Control of nitrification of fertilizer nitrogen: Effect of inhibitors,banding and nesting

Laboratory incubation and field experiments were conducted to evaluate thiourea, ATC (4-amino-1, 2, 4 triazole hydrochloride) and N-Serve 24 E (2-chloro-6-trichloromethyl-pyridine) as inhibitors of nitrification of fertilizer N. In the incubation experiment, most of the added aqueous NH₃ or urea was nitrified at 14 days on both soils, but addition of the inhibitors to fertilizer N decreased the conversion of NH₄−N to NO₃−N markedly. There was less nitrification for ATC and thiourea but not for N-Serve 24 E when the fertilizers and the inhibitors were placed at a point as opposed to when mixed into soil. After 28 days, ATC and N-Serve 24 E were more effective in inhibiting nitrification than thiourea. ATC and N-Serve 24 E also inhibited release of mineral N (NH₄−N+NO₃−N) from native soil N. In the uncropped field experiment, which received N fertilizers in the fall, nitrification of fall-applied N placed in the 15-cm bands was almost complete by early May in the Malmo soil, but not in the Breton soil. When ATC or thiourea had been applied with urea, nitrification of fall-applied N was depressed by May and the recovery of applied N as NH₄−N was greater with increasing band spacing to 60 cm or placing N fertilizer in nests (a method of application where urea prills were placed at a point in the soil in the center of 60×60 cm area). In late June, the percentage recovery of fall-applied N in soil as NH₄−N or mineral N increased with wide band spacing, or nest placement, or by adding ATC to fertilizer N on both soils. These results indicate that placing ammonium-based N fertilizers in widely-spaced bands or in nests with low rates of inhibitors slows nitrification enough to prevent much of the losses from fall-applied N. Scientific Paper No. 552, Lacombe Research Station, Research Branch, Agric, Can.     

Design,in Silico Studies and Biological Evaluation of New Chiral Thiourea and 1,3-Thiazolidine-4,5-dione Derivatives

In this study, new chiral thiourea and 1,3-thiazolidine-4,5-dione derivatives were synthesized, it was aimed to evaluate the various biological activities and molecular docking of these compounds. Firstly, the new thioureas ( 1 – 16 ) were obtained by reacting 1-naphthylisothiocyanate with different chiral amines. Then, the chiral thioureas were cyclized with oxalyl chloride to obtain 1,3-thiazolidine-4,5-dione derivatives ( 17 – 32 ). All compounds were evaluated with several in vitro antioxidant and enzyme inhibition activities. Compound 30 was the most active compound against AChE, with a value of IC₅₀=8.09±0.58 μM. On the other hand, all compounds were tested in silico absorption, distribution, metabolism, and excretion (ADME) assays to better understand their bioavailability. These physicochemical properties, pharmacokinetics, and drug-likeness of all compounds were calculated using SwissADME. Furthermore, according to molecular docking analyses compound 30 exhibited significant binding affinities for all enzymes. Based on our overall observations, compound 30 could be recommended as a potential lead for the therapuetic of Alzheimer's.     

Effect of thiourea and substituted thioureas on dynein ATPase and on the turbidity response of tetrahymena cilia

The effects of thioura and of several substituted thioureas–phenylthiourea, α-naphtylthiourea, metiamide, and burimamide–on dynein ATPase have been studied. The substituted thioureas are over 30 times more potent than thiourea in causing enhancement of 30S dynein ATPase activity and inhibition of 14S dynein ATPase activity. The effects of thiourea and phenylthiourea can be prevented by very low concentrations of β-mercaptoethanol or dithiotheritol. Axonemal ATPase is also enhanced by the thioureas, but the reaction proceeds more slowly than for solubilized 30S dynein. Enhancement of 30S dynein ATPase by metiamide is prevented by low (～ 1 μM) concentrations of ATP and, less effectively, by AMP-PNP, but not by AMP-PCP even though the latter is a stronger inhibitor of 30S dynein ATPase than is AMP-PNP. The thioureas inhibit the ATP-induced decrease in turbidity (measured as ΔA₃₅₀) of axonemal suspensions. Inhibition of the turbidity response is also prevented by low concentrations of β-mercaptoethanol, but, in contrast to the irreversible enhancement of ATPase activity, inhibition of the turbidity response is largely reversible. The ability of 30S dynein to rebind onto twice extracted axonemes is not changed by treatment with phenylthiourea or metiamide. These observations indicate that the thioureas react with at least two sets of SH or S–S groups on axonemes. Reaction with the group(s) on the 30S dynein causes an apparently irreversible enhancement of ATPase activity. Reaction with another group(s) causes a reversible inhibition of the turbidity response.     

