Radiosynthesis of a carbon-11-labeled AMPAR allosteric modulator as a new PET radioligand candidate for imaging of Alzheimer's disease

To develop PET tracers for imaging of Alzheimer's disease, a new carbon-11-labeled AMPAR allosteric modulator 4-cyclopropyl-7-(3-[¹¹C]methoxyphenoxy)-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide ([¹¹C]8) has been synthesized. The reference standard 4-cyclopropyl-7-(3-methoxyphenoxy)-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide (8) and its corresponding desmethylated precursor 4-cyclopropyl-7-(3-hydroxyphenoxy)-3,4-dihydro-2H-benzo[e][1,2,4]thiadiazine 1,1-dioxide (9) were synthesized from 4-methoxyabiline and chlorosulfonyl isocyanate in eight and nine steps with 3% and 1% overall chemical yield, respectively. The target tracer [¹¹C]8 was prepared from the precursor 9 with [¹¹C]CH₃OTf through O-[¹¹C]methylation and isolated by HPLC combined with SPE in 10-15% radiochemical yield, based on [¹¹C]CO₂ and decay corrected to end of bombardment (EOB). The radiochemical purity was >99%, and the molar activity (A_M) at EOB was 370-740 GBq/μmol with a total synthesis time of 35-40-minutes from EOB.

Environmental Factors and Soil Amendment Affect the Decomposition Rate of Dazomet Fumigant

Dazomet (3,5-dimethyl-1,3,5-thiadiazinane-2-thione) is widely used as a soil fumigant for controlling soil-borne diseases and pests in China and other agricultural countries. The active ingredient of dazomet is its degradation product, methyl isothiocyanate. Little is known about the environmental conditions that affect the degradation of dazomet in soil. In this study, we conducted laboratory incubation experiments to test the effects of several environmental factors, including soil texture, water content, temperature, pH, and soil amendments, such as chicken manure or urea fertilizer, on the decomposition of dazomet. Results showed that dazomet degradation in soil is an abiotic process strongly dependent on soil texture, water content, temperature, and pH. Decomposition rates differed greatly in various soils, depending mainly on soil physicochemical properties such as pH and organic matter content. The degradation rate increased by 15 to 24 times and by 16 to 37 times when soil temperature increased from 5 to 45°C, and water content increased from 10 to 30%, respectively. Dazomet degraded faster in alkaline versus acidic soil. Both chicken manure and urea fertilizer moderately slowed dazomet degradation. Dazomet was degraded in soil mainly by hydrolysis. The results of our study contribute to a better understanding of the environmental behavior of dazomet, potentially leading to its more efficient, safe, profitable, and effective use by farmers.

Ecotoxicity of 1,3-dichloropropene, metam sodium, and dazomet on the earthworm Eisenia fetida with modified artificial soil test and natural soil test

1,3-Dichloropropene (1,3-D), metam sodium (MS), and dazomet (DZ) are widely used as preplant soil fumigants to solve soilborne problems. To provide a more scientific and accurate evaluation of 1,3-D, MS, and DZ toxicity to the earthworm Eisenia fetida, modified artificial soil test and natural soil test were studied. The suitable soil moisture to maintain over 90% survival of the earthworms after 4 weeks of treatment in an enclosed system for modified artificial soil test and natural soil test were 26.9 to 86.4% of water-holding capacity (WHC) and 66.2 to 84.3% of WHC, respectively. The optimal soil moisture levels for modified artificial soil test and natural soil test (75 and 55% of WHC, respectively) were finally used to evaluate the toxicity of 1,3-D, MS, and DZ on earthworms. Each desiccator with 10 earthworms and natural or artificial soil was stored at 20 ± 1 °C under constant light of 400 to 800 lx for 2 weeks. The modified artificial soil test showed LC₅₀ values for 1,3-D, MS, and DZ of 3.60, 1.69, and 5.41 mg a.i. kg^-1 soil, respectively. The modified natural soil test of the fumigants showed similar LC₅₀ values of 2.77 and 0.65 mg a.i. kg^-1 soil, except for DZ at 0.98 mg a.i. kg^-1 soil. The present study confirms that both modified artificial soil test and modified natural soil test offer standard methods for acute toxicity test of 1,3-D, MS, and DZ on the earthworms and scientific evidences for assessing the effects of soil fumigants on non-target organisms in the soils. Graphical Abstract Two novel acute toxicity test methods for soil fumigants on the earthworm Eisenia fetida.

