thiourea and dicyandiamido

Successful structural transformations of bioactive compounds into newer skeletal structures by replacing the substructure with others, the features of which are not necessarily similar to but more or less drastically varied from the original one, were proposed to be called being made "bioanalogously" instead of "bioisoterically". Precedents of the bioanalogous replacements of substructures composed of the amide, urea, and related components with others were explored. Anilides, N-phenylureas, and N-phenylcarbamates are bioanalogous as herbicides and topical antiseptics. The bioanalogy can be expanded to include substructures containing ester as well as ether components when local anesthetics are considered together. The polar hydrogen-bonding groups such as (thio)urea, cyanoguanidine, and nitroethenediamine substructures found in histamine H2-receptor antagonists are also bioanalogous in various other bioactive compound series. The open-chain amides and the corresponding "carbonylogously" ring-closured dicarboximides are bioanalogous in agrochemicals and antiandrogens as well as in CNS (central nervous system)-active agents. Very often, similarities in the substructural transformation patterns are observed in various bioanalogous series regardless of differences in the pharmacological category. The observations could be used to predict newer generation structures from an ultimate lead structure.

Topics: Amides; Carbamates; Diamines; Guanidines; Molecular Structure; Structure-Activity Relationship; Thiourea; Urea

Nitrification inhibitors (NIs) such as dicyandiamide (DCD), 3,4-dimethylpyrazole phosphate (DMPP), and allylthiourea (AT) are commonly used to suppress ammonia oxidization at different time scales varying from a few hours to several months. Although the responses of NIs to edaphic and temperature conditions have been studied, the influence of the aforementioned factors on their inhibitory effect remains unknown. In this study, laboratory-scale experiments were conducted to assess the short-term (24 h) influence of eight abiotic and biotic factors on the inhibitory effects of DCD, DMPP, and AT across six cropped and non-cropped soils at two temperature conditions with three covariates of soil texture. Simultaneously, the dominant contributions of ammonia-oxidizing archaea (AOA) and bacteria (AOB) to potential ammonia oxidization (PAO) were distinguished using the specific inhibitor 2 phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO). Our results revealed that AT demonstrated a considerably greater inhibitory effect (up to 94.9% for an application rate of 75 mg of NI/kg of dry soil) than DCD and DMPP. The inhibitory effect of AT was considerably affected by the relative proportions of silt, sand, and clay in the soil and total PAO. In contrast to previous studies, the inhibitory effects of all three NIs remained largely unaffected by the landcover type and temperature conditions for the incubation period of 24 h. Furthermore, the efficacy of all three tested NIs was not affected by the differential contributions of AOA and AOB to PAO. Collectively, our results suggested a limited influence of temperature on the inhibitory effects of all three NIs but a moderate dependence of AT on the soil texture and PAO. Our findings can enhance the estimation of the inhibitory effect in soil, and pure cultures targeting the AOA and AOB supported ammonia oxidization and, hence, nitrogen dynamics under NI applications.

Topics: Ammonia; Guanidines; Nitrification; Oxidation-Reduction; Phosphates; Pyrazoles; Soil; Soil Microbiology; Thiourea

In this study, the photocatalytic activity of graphitic carbon nitride (g-C

Topics: Anti-Bacterial Agents; Catalysis; Graphite; Guanidines; Ions; Metals, Heavy; Nitriles; Photochemical Processes; Thiourea; Urea; Water Pollutants, Chemical; Water Purification

Topics: Ammonia; Ampicillin; Archaea; Betaproteobacteria; Gene Dosage; Geologic Sediments; Guanidines; High-Throughput Nucleotide Sequencing; Nitrosomonas; Oxidation-Reduction; Phylogeny; Rivers; Smell; Thiourea

This study investigated whether applying dicyandiamide (DCD) and guanyl thiourea (GTU) in conjunction with urea improves the efficacy of nitrification inhibition relative to traditional fertiliser application of urea or urea + DCD. Urea at a rate of 100 mg N kg(-1) soil was applied to soil microcosms (high nutrient tenosol and low nutrient hydrosol) which were treated with either no inhibitor (urea-only); 15 mg DCD kg(-1) soil or 15 mg DCD kg(-1) soil plus 21 mg GTU kg soil(-1). Mineral N (NH4(+) & NO3(-)) concentrations, potential nitrification rates (PNR) and abundances of ammonia oxidising bacteria (AOB) were measured over time. After 100-days incubation, ∼73 mg N kg(-1) soil was found as NH4(+) when urea + DCD + GTU were applied to the tenosol. NH4(+) concentrations were lower (11-32 mg N kg(-1) soil) when urea or urea + DCD were applied. This suggests that the application of GTU in conjunction with DCD elongated the effects of nitrification inhibition. In both soils, PNRs were faster and AOB abundances (gene copies g(-1) soil) were higher when urea was applied without nitrification inhibitors. There were, however, no differences in PNR or AOB abundances in either soil type when 'urea + DCD' or 'urea + DCD + GTU' were applied. The results indicate that the application of GTU with DCD may extend nitrification inhibition in certain soil types. This finding has the potential to improve the efficacy of commercially available and widely used inhibitors such as DCD.

