鲁氏接合酵母对酱油中氨基甲酸乙酯前体物的代谢

【目的】研究鲁氏接合酵母氮源代谢特性,确定鲁氏接合酵母氮源代谢与酱油中氨基甲酸乙酯前体物瓜氨酸和尿素积累的关系。【方法】通过单一氮源培养、偏好型氮源培养和盐胁迫培养,检测不同条件下鲁氏接合酵母对精氨酸、瓜氨酸和尿素的代谢能力。【结果】通过对鲁氏接合酵母氨基酸利用能力的分析,确定了甘氨酸、丙氨酸和天冬酰胺3种氨基酸为鲁氏接合酵母的偏好型氮源。在偏好型氮源存在时,鲁氏接合酵母对尿素和瓜氨酸的利用并不受到抑制,丙氨酸和甘氨酸还能够促进对二者的利用。鲁氏接合酵母在单一氮源培养条件下不会降解精氨酸而积累尿素和瓜氨酸,反而可以大量利用氨基甲酸乙酯的前体物尿素和瓜氨酸。但在盐胁迫下,鲁氏接合酵母利用尿素和瓜氨酸受到阻遏,从而造成酱油中氨基甲酸乙酯前体物不能被充分利用而积累。【结论】盐胁迫阻遏了鲁氏接合酵母对瓜氨酸和尿素的利用,从而造成酱油发酵过程中耐盐细菌所产生的氨基甲酸乙酯前体物的积累。     

高通量筛选诱变菌株降低黄酒发酵氨基甲酸乙酯前体积累

【目的】氨基甲酸乙酯是发酵食品中普遍存在的一种潜在危害物。黄酒中氨基甲酸乙酯的前体主要是尿素和乙醇。本研究通过高通量筛选策略降低黄酒发酵过程中尿素的积累,从而降低氨基甲酸乙酯积累。【方法】以一株黄酒生产工业菌株酿酒酵母XZ-11为研究对象,采用ARTP诱变和高通量筛选策略,获得尿素积累量较低菌株。使用实时定量PCR技术检测氮代谢中尿素代谢和转运相关基因(DUR1,2和DUR3)的变化。【结果】筛选得到一株尿素高效稳定性利用菌株5-11C。其尿素积累量比酿酒酵母XZ-11降低了50.6%。实时定量荧光PCR结果表明,与尿素代谢和转运相关的基因(DUR1,2和DUR3)表达量分别提高了3.3和2.2倍。【结论】高通量筛选策略可以用于降低黄酒生产过程中氨基甲酸乙酯前体尿素的含量。由于未采用基因工程手段,避免了可能的法规问题,消费者易于接受,在发酵食品行业具有较好的应用前景。     

Development of a biosensor for urea assay based on amidase inhibition,using an ion-selective electrode

Abstract

A biosensor for urea has been developed based on the observation that urea is a powerful active-site inhibitor of amidase, which catalyzes the hydrolysis of amides such as acetamide to produce ammonia and the corresponding organic acid. Cell-free extract from Pseudomonas aeruginosa was the source of amidase (acylamide hydrolase, EC 3.5.1.4) which was immobilized on a polyethersulfone membrane in the presence of glutaraldehyde; an ion-selective electrode for ammonium ions was used for biosensor development. Analysis of variance was used for optimization of the biosensor response and showed that 30 μL of cell-free extract containing 7.47 mg protein mL^?1, 2 μL of glutaraldehyde (5%, v/v) and 10 μL of gelatin (15%, w/v) exhibited the highest response. Optimization of other parameters showed that pH 7.2 and 30 min incubation time were optimum for incubation of membranes in urea. The biosensor exhibited a linear response in the range of 4.0–10.0 μM urea, a detection limit of 2.0 μM for urea, a response time of 20 s, a sensitivity of 58.245 % per μM urea and a storage stability of over 4 months. It was successfully used for quantification of urea in samples such as wine and milk; recovery experiments were carried out which revealed an average substrate recovery of 94.9%. The urea analogs hydroxyurea, methylurea and thiourea inhibited amidase activity by about 90%, 10% and 0%, respectively, compared with urea inhibition.     

