiple steps: BEC dedifferentiation, HB-LC proliferation, the proliferation of newly generated hepatocytes, and hepatocyte maturation.

Identification and optimisation of a series of tetrahydrobenzotriazoles as metabotropic glutamate receptor 5-selective positive allosteric modulators that improve performance in a preclinical model of cognition.

Herein we describe a series of tetrahydrobenzotriazoles as novel, potent metabotropic glutamate receptor subtype 5 (mGlu5) positive allosteric modulators (PAMs). Exploration of the SAR surrounding the tetrahydrobenzotriazole core ultimately led to the identification of 29 as a potent mGlu5 PAM with a low maximal glutamate potency fold shift, acceptable in vitro DMPK parameters and in vivo PK profile and efficacy in the rat novel object recognition (NOR) assay. As a result 29 was identified as a suitable compound for progression to in vivo safety evaluation.

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 1 mL. The analytes of six enantiomers were analyzed on Chiralpak IA-3 column (150 × 4.6 mm) 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 4 min at a flow rate of 2 mL/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 50 µg/kg levels. The limits of quantification were 0.5 µg/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.

Dissipation of the fungicide hexaconazole in oil palm plantation.

Hexaconazole is a potential fungicide to be used in the oil palm plantation for controlling the basal stem root (BSR) disease caused by Ganoderma boninense. Therefore, the dissipation rate of hexaconazole in an oil palm agroecosystem under field conditions was studied. Two experimental plots were treated with hexaconazole at the recommended dosage of 4.5 g a.i. palm(-1) (active ingredient) and at double the recommended dosage (9.0 g a.i. palm(-1)), whilst one plot was untreated as control. The residue of hexaconazole was detected in soil samples in the range of 2.74 to 0.78 and 7.13 to 1.66 mg kg(-1) at the recommended and double recommended dosage plots, respectively. An initial relatively rapid dissipation rate of hexaconazole residues occurred but reduced with time. The dissipation of hexaconazole in soil was described using first-order kinetics with the value of coefficient regression (r (2) > 0.8). The results indicated that hexaconazole has moderate persistence in the soil and the half-life was found to be 69.3 and 86.6 days in the recommended and double recommended dosage plot, respectively. The results obtained highlight that downward movement of hexaconazole was led by preferential flow as shown in image analysis. It can be concluded that varying soil conditions, environmental factors, and pesticide chemical properties of hexaconazole has a significant impact on dissipation of hexaconazole in soil under humid conditions.

Synergistic intracellular iron chelation combinations: mechanisms and conditions for optimizing iron mobilization.

Iron chelators are increasingly combined clinically but the optimal conditions for cellular iron mobilization and mechanisms of interaction are unclear. Speciation plots for iron(III) binding of paired combinations of the licensed iron chelators desferrioxamine (DFO), deferiprone (DFP) and deferasirox (DFX) suggest conditions under which chelators can combine as 'shuttle' and 'sink' molecules but this approach does not consider their relative access and interaction with cellular iron pools. To address this issue, a sensitive ferrozine-based detection system for intracellular iron removal from the human hepatocyte cell line (HuH-7) was developed. Antagonism, synergism or additivity with paired chelator combinations was distinguished using mathematical isobologram analysis over clinically relevant chelator concentrations. All combinations showed synergistic iron mobilization at 8 h with clinically achievable concentrations of sink and shuttle chelators. Greatest synergism was achieved by combining DFP with DFX, where about 60% of mobilized iron was attributable to synergistic interaction. These findings predict that the DFX dose required for a half-maximum effect can be reduced by 3·8-fold when only 1 µmol/l DFP is added. Mechanisms for the synergy are suggested by consideration of the iron-chelate speciation plots together with the size, charge and lipid solubilities for each chelator. Hydroxypyridinones with low lipid solubilities but otherwise similar properties to DFP were used to interrogate the mechanistic interactions of chelator pairs. These studies confirm that synergistic cellular iron mobilization requires one chelator to have the physicochemical properties to enter cells, chelate intracellular iron and subsequently donate iron to a second 'sink' chelator.