Topics: Ammonia; Archaea; Bacteria; Bacterial Physiological Phenomena; Drug Combinations; Fertilizers; Guanidines; Nitrification; Nitrogen; Oxidation-Reduction; Soil; Soil Microbiology; Thiourea

Nitrification inhibitors have been used for decades to improve nitrogen fertilizer utilization in farmland. However, their effect on ammonia-oxidizing Archaea (AOA) in soil is little explored. Here, we compared the impact of diverse inhibitors on nitrification activity of the soil archaeon Ca. Nitrososphaera viennensis EN76 and compared it to that of the ammonia-oxidizing bacterium (AOB) Nitrosospira multiformis. Allylthiourea, amidinothiourea, and dicyandiamide (DCD) inhibited ammonia oxidation in cultures of both N. multiformis and N. viennensis, but the effect on N. viennensis was markedly lower. In particular, the effective concentration 50 (EC50) of allylthiourea was 1000 times higher for the AOA culture. Among the tested nitrification inhibitors, DCD was the least potent against N. viennensis. Nitrapyrin had at the maximal soluble concentration only a very weak inhibitory effect on the AOB N. multiformis, but showed a moderate effect on the AOA. The antibiotic sulfathiazole inhibited the bacterium, but barely affected the archaeon. Only the NO-scavenger carboxy-PTIO had a strong inhibitory effect on the archaeon, but had little effect on the bacterium in the concentrations tested. Our results reflect the fundamental metabolic and cellular differences of AOA and AOB and will be useful for future applications of inhibitors aimed at distinguishing activities of AOA and AOB in soil environments.

Topics: Ammonia; Archaea; Benzoates; Fertilizers; Guanidines; Imidazoles; Nitrification; Nitrosomonadaceae; Oxidation-Reduction; Picolines; Sulfathiazole; Sulfathiazoles; Thiourea

Compounds containing cyanoguanidine and 3-amino-1,2,4-benzothiadiazine-1,1-dioxide have been studied as anion receptors and transporters. Significant affinity for oxo-anions was observed in organic solution and the receptors were found to function as transmembrane chloride/nitrate antiporters with transport rates enhanced in the presence of valinomycin-K(+) complex.

Topics: Anion Transport Proteins; Anions; Antiporters; Benzothiadiazines; Cell Membrane Permeability; Cyclic S-Oxides; Guanidines; Models, Molecular; Phosphatidylcholines; Thiourea; Unilamellar Liposomes; Valinomycin

The N,N'-disubstituted cyanoguanidine is an excellent bioisostere of the thiourea and ketene aminal functional groups. We report the design and synthesis of a novel class of cyanoguanidine-based lactam derivatives as potent and orally active FXa inhibitors. The SAR studies led to the discovery of compound 4 (BMS-269223, K(i)=6.5nM, EC(2xPT)=32muM) as a selective, orally bioavailable FXa inhibitor with an excellent in vitro liability profile, favorable pharmacokinetics and pharmacodynamics in animal models. The X-ray crystal structure of 4 bound in FXa is presented and key ligand-protein interactions are discussed.

Topics: Administration, Oral; Animals; Antithrombin III; Benzofurans; Chemistry, Pharmaceutical; Crystallography, X-Ray; Dogs; Guanidines; Haplorhini; Humans; Inhibitory Concentration 50; Kinetics; Lactams; Ligands; Models, Chemical; Rats; Structure-Activity Relationship; Thiourea

A field experiment was conducted on two soil types in the Changsha suburb of Hunan Province to study the effects of hydroquinone (HQ), dicyandiamide (DCD) and thiourea (TU) on the nitrate content in soil and pakchoi and on the yield of pakchoi. The results showed that all the test nitrification inhibitors could significantly decrease the nitrate content in soil and pakchoi during whole growth stage, among which, DCD had the best effect, but the effect was differed on different soil types. Nitrification inhibitors could increase pakchoi yield, DCD was also the best one, and the effect was significantly better on vegetable garden red soil than on vegetable garden alluvial soil. The nitrate content in soil and pakchoi was the highest about 40 days after pakchoi transplanting.

Topics: Guanidines; Hydroquinones; Nitrates; Soil; Thiourea; Vegetables

In an effort to develop new types of antiulcer agents, we synthesized a series of novel 2-[omega-(thioureido)alkyl]- and 2-[omega-(cyanoguanidino)alkyl]-3(2H)-pyridazinone derivatives. All target compounds were evaluated for gastric antisecretory activity in the pylorus-lygated rat by the method of Shay, and selected compounds were evaluated in the stress-induced ulcer test in rats. Structure-activity relationships were established. Two series of the compounds had significant activity in antisecretory and/or antiulcer tests. The molecular features essential for the activities are a thiourea group or a 2-cyanoguanidine group, a phenyl group in the C-6 position of the 3(2H)-pyridazinone ring, a four-carbon chain length between the 3(2H)-pyridazinone ring and the functional group, and a methyl group at the N-3 position of the functional group. Among them, the three thiourea derivatives (24, 26, and 38) and the six 2-cyanoguanidine derivatives (61, 62, 65, 75, 85, and 86) had the most potent antisecretory and/or antiulcer activities. These compounds are not histamine H2-receptor antagonists.

Topics: Acetylcholine; Animals; Gastric Mucosa; Guanidines; Guinea Pigs; Ileum; Male; Pyridazines; Rats; Rats, Inbred Strains; Stomach Ulcer; Stress, Physiological; Structure-Activity Relationship; Thiourea

Topics: Amides; Animals; Guanidines; Guinea Pigs; Histamine H2 Antagonists; In Vitro Techniques; Nitriles; Thioamides; Thiourea