Diheteroarylurea derivatives as adventitious rooting adjuvants in mung bean shoots and M26 apple rootstock

The present research investigates the biological profile of eight symmetrical diheteroarylureas and phenylheteroarylureas, testing their hypothetical cytokinin-like activity and rooting activity. Cytokinin-like activity was assayed by the betacyanin (so-called amaranthin) accumulation test and by the tomato regeneration test. The rooting activity was assessed using the mung bean rooting test, the apple stem slice test and the rooting of apple microcuttings. Three compounds, 1,3-di(pyrazin-2-yl)urea (3a), 1,3-di(benzo[d]oxazol-5-yl)urea (3b) and 1,3-di(benzo[d]oxazol-6-yl)urea (3c), enhanced adventitious root formation in apple stem slice test, but only 3b and 3c were active in the mung bean rooting test. Compound 3b, that showed the best rooting activity, was also able to enhance the adventitious root formation in apple microcuttings. None of the compounds showed cytokinin-like activity.     

Excretion of ammonia and urea during development in the oyster toadfish,Opsanus tau

The oyster toadfish is one of several teleosts that has been found to produce and excrete large amounts of nitrogenous waste as urea. To clarify the role of urea in the oyster toadfish, urea and ammonia excretion rates were examined in developing fish. Ammonia and urea excretion rates were measured for groups of developing toadfish for three days a week over eight weeks of development. A distinct and significant increase in the excretion rate of urea occurred between the first three weeks (mean = 0.38 mg N/kg‐h) and the fourth through sixth and eighth week of development (mean = 4.68 mg N/kg‐h). This increase of urea excretion occurs at the time of hatching and may be important during development. Preliminary analysis (temperature, pH and salinity) was conducted on water at one toadfish nesting site to provide insight into conditions to which toadfish are exposed.     

Alteration of the groove width of DNA induced by the multimodal hydrogen bonding of denaturants with DNA bases in its grooves affects their stability

BackgroundDenaturants, namely, urea and guanidinium chloride (GdmCl) affect the stability as well as structure of DNA. Critical assessment of the role of hydrogen bonding of these denaturants with the different regions of DNA is essential in terms of its stability and structural aspect. However, the understanding of the mechanistic aspects of structural change of DNA induced by the denaturants is not yet well understood.MethodsIn this study, various spectroscopic along with molecular dynamics (MD) simulation techniques were employed to understand the role of hydrogen bonding of these denaturants with DNA bases in their stability and structural change.Results and conclusionIt has been found that both, GdmCl and urea intrude into groove region of DNA by striping surrounding water. The hydrogen bonding pattern of Gdm⁺ and urea with DNA bases in its groove region is multimodal and distinctly different from each other. The interaction of GdmCl with DNA is stabilized by electrostatic interaction whereas electrostatic and Lennard-Jones interactions both contribute for urea. Gdm⁺ forms direct hydrogen bond with the bases in the minor groove of DNA whereas direct and water assisted hydrogen bond takes place with urea. The hydrogen bond formed between Gdm⁺ with bases in the groove region of DNA is stronger than urea due to strong electrostatic interaction along with less self-aggregation of Gdm⁺ than urea. The distinct hydrogen bonding capability of Gdm⁺ and urea with DNA bases in its groove region affects its width differently. The interaction of Gdm⁺ decreases the width of the minor and major groove which probably increases the strength of hydrogen bond between the Watson-Crick base pairs of DNA leading to its stability. In contrast, the interaction of urea does not affect much to the width of the grooves except the marginal increase in the minor groove width which probably decreases the strength of hydrogen bond between Watson Crick base pairs leading to the destabilization of DNA.General significanceOur study clearly depicts the role of hydrogen bonding between DNA bases and denaturants in their stability and structural change which can be used further for designing of the guanidinium based drug molecules.     

Relationship Between IL-2, IL-17 Concentrations,and Serum Creatinine Levels in Men with Chronic Kidney Diseases

Background:Chronic kidney disease (CKD), is a major public health challenge worldwide. It is more prevalent in developed countries compared with the rest of the world, due to the higher rates of life expectancy and unhealthy lifestyle related factors. This aim of the current study is to evaluate the relationship between interleukins IL-2 and IL-17 concentrations and kidney function markers in men with CKD.Methods:Forty-five men with CKD and seventy controls were enrolled in the current study to assess the relationship between interleukin-2 (IL-2), interleukin-17 (IL-17), and CKD parameters. Fasting blood samples were collected from patients with CKD and their controls at same time. Serum IL-2, and IL-17 were measured in patients with CKD and their controls, and then the relationship between these interleukins and serum creatinine, serum urea, serum uric acid and urine albumin were evaluated.Results:A significant relationship was detected between IL-2 (p< 0.001), IL-17 (p< 0.001) levels and serum creatinine concentrations. The significant increase of IL-2 and IL-17 levels were also paralleled with a significant increase in serum urea (p< 0.001), and urine albumin (p< 0.001) concentrations respectively.Conclusion:IL-2 and IL-17 may play a critical role in the pathophysiology of CKD. The significant increase of IL-2 and IL-17 is associated with significantly high concentrations of creatinine, serum urea and urine albumin suggesting that these interleukins may be used as targets for future biomarkers and molecular therapy. However, due to limited sample size of the current study, larger prospective cohorts are needed to confirm these observations.Key Words: Chronic kidney disease, Interleukins, Serum creatinine, Serum urea, Urine albumin     