Molecular structure,spectroscopic (FT-IR,FT-Raman,UV–vis), NBO,thermochemistry analysis of bis(thiourea)zinc(II) chloride crystals

The experimental and theoretical studies on the molecular structure and vibrational spectra of bis(thiourea)zinc(II) chloride (BTZC) crystals were investigated. The Fourier transform infrared, Fourier transform Raman and UV–vis spectra of BTZC were recorded. The molecular geometry and vibrational frequencies of BTZC in the ground state were calculated by using B3LYP with LANL2DZ as basis set. Comparison of the observed structural parameters of BTZC with single-crystal X-ray studies yields a good agreement. Vibrational analysis of the simultaneous IR and Raman activation of the Zn–Cl stretching mode in the molecule provides the evidence for the charge transfer interaction taking place within the molecule. The energy and oscillator strength are calculated by time-dependent density functional theory. The simulated spectra satisfactorily coincide with the experimental spectra.     

Chemically modified siRNAs and miRNAs bearing urea/thiourea-bridged aromatic compounds at their 3′-end for RNAi therapy

We have developed chemically modified siRNAs and miRNAs bearing urea/thiourea-bridged aromatic compounds at their 3′-end for RNAi therapy. Chemically modified RNAs possessing urea/thiourea-bridged aromatic compounds instead of naturally occurring dinucleotides at the 3′-overhang region were easily prepared in good yields and were more resistant to nucleolytic hydrolysis than unmodified RNA. siRNAs containing urea or thiourea derivatives showed the desired knockdown effect. Furthermore, modified miR-143 duplexes carrying the urea/thiourea compounds in the 3′-end of each strand were able to inhibit the growth of human bladder cancer T24 cells.     

Exogenous application of mannitol and thiourea regulates plant growth and oxidative stress responses in salt-stressed maize (Zea mays L.)

Abstract

The mechanism of growth amelioration in salt-stressed maize (Zea mays L. cv., DK 647 F1) by exogenously applied mannitol (M) and thiourea (T) was investigated. Maize seedlings were planted in pots containing perlite and subjected to 0 or 100 mM NaCl in full strength Hoagland's nutrient solution. Two levels of M (15 and 30 mM) or T (3.5 and 7.0 mM) were sprayed to the leaves of maize seedlings 10 days after germination. Salinity stress caused considerable reduction in plant dry biomass, chlorophyll content, and relative water content in the maize plants. However, it increased the activities of catalase (CAT; EC 1.11.1.6), superoxide dismutase (SOD; EC 1.15.1.1), and polyphenol oxidase (PPO; EC 1.10.3.1), and levels of hydrogen peroxide (H₂O₂) and electrolyte leakage, but it did not change peroxidase (POD; EC 1.11.1.7) activity. Foliar application of M or T was found to be effective in checking salt-induced shoot growth inhibition. Exogenously applied M or T reduced the activities of CAT, SOD, POD, and PPO in the salt-treated maize plants compared to those in the plants not fed with these organic compounds. Salinity increased Na⁺ contents but decreased those of K⁺, Ca^{2 +}, and P in the leaves and roots of the maize plants. Foliar-applied M or T increased the contents of K⁺, Ca^{2 +}, and P, but decreased that of Na⁺ in the salt-stressed maize plants with respect to those of the salt-stressed plants not supplied with mannitol or thiourea. Mannitol was found to be more effective than thiourea in improving salinity tolerance of maize plants in terms of growth and physiological attributes measured in the present study.     

Organocatalytic enantioselective Michael addition of malononitrile to nitroolefins catalyzed by bifunctional thiourea

A novel enantioselective Michael addition of malononitrile to trans-β-nitroolefins in the presence of bifunctional amine thiourea organocatalyst is developed. The Michael reaction catalyzed by amine thioureas containing both central and axial chiral elements proceeded smoothly and provided the desired adducts with high yields (up to 96% yield) and moderate enantioselectivities (up to 83% enantiomeric excess).     