Dissipation kinetics of pre-plant pesticides in greenhouse-devoted soils

This work was conducted to study the distribution of methyl isothiocyanate (MITC) in greenhouse soils treated with the fumigant dazomet (DZ) from the formulated product "Basamid Granular(®)", but also of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) from the fumigant "Agrocelhone NE(®)". In order to achieve this aim, several methods for the determination of fumigants residues in soils, but also pepper fruits were optimized and characterized. With independence of the soil depth, no residues of MITC, 1,3-D and CP above the detection limits were observed in soils covered with a polyethylene (PE) film (0.04 mm thick) after 27, 13 and 8 days of treatment, respectively. Liberation and dissipation curves of MITC in soil in presence of a PE film (0.04 mm) used to limit volatilization losses were also obtained. According to the results, the rate of decomposition of DZ into MITC have a half-life of 3.7 days in the surface horizon (5-10 cm) of the soil while in the subsurface horizon (15-20 cm), MITC formation rate is slightly slow (half-life of 3.2 days). With respect to the dissipation process, half-lives lower than 1 day were obtained for both depths (0.8 and 0.9 for the surface and the subsurface horizon, respectively). In the case of 1,3-D and CP in soil, the dissipation half-life of 1,3-D on soils was a bit higher than for CP (2 days vs. 1). In addition, the presence of residues of the fumigants on green pepper fruits grown on the treated soils was not detected as expected.

[The estimation of the perspectives of the 1,3,4-thiadiazine derivatives as the protectors means for the health tissues under radiation therapy of malignant tumour patients]

We generalized the results of our own researches of the mechanisms, determined the high (90% BALB-line mice were survived) radioprotection activity by 1,3,4-thiadiazine derivatives. It was determined that this preparat achieves the highest concentrations in the critical for the acute radiation influence tissues. The preparate bind with the cell's membranes, nucleus and mitochondries, blockade the development of the radial reactions on the tissues level. Small quantity passes to the brain marrow, takes part in the regulative processes, which central nervous system is produced, reduces the metabolitical processes in the organism. It doesn't possess the election accumulation in the tumour and it is perspective for the prevention of damage health tissues under irradiation cancroid's therapy.

FI-chemiluminometric study of thiazides by on-line photochemical reaction

The present manuscript deals with a simple and sensitive flow-injection method for the chemiluminescent determination of thiazides. The method is based on the on-line photodegradation and chemiluminescent determination of the resulting photo-fragments. The on-line photodegradation is performed in basic medium by using a photoreactor consisting of a 550cm long x 0.8mm ID piece of PTFE tubing helically coiled around an 8W low-pressure mercury lamp. The determination of the photo-irradiated thiazides is performed by a chemiluminescent oxidative reaction with Ce(IV) in sulphuric acid medium. A heterogeneous group of thiazides (indapamide, metolazone, hydroflumethiazide, chlorthalidone and bendroflumethiazide) has been studied. Hydrochlorothiazide was selected as a test substance. The "on-line" photochemical reaction approach allows the sensitive chemiluminescent determination of thiazides which do not present native chemiluminescence in the absence of sensitizers such as Rhodamine 6G. Linear calibration graphs were typically over the range 0.5-12 microgml(-1) (indapamide, metolazone, hydroflumethiazide and chlorthalidone); and over the range 0.5-5 microgml(-1) (hydrochlorothiazide). Limits of detection ranged between 0.005 microgml(-1) (hydrochlorothiazide) and 0.06 microgml(-1) (bendroflumethiazide). The relative standard deviation for the test substance was 2.0% for 2 microgl(-1) of the drug (n = 11) and the throughput was 65 h(-1) in all cases. The assessment of the photodegradation step on the molecular structure of thiazides was established by recording UV and fluorimetric spectra. The viability of the on-line photoinduced fluorescent determination of hydroflumethiazide and bendroflumethiazide was confirmed. The method was also applied to the determination of hydrochlorothiazide in commercially available formulation.

[Determination of buprofezin, methamidophos, acephate, and triazophos residues in Chinese tea samples by gas chromatography]

A method has been developed for the simultaneous determination of buprofezin, methamidophos, acephate and triazophos residues in Chinese tea samples. The pesticide residues were extracted from tea samples with a mixture of ethyl acetate and n-hexane (50:50, v/v) at 45 degrees C. The extracts were subsequently treated with a column packed with 40 mg of active carbon by gradient elution with ethyl acetate and n-hexane. Buprofenzin and the three organophosphorus pesticides were analyzed by gas chromatography using a DB-210 capillary column and a nitrogen-phosphorus detector. The recoveries for spiked standards were 73.4%-96.9%. The relative standard deviations were all within 4.63%. The limits of quantitation (3sigma) in the tea samples were about 7.0-12.0 microg/kg.