Synthesis,characterization, antiamoebic activity and cytotoxicity of new pyrazolo[3, 4-d]pyrimidine-6-one derivatives

A new series of pyrazolo[3,4-d]pyrimidine-6-one derivatives (2a–2j) were prepared by using the Biginelli multicomponent cyclocondensation of 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one (1a), different aromatic aldehydes, and urea with a catalytic amount of HCl at reflux temperature. These compounds were characterized by IR, ¹H NMR, ¹³C NMR, and Mass spectral data. In vitro antiamoebic activity was performed against HM1:IMSS strain of Entamoeba histolytica. The results showed that the compounds 2b, 2i, and 2j with IC₅₀ values of 0.37 µM, 0.04 µM, and 0.06 µM, respectively, exhibited better antiamoebic activity than the standard drug metronidazole (IC₅₀?=?1.33 µM). The toxicological studies of these compounds on human breast cancer MCF-7 cell line showed that the compounds 2b, 2i, and 2j exhibited >80% viability at the concentration range of 1.56–50 µM.     

Sequence specific hydrogen bond of DNA with denaturants affects its stability: Spectroscopic and simulation studies

BackgroundSeveral different small molecules have been used to target the DNA helix in order to treat the diseases caused by its mutation. Guanidinium(Gdm⁺) and urea based drugs have been used for the diseases related to central nervous system, also as the anti-inflammatory and chemotherapeutic agent. However, the role of Gdm⁺ and urea in the stabilization/destabilization of DNA is not well understood.MethodsSpectroscopic techniques along with molecular dynamics (MD) simulation have been performed on different sequences of DNA in the presence of guanidinium chloride (GdmCl) and urea to decode the binding of denaturants with DNA and the role of hydrogen bond with the different regions of DNA in its stability/destability.Results and conclusionOur study reveals that, Gdm⁺ of GdmCl and urea both intrudes into the groove region of DNA along with the interaction with its phosphate backbone. However, interaction of Gdm⁺ and urea with the nucleobases in the groove region is different. Gdm⁺ forms the intra-strand hydrogen bond with the central region of the both sequences of DNA whereas inter-strand hydrogen bond along with water assisted hydrogen bond takes place in the case of urea. The intra-strand hydrogen bond formation capability of Gdm⁺ with the nucleobases in the minor groove of DNA decreases its groove width which probably causes the stabilization of B-DNA in GdmCl. In contrast, the propensity of the formation of inter-strand hydrogen bond of urea with the nucleobases in the groove region of DNA without affecting the groove width destabilizes B-DNA as compared to GdmCl. This study depicts that the opposite effect of GdmCl and urea on the stability is a general property of B-DNA. However, the extent of stabilization/destabilization of DNA in Gdm⁺ and urea depend on its sequence probably due to the difference in the intra/inter-strand hydrogen bonding with different bases present in both the sequences of DNA.General significanceThe information obtained from this study will be useful for the designing of Gdm⁺ based drug molecule which can target the DNA more specifically and selectively.     