Estrogens and their precursors in postmenopausal women with early breast cancer receiving anastrozole.

PURPOSE: We determined hormone concentrations (estradiol [E2], estrone [E1], estrone conjugates [E1-C], androstenedione [A], testosterone [T]) before and on anastrozole therapy where we also determined plasma concentrations of anastrozole and its metabolites. EXPERIMENTAL: Postmenopausal women who were to receive adjuvant anastrozole for resected early breast cancer were studied. Pretreatment, blood samples were obtained for the acquisition of DNA and for plasma hormone measurements (E2, E1, E1-C, A, and T). A second blood draw was obtained at least 4 weeks after starting anastrozole for hormone, anastrozole and metabolite measurements. For hormone assays, a validated bioanalytical method using gas chromatography negative ionization tandem mass spectrometry was used. Anastrozole and metabolite assays involved extraction of plasma followed by LC/MS/MS assays. RESULTS: 649 patients were evaluable. Pretreatment and during anastrozole, there was large inter-individual variability in E2, E1, and E1-C as well as anastrozole and anastrozole metabolite concentrations. E2 and E1 concentrations were below the lower limits of quantitation in 79% and 70%, respectively, of patients on anastrozole therapy, but those with reliable concentrations had a broad range (0.627-234.0 pg/mL, 1.562-183.2 pg/mL, respectively). Considering E2, 8.9% had the same or higher concentration relative to baseline while on anastrozole, documented by the presence of drug. CONCLUSIONS: We demonstrated large inter-individual variability in anastrozole and anastrozole metabolite concentrations as well as E1, E2, E1-C, A, and T concentrations before and while on anastrozole. These findings suggest that the standard 1mg daily dose of anastrozole is not optimal for a substantial proportion of women with breast cancer.

Physiological effects of temperature on turfgrass tolerance to amicarbazone.

BACKGROUND: Amicarbazone effectively controls annual bluegrass (Poa annua L.) in bermudagrass [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt-Davy] and tall fescue (Festuca arundinacea Schreb.) with spring applications, but summer applications may excessively injure tall fescue. The objective of this research was to investigate physiological effects of temperature on amicarbazone efficacy, absorption, translocation and metabolism in annual bluegrass, bermudagrass and tall fescue. RESULTS: At 25/20 °C (day/night), annual bluegrass absorbed 58 and 40% more foliar-applied amicarbazone than bermudagrass and tall fescue, respectively, after 72 h. Foliar absorption increased at 40/35 °C in all species, compared with 25/20 °C, and tall fescue had similar absorption to annual bluegrass at 40/35 °C. At 6 days after treatment, annual bluegrass metabolized 54% of foliar-applied amicarbazone, while bermudagrass and tall fescue metabolized 67 and 64% respectively. CONCLUSION: Tall fescue is more tolerant to amicarbazone than annual bluegrass at moderate temperatures (≈25/20 °C) owing to less absorption and greater metabolism. However, tall fescue susceptibility to amicarbazone injury at high temperatures (40/35 °C) results from enhanced herbicide absorption compared with lower temperatures (25/20 °C). Bermudagrass is more tolerant to amicarbazone than annual bluegrass and tall fescue owing to less herbicide absorption, regardless of temperature.

Persistence and dissipation kinetics of trifloxystrobin and tebuconazole in onion and soil.