[Effects of rice cleaning and cooking process on the residues of flutolanil, fenobucarb, silafluofen and buprofezin in rice]

We studied the effect of cleaning and cooking on the residues of flutolanil, fenobucarb, silafluofen and buprofezin in rice. The rice had been sprayed in a paddy field in Wakayama city, with 3 kinds of pesticide application protocols: spraying once at the usual concentration of pesticides, repeated spraying (3 times) with the usual concentration of pesticides and spraying once with 3 times the usual concentration of pesticides. The residue levels of pesticide decreased during the rice cleaning process. Silafluofen, which has a higher log Pow value, remained in the hull of the rice. Fenobucarb, which has a lower log Pow value, penetrated inside the rice. The residue concentration of pesticide in polished rice was higher than that in pre-washed rice processed ready for cooking. During the cooking procedure, the reduction of pesticides in polished rice was higher than that in brown rice.

Acephate and buprofezin residues in olives and olive oil

Field trials were carried out to study the persistence of acephate and buprofezin on olives. Two cultivars, pizz'e carroga and pendolino, with very large and small fruits respectively were used. After treatment, no difference was found between the two pesticide deposits on the olives. The disappearance rates, calculated as pseudo first order kinetics, were similar for both pesticides (on average 12 days). Methamidophos, the acephate metabolite, was always present on all olives, and in some pendolino samples it showed higher residues than the maximum residue limit (MRL). During washing, the first step of olive processing, the residue level of both pesticides on the olives did not decrease. After processing of the olives into oil, no residues of acephate or methamidophos were found in the olive oil, while the residues of buprofezin were on average four times higher than on olives.

[The technology for manufacturing antiparasitic preparations. 9. The new preparation tizanox and an evaluation of its anti-Hymenolepis activity]

The paper describes a procedure for manufacturing the new anthelminthic Tizanox. It shows it necessary to administer a larger dose of the drug than that of azinox (praziquantel) to treat experimental hymenolepiasis. However, the lower toxicity of Tizanox enhances its chemotherapeutical index.

Quantitation of taurolidine decomposition in polymer solutions by chromotropic acid formaldehyde assay method

A sensitive, selective, and specific assay was needed to study the degradation kinetics of taurolidine and its stabilization by polyvinylpyrrolidone (PVP). The purpose of the present study was to evaluate the usefulness of the chromotropic acid method and other formaldehyde or amine derivatization methods. The methods evaluated included formaldehyde derivatization with chromotropic acid, acetylacetone, 4-amino-5-hydrazino-3-mercapto-1,2,4-triazole, semicarbazide hydrochloride, or 2,4-dinitrophenylhydrazine and taurolidine decomposition product derivatization with dansylchloride or 7-chloro-4-nitrobenz-2-oxa-1,3-diazole chloride. Results indicated that the chromotropic acid method provided sufficient selectivity, reproducibility and sensitivity. It was able to quench taurultam decomposition and avoided PVP interference. The method was optimized by performance based selection of reagent lots, appropriate reagent storage and preparation, and controlled derivatization conditions. In conclusion, the optimized chromotropic method was the most appropriate method for quantitating taurolidine decomposition.

Synthesis and antifungal activities of some new tetrahydro-2H-1,3,5-thiadiazine-2-thiones

A number of new 3-benzyl-5-[alpha-(substituted)carboxymethyl]- tetrahydro-2H-1,3,5-thiadiazine-2-thiones has been synthesized as prodrugs by incorporating the amine group of some amino acids into tetrahydro-2-H-1,3,5-thiadiazine-2-thione ring. The compounds have been prepared by the reactions of benzylamine with potassium hydroxide, carbon disulphide formaldehyde and various amino acids. The structures of the compounds have been elucidated by UV, IR, 1H-NMR, mass spectra and elementary analysis. The in vitro activity of these compounds against yeast-like fungi (Candida albicans, C. parapsilosis, C. pseudotropicalis, C. stellatoidea) was investigated by tube dilution method. Their minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values were determined. All the compounds were found to be active between 3.12-12.5 micrograms/ml against the four fungi tested.

NMR studies and GC analysis of the antibacterial agent taurolidine

The NMR spectrum of taurolidine in deuterium oxide was compared with spectra obtained from model experiments with amines and formaldehyde. Head-space analysis combined with capillary GC showed that there was less than 0.004% free formaldehyde present in 2% solutions of taurolidine. This value is comparable to the concentration of formaldehyde found when the taurolidine solutions were injected directly onto GC columns.