玉肤解毒膏治疗结直肠癌患者卡培他滨化疗所致手足综合征的疗效观察

摘要 目的：观察玉肤解毒膏治疗结直肠癌患者卡培他滨化疗所致手足综合征的临床疗效,为临床提供合理治疗方案。方法：选择2021年月-2022年5月湖南省肿瘤医院门诊或住院部确诊为结直肠癌行含卡培他滨方案化疗所致手足综合征患者60例。所有患者采用抛掷硬币法分为玉肤解毒膏组和尿素软膏组,各30例。玉肤解毒膏组采用玉肤解毒膏治疗;尿素软膏组采用尿素软膏治疗,2组均连续治疗21 d。观察2组手足综合征分级改善情况、临床疗效、中医证候积分、疼痛视觉模拟评分（VAS）、手足皮肤反应生活质量量（HF-QoL）评分及焦虑自评量表（SAS）评分。结果：玉肤解毒膏组在降低手足综合征分级及提高治疗总有效率上均优于尿素软膏组（P＜0.05）;治疗后2组中医证候积分、VAS评分、HF-QoL评分及SAS评分较治疗前降低（P＜0.05）,且玉肤解毒膏组均低于尿素软膏组（P＜0.05）。结论：玉肤解毒膏治疗结直肠癌患者卡培他滨化疗所致手足综合征的临床疗效确切,可有效降低患者临床分级,降低中医证候积分、缓解疼痛症状,改善患者生活质量及焦虑状况,具有一定的临床应用价值。     

Synthesis,Antitumor, and DNA Binding Behavior of Novel 4-(2-Hydroxyquinolin-3-yl)-6-Phenyl-5, 6 Dihydropyrimidin Derivatives in Aqueous Medium

This article deals with the synthesis of 4-(2-hydroxyquinolin-3-yl)-6-phenyl-5,6-dihydropyrimidin derivatives (2a–f), on condensation with various aromatic aldehydes and ketones in aqueous ethanolic NaOH solution yielding the corresponding chalcones (3). These chalcones were further reacted with thiourea/urea in the presence of a base, which led to the formation of the titled derivatives (2a–f). The newly synthesized heterocyles were characterized by elemental analysis, FTIR, ¹HNMR, and electronic and mass spectral data. The compounds (2a and 2b) were evulated for in vitro cyctotoxicity against human breast adenocarcinoma cell (MCF-7). In MTT cytotoxicity studies, both quinolinde derivatives were found most effective. The binding interaction behavior of the compound (2a) and (2d) with calf thymus-DNA (CT-DNA) was studied by electronic spectra, viscosity measurements, and thermal denaturation studies. On binding to CT-DNA, the absorption spectrum underwent bathochromic and hypochromic shifts. The binding constant (K_b) observed 4.3 × 10⁵ M^?1 for (2a), and 3.8 × 10⁵ M^?1 for (2d) suggested that compound (2a) binds more strongly with base pairs than (2d).     

N-monoarylacetothioureas as potent urease inhibitors: synthesis,SAR, and biological evaluation

Abstract

A urease inhibitor with good in vivo profile is considered as an alternative agent for treating infections caused by urease-producing bacteria such as Helicobacter pylori. Here, we report a series of N-monosubstituted thioureas, which act as effective urease inhibitors with very low cytotoxicity. One compound (b19) was evaluated in detail and shows promising features for further development as an agent to treat H. pylori caused diseases. Excellent values for the inhibition of b19 against both extracted urease and urease in intact cell were observed, which shows IC₅₀ values of 0.16?±?0.05 and 3.86?±?0.10?µM, being 170- and 44-fold more potent than the clinically used drug AHA, respectively. Docking simulations suggested that the monosubstituted thiourea moiety penetrates urea binding site. In addition, b19 is a rapid and reversible urease inhibitor, and displays nM affinity to urease with very slow dissociation (k _off=1.60?×?10^?3 s^?1) from the catalytic domain.     

Within- and among-population variation in oviposition preference for urea-supplemented food inDrosophila melanogaster

Oviposition preference for ureasupplemented food was assayed by simultaneous choice trials on five pairs of closely related laboratory populations of Drosophila melanogaster.Each pair of populations had been derived from a separate ancestral population about 85 generations prior to this study. One population in each pair had been subjected to selection for larval tolerance to the toxic effects of urea; the other population served as a control. Considerable variation in oviposition preference was seen both within and among populations, with four of the ten populations showing a significant mean preference for ureasupplemented food. The degree of specificity shown by individual females was surprisingly high, leading to a bimodal distribution of oviposition preference in some populations. Overall, selection for larval tolerance to urea did not significantly affect oviposition preference. However, the data indicated that pairwise comparisons between randomly selected populations from the two larval selection regimes would lead to a range of possible outcomes, suggesting, in several cases, that selection for larval urea tolerance had led to significant differentiation of adult oviposition preference for urea in one or the other direction. The results, therefore, highlight the importance of population level replication and caution against the practice, common in ecological studies, of assaying oviposition preference in two populations that utilize different hosts in nature, and then drawing broad evolutionary inferences from the results.     