Synthesis, crystal structures and, antibacterial and antiproliferative activities in vitro of palladium(II) complexes of triphenylphosphine and thioamides

Palladium(II) complexes with triphenylphosphine (PPh₃) and thioamides of the general formulae, [Pd(L)₂(PPh₃)₂]Cl₂ and [Pd(L)₂(PPh₃)₂] have been prepared and characterized by elemental analysis, IR and NMR (¹H, ¹³C and ³¹P) methods, and two of them (trans-[Pd(PPh₃)₂(Dmtu)₂]Cl₂·(H₂O)(CH₃OH)_0.5 (1) and trans-[Pd(PPh₃)₂(Mpy)₂] (2)) by X-ray crystallography; where L = thiourea (Tu), methylthiourea (Metu), N,N′-dimethylthiourea (Dmtu), tetramethylthiourea (Tmtu), 2-mercaptopyridine (Mpy), 2-mercaptopyrimidine (Mpm) and thionicotinamide (Tna). The spectral data of the complexes are consistent with the sulfur coordination of thioamides to palladium(II). The crystal structures of the complexes show that (1) has ionic character consisting of [Pd(PPh₃)₂(Dmtu)₂]⁺² cations and uncoordinated Cl⁻ ions, while (2) is a neutral complex with Mpy behaving as anionic thiolate ligand. The coordination environment around palladium in (2) is nearly regular square-planar, while in (1) the trans angles show significant distortions from 180°. The complexes were screened for antibacterial effects, brine shrimps lethality bioassay and antitumor activity. These complexes showed significant activities in most of the cases against the tested bacteria as compared to that of a standard drug. Their antitumor activity against prostate cancer cells (PC3) is comparable with doxorubicin, together with no cytotoxic effects in brine shrimps lethality bioassay study.     

Synthesis of acyl thiourea derivatives of chitosan and their antimicrobial activities in vitro

Three different acyl thiourea derivatives of chitosan (CS) were synthesized and their structures were characterized by FT-IR spectroscopy and elemental analysis. The antimicrobial behaviors of CS and its derivatives against four species of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Sarcina) and four crop-threatening pathogenic fungi (Alternaria solani, Fusarium oxysporum f. sp. vasinfectum, Colletotrichum gloeosporioides (Penz.) Saec, and Phyllisticta zingiberi) were investigated. The results indicated that the antimicrobial activities of the acyl thiourea derivatives are much better than that of the parent CS. The minimum value of MIC and MBC of the derivatives against E. coli was 15.62 and 62.49 microg/mL, respectively. All of the acyl thiourea derivatives had a significant inhibitory effect on the fungi in concentrations of 50-500 microg/mL; the maximum inhibitory index was 66.67%. The antifungal activities of the chloracetyl thiourea derivatives of CS are noticeably higher than the acetyl and benzoyl thiourea derivatives. The degree of grafting of the acyl thiourea group in the derivatives was related to antifungal activity; higher substitution resulted in stronger antifungal activity.     

Synthesis of benzoylthiourea derivatives and analysis of their antibacterial performance against planktonic Staphylococcus aureus and its biofilms

Following the appearance of several antimicrobial agents to control the spread of infections, two major challenges have emerged: (i) the occurrence and blowout of multiresistant bacteria and the increase of chronic diseases and (ii) difficult-to-eradicate infections. In this study, we tested five benzoylthiourea derivatives for their ability to inhibit and stop bacterial growth and evaluated the possible influence of 1,2,4-triazolyl-benzoylthiourea derivative 4 on the formation and eradication of Staphylococcus aureus biofilms. Benzoylthiourea derivatives 4 , 6 , 10 , 11 and 13 were obtained in one or two steps with low cost and subjected to tests to identify their minimum inhibitory concentration (MIC) and minimum bactericidal concentration. In vitro tests were also performed to assess their effects on biofilm formation and in preformed biofilms and scanning electron microscopy was used to visualize the effects on biofilm formation. The 1,2,4-triazolyl-benzoylthiourea derivative 4 showed bacteriostatic activity against the S. aureus HU25 clinical strain with an MIC of 16 µg ml⁻¹, which is below the toxic concentration (at 2500 µg ml⁻¹, 62·25% of the cells remained viable). Compound 4 also effectively prevented biofilm formation at the three subinhibitory concentrations tested (1/2 MIC, 1/4 MIC and 1/8 MIC) as confirmed by scanning electron microscopy. For breakdown of formed biofilms, the main influence was at a subinhibitory concentration (1/2 MIC). These findings make compound 4 a strong candidate for studies on the development of new antimicrobial and antibiofilm agents.