The persistence and dissipation kinetics of trifloxystrobin and tebuconazole on onion were studied after application of their combination formulation at a standard and double dose of 75 + 150 and 150 + 300 g a.i. ha(-1). The fungicides were extracted with acetone, cleaned-up using activated charcoal (trifloxystrobin) and neutral alumina (tebuconazole). Analysis was carried out by gas chromatograph (GC) and confirmed by gas chromatograph mass spectrometry (GC-MS). The recovery was above 80% and limit of quantification (LOQ) 0.05 mg kg(-1) for both fungicides. Initial residue deposits of trifloxystrobin were 0.68 and 1.01 mg kg(-1) and tebuconazole 0.673 and 1.95 mg kg(-1) from standard and double dose treatments, respectively. Dissipation of the fungicides followed first-order kinetics and the half life of degradation was 6-6.6 days. Matured onion bulb (and field soil) harvested after 30 days was free from fungicide residues. These findings suggest recommended safe pre-harvest interval (PHI) of 14 and 25 days for spring onion consumption after treatment of Nativo 75 WG at the standard and double doses, respectively. Matured onion bulbs at harvest were free from fungicide residues.

Pharmacokinetics of posaconazole within epithelial cells and fungi: insights into potential mechanisms of action during treatment and prophylaxis.

BACKGROUND: The antifungal posaconazole concentrates within host cells and protects against Aspergillus fumigatus. The specific subcellular location of posaconazole and the mechanism by which cell-associated posaconazole inhibits fungal growth remain uncharacterized. METHODS: Posaconazole was conjugated with the fluorophore boron-dipyrromethene (BDP-PCZ). A549 pulmonary epithelial cells and A. fumigatus were exposed to BDP-PCZ individually and in coculture. BDP-PCZ subcellular localization and trafficking were observed using confocal microscopy and flow cytometry. RESULTS: BDP-PCZ concentrated within A549 cell membranes, and in particular within the endoplasmic reticulum. Epithelial cell-associated BDP-PCZ rapidly transferred to and concentrated within A. fumigatus cell membranes on contact. BDP-PCZ transfer to conidia did not require phagocytosis and was markedly enhanced by the conidial hydrophobin RodA. Within AF, BDP-PCZ also concentrated in membranes including the endoplasmic reticulum and colocalized with the azole target enzyme CYP51a. Concentration of BDP-PCZ within host and fungal cell membranes persisted for >48 hours and could be competitively inhibited by posaconazole but not voriconazole. CONCLUSIONS: Posaconazole concentrates within host cell membranes and rapidly transfers to A. fumigatus, where it accumulates to high concentrations and persists at the site of its target enzyme. These intracellular and intercellular pharmacokinetic properties probably contribute to the efficacy of PCZ.

Fragment-based discovery of novel and selective mPGES-1 inhibitors Part 1: identification of sulfonamido-1,2,3-triazole-4,5-dicarboxylic acid.

Microsomal prostaglandin E synthase-1 (mPGES-1) is an inducible prostaglandin E synthase that catalyzes the conversion of prostaglandin PGH(2) to PGE(2) and represents a novel target for therapeutic treatment of inflammatory disorders. It is essential to identify mPGES-1 inhibitor with novel scaffold as new hit or lead compound for the purpose of the next-generation anti-inflammatory drugs. Herein we report the discovery of sulfonamido-1,2,3-triazole-4,5-dicarboxylic derivatives as a novel class of mPGES-1 inhibitors identified through fragment-based virtual screening and in vitro assays on the inhibitory activity of the actual compounds. 1-[2-(N-Phenylbenzenesulfonamido)ethyl]-1H-1,2,3-triazole-4,5-dicarboxylic acid (6f) inhibits human mPGES-1 (IC(50) of 1.1 µM) with high selectivity (ca.1000-fold) over both COX-1 and COX-2 in a cell-free assay. In addition, the activity of compound 6f was again tested at 10 µM concentration in presence of 0.1% Triton X-100 and found to be reduced to 1/4 of its original activity without this detergent. Compared to the complete loss of activity of nuisance inhibitor with the detergent, therefore, compound 6f would be regarded as a partial nuisance inhibitor of mPGES-1 with a novel scaffold for the optimal design of more potent mPGES-1 inhibitors.