Molecular Mechanics Evaluation of the Proposed Mechanisms for the Degradation of Urea by Urease

Abstract

A thorough conformational search of all the conformations available to oxygen-bound urea within wild-type urease was carried out. Identical low energy urea conformations were obtained by a Ramachandran type plot for the N_His272-Ni1-O-C_urea and Ni1-O-Curea-N_urea dihedral angles. Ramachandran plots, with active sites and protonation states modified to model the different urease mechanisms, were used to evaluate the different mechanisms. Based upon the low energy conformations available to urea in the active site of wild-type urease one can conclude that the traditional “His320 acts as a base” mechanism is unlikely, while the N,O urea bridged and the reverse protonation mechanisms cannot be ruled out. A consensus hydrogen-bonding network that does not favor any of the mechanisms has been reconfirmed by the extensive conformational search.     

Condition of large brood in Bonelli's Eagle Hieraaetus fasciatus

Capsule Young body condition is affected by the interaction of environment (rainfall) and brood size.

Aims To investigate factors affecting offspring condition using levels of urea in plasma.

Methods We used generalized linear mixed models (GLMMs) with the levels of urea in plasma as the dependent variable and laying date, brood size, sex and year as the explanatory ones.

Results Brood size had a significant effect on offspring condition only during a year of adverse weather (heavy rainfall). During this period, young from broods of two were in poor condition compared with single broods. Conversely, brood size had no effect in the other two years analysed. Neither sex nor laying date had a significant effect on young condition. Offspring condition was not related to first-year survival.

Conclusion There is a trade-off between reproduction (brood size) and offspring condition only in years of adverse environmental conditions.     

Metal-directed and ligand-distorted assembly of chiral/achiral one-dimensional coordination polymers: Syntheses, structures and physical properties

The hydrothermal reactions of 5-bromoisophthalic acid (H₂BIPA) and metal salts in the presence of pyridine (py) result in three new coordination polymers, namely, M(BIPA)(py)₃ [M = Co(II) (1), Ni(II) (2)] and Zn(BIPA)(py)₂·H₂O (3), all of which have been characterized by single-crystal X-ray, elemental analysis, infrared spectroscopy, and thermogravimetric analysis. Compounds 1 and 2 are isostructural and contain 2₁ helical chains made up of metal ions and BIPA²⁻ ligand, the chains are further formed to the supramolecular structures by the π?π interactions between the adjacent parallel py rings. Compound 3 has a 1D chiral left-handed helical chain structure. It is notable that 3 is obtained by second order spontaneous resolution using achiral starting materials. Moreover, the solid-state CD spectrum of single crystals and powder samples of 3 is investigated. The nonlinear optical measurement shows that 3 displayed a second-harmonic-generation (SHG) response of 0.7 times that for urea.     

精氨酸代谢调控蛋白ArgR调控嗜热链球菌胞外多糖合成

[目的] 研究精氨酸代谢调控蛋白ArgR对嗜热链球菌胞外多糖（EPS）合成的调控作用。[方法] 利用大肠杆菌异源表达嗜热链球菌ArgR蛋白,通过尿素变性-复性和Ni²⁺亲和层析纯化。采用凝胶电泳迁移（EMSA）和生物膜层干涉（BLI）分析ArgR和eps基因簇中P_epsA启动子的相互作用和动力学信息。构建过表达和弱化argR基因菌株,利用苯酚-硫酸法测定其合成EPS差异。[结果] 大肠杆菌异源表达的ArgR为包涵体,使用尿素变性-复性纯化可获得2.95 mg/mL可溶性蛋白;EMSA和BLI结果显示ArgR和启动子P_epsA有特异性结合,且结合因解离水平低而稳定;过表达argR基因可显著降低嗜热链球菌EPS合成,而弱化argR基因则提高EPS合成。[结论] 本研究表明ArgR能特异性结合嗜热链球菌eps基因簇启动子,并负调控EPS生物合成。     

Expression, Purification, Characterization, and X-Ray Analysis of Selenomethionine 215 Variant of Leukocyte Collagenase

Matrix metalloproteinases belong to the superfamily of metzincins containing, besides a similar topology and a strictly conserved zinc environment, a 1,4-tight turn with a strictly conserved methionine residue at position three (the so called Met-turn [Bode et al. (1993) FEBS 331, 134–140; Stöcker et al. (1995) Protein Sci. 4, 823–840]. The distal S–CH₃ moiety of this methionine residue forms the hydrophobic basement of the three His residues liganding the catalytic zinc ion. To assess the importance of this methionine, we have expressed the catalytic domain of neutrophil collagenase (rHNC, residues Met80–Gly242) in the methionine auxotrophic Escherichia coli strain B834[DE3](hsd metB), with the two methionine residues replaced by Selenomethionine. Complete replacement was confirmed by amino acid analysis and electrospray mass spectrometry. The folded and purified enzyme retained its catalytic activity, but showed modifications which are reflected in changed kinetic parameters. The Met215SeMet substitution caused a decrease in conformational stability upon urea denaturation. The X-ray crystal structure of this Selenomethionine rHNC was virtually identical to that of the wild-type catalytic domain except for a very faint local disturbance around the sulfur-seleno substitution site.     

Effect of Zinc Ions on Conformational Stability of Yeast Alcohol Dehydrogenase

Yeast alcohol dehydrogenase preparations were prepared with the conformational zinc ion removed (Apo-I YADH) and with both the conformational and catalytic zinc ions removed (Apo-II YADH). The unfolding of Apo-I YADH and Apo-II YADH during denaturation in urea solutions was then followed by fluorescence emission, circular dichroism, and second-derivative optical spectroscopies. Compared with the native enzyme, Apo-I YADH incurred some slight unfolding, and its stability against urea was markedly decreased, while Apo-II YADH incurred marked unfolding but contained residual ordered structure even at high urea concentrations. The results show that native YADH is more conformationally stable against urea denaturation than Apo-I YADH, indicating that the conformational Zn²⁺ plays an important role in stabilizing the conformation of the YADH molecule. However, unfolding of the region around the conformational zinc ion is shown not to be the rate limited step in the unfolding of the molecule by the fact that the unfolding and inactivation rate constants of native and Apo-I YADH are the same. It is suggested that the catalytic zinc ion is more important in maintaining the structure of YADH. YADH lost its cooperative unfolding ability after the zinc ions were removed. The shape of the transition curves of Apo-I YADH suggests the existence of an unfolding intermediate. For both native and Apo-I YADH, inactivation occurs at much lower urea concentrations than that needed to produce significant conformational changes of the enzyme molecule. At urea concentration above 4 M, the inactivation rate constants are much higher than those of the fast phase of the reaction of unfolding. These results support the suggestion of flexibility at the active site of the enzyme (C. L. Tsou (1986) Trends Biochem. Sci., 11, 427-429; (1993) Science, 262, 308-381).     

Synthesis and Biological Activity of Urea and Thiourea Derivatives from 2-Aminoheterocyclic Compounds

Thirty-eight N-substituted-N′-(2-thiozolyl and furfuryl)ureas and thioureas were prepared by reaction of 2-aminothiazole and 2-furfurylamine with the appropriate iso(thio)cyanate. All compounds were tested for herbicidal activity and selectivity on seedlings of wheat (a monocotyledonous plant) and cucumber (a dicotyledonous plant). Only one compound (1) out of 14 ureas was characterized by considerable herbicidal activity against the wheat seedlings and two compounds (1 and2)-towards the cucumber seedlings. The phenylurea derivative of 2-aminothiazole (1) was 1.7-fold more and the 3-chlorophenylurea derivative of 2-furfurylamine (23) was equally as active as the standard diuron with respect to selective herbicidal activity. Among 24 thioureas, four compounds (15, 16, 17, and18) to displayed the highest selective herbicidal activity and two other compounds (19 and33) were almost equal to diuron activity. Selective herbicidal ratio (SHR) represents the degree of herbicidal effect of the investigated compounds compared to diuron at both test objects. Four compounds (16,17,18, and23) possessed SHR ≪100 in the wheat seedlings while in the cucumber seedlings they had SHR ≫ 100. Therefore these compounds were substantially more active herbicides to the wheat seedlings as compared to diuron. The cytokinin-like activity of the synthesized compounds was also investigated in terms of betacyanin synthesis and radish cotyledon enlargement. The urea derivatives exhibited mostly high cytokinin-like activity but their activity remained lower than those of kinetin and N-phenyl-N′-(4-pyridyl)urea. The N-(3-fluorophenyl)-N′-(2-thiazolyl)urea (2) possessed the greatest activity at 10 μM while the corresponding compound with 3-chlorophenyl (4) was the most active cytokinin-like substance in the whole concentration range tested. Attention was also given to structure-activity relationships for the screened compounds. In general, the ureas and thioureas containing a 2-thiazole ring were more active than those containing a 2-furfuryl residue. Online publication: 7 April 2005