Initial reactions in the biodegradation of 1-chloro-4-nitrobenzene by a newly isolated bacterium, strain LW1

Bacterial strain LW1, which belongs to the family Comamonadaceae, utilizes 1-chloro-4-nitrobenzene (1C4NB) as a sole source of carbon, nitrogen, and energy. Suspensions of 1C4NB-grown cells removed 1C4NB from culture fluids, and there was a concomitant release of ammonia and chloride. Under anaerobic conditions LW1 transformed 1C4NB into a product which was identified as 2-amino-5-chlorophenol by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. This transformation indicated that there was partial reduction of the nitro group to the hydroxylamino substituent, followed by Bamberger rearrangement. In the presence of oxygen but in the absence of NAD, fast transformation of 2-amino-5-chlorophenol into a transiently stable yellow product was observed with resting cells and cell extracts. This compound exhibited an absorption maximum at 395 nm and was further converted to a dead-end product with maxima at 226 and 272 nm. The compound formed was subsequently identified by 1H and 13C NMR spectroscopy and mass spectrometry as 5-chloropicolinic acid. In contrast, when NAD was added in the presence of oxygen, only minor amounts of 5-chloropicolinic acid were formed, and a new product, which exhibited an absorption maximum at 306 nm, accumulated.     

UV absorbent,marmesin, from the bark of Thanakha,<Emphasis Type="Italic">Hesperethusa crenulata</Emphasis> L.

We used solvent extractions, SiO₂ column chromatographies, and HPLC to isolate from the bark of Thanakha (Hesperethusa crenulata L) an active crystalline compound for absorbing UV-A radiation (320 to 380 nm). Analyses of low-and high-resolution FAB-MS revealed a compound, named marmesin, with a formula of C₁₄H₁₄O₄ and a molecular mass of 246. To determine its chemical structure, we conducted 300 MMz NMR analyses using various probes,¹H,¹³C, and DEPT¹³C. Our NMR data showed a structure of 2,3-dihydro-2(1 -hydroxy-1 -methylethyl)-furanocoumarin. This active compound contains UV-absorbing chromophores, an aromatic ring, a double bond at C3-C4, and a carbonyl at C2. Its λ_max is 335 nm, indicating that marmesin could be commercially useful as a natural UV-A-filtering product     

Design,synthesis, and anticancer evaluation of some novel thiourea,carbamimidothioic acid,oxazole, oxazolidine,and 2-amino-1-phenylpropyl-2-chloroacetate derived from L-norephedrine

A novel series of thiourea, carbamimidothioic acid, 4, 5-dihydrooxazole-2-thiol, oxazolidine-2thine, and 2-amino-1-phenylpropyl-2-chloroacetate derivatives was designed and synthesized using 2-amino-1-phenylpropan-1-ol (L-norephedrine) as a strategic starting material. The structures of the newly synthesized compounds were established by elemental analyses, IR, and ¹H NMR and ¹³C NMR spectral data. The compounds were evaluated for their in vitro anticancer activity against various cancer cell lines. The corresponding acetamide, carbamimidothioic acid, and 2-2-amino-1-phenylpropyl-2-chloroacetate derivatives showed almost the same activity as the standard drug doxorubicin against human breast cancer cell line (MCF-7). Also, the acetamide and 2-thioxoimidazolidin-4-one derivatives exhibited higher activity than the reference drug doxorubicin against human colon cancer cell line (HCT 116).     

The importance of Δ1-pyrroline in the aetiology of cerebrocortical necrosis

Bacterial thiaminase I associated with cerebrocortical necrosis of cattle and sheep is shown to utilise Δ¹-pyrroline and related compounds as cosubstrates. The product resulting from the reaction of thiamine and Δ¹-pyrroline is 1-(4-amino-2-methylpyrimidin-5-ylmethyl)-1-pyrrolinium chloride. This compound has been identified in the brains of calves suffering from cerebrocortical necrosis. The implications of these findings in the aetiology of other thiamine-responsive diseases of the central nervous system are briefly discussed.     

Unexpected Shift to a 4-Imino Tautomer Upon N4-Acylation of 5-Methylcytosin-1-yl Nucleoside Analogues

Abstract

In contrast with the behaviour of 5-unsubstituted cytosine nucleoside analogues, 5-methylcytosine derivatives show upon N⁴-benzoylation, commonly used as base protection in oligonucleotide synthesis, a tautomeric change of the base moiety from a 4-amino- into a 4-imino isomer. In the latter form, which is easily diagnosticized by ¹³C NMR and confirmed by X-ray data, the compounds seem to be hydrolytically less stable.     

Synthesis of some new hybride molecules containing several azole moieties and investigation of their biological activities

1,2,4-Triazole-3-one prepared from tryptamine was converted to the corresponding carbothioamides by several steps. Their treatment with ethyl bromoacetate or 4-chlorophenacyl bromide produced the corresponding 5-oxo-1,3-thiazolidine or 3-(4-chlorophenyl)-1,3-thiazole derivatives. Acetohydrazide derivative that was obtained starting from tryptamine, was converted to the corresponding Schiff basis and sulfonamide by the treatment with suitable aldehydes and benzensulphonyl chloride, respectively. 2-[(4-Amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazole-3-yl)methyl]-4-[2-(1H-indole-3-yl)ethyl]-5-methyl-2,4-dihydro-3H-1,2,4-triazole-3-one was synthesized starting from hydrazide via the formation of the corresponding 1,3,4-oxadiazole compound, while the other bitriazole compounds were obtained by intramolecular cyclisation of carbothioamides in basic media. The treatment of 1,2,4-triazole or 1,3,4-oxadiazole compound with several amines generated the corresponding Mannich bases. Ethyl (2-amino-1,3-thiazole-4-yl)acetate was converted to the corresponding 1,3,4-oxadiazole derivative, arylidenehydrazides, 1,2,4-triazole-3-one and 5-oxo-1,3-oxazolidine derivatives by several steps. The structural assignments of new compounds were based on their elemental analysis and spectral (FT IR, ¹H NMR, ¹³C NMR and LC-MS) data. The antimicrobial, antilipase and antiurease activity studies revealed that some of the synthesized compounds showed antimicrobial, antilipase and/or antiurease activity.     

Oxidation of Nitrapyrin to 6-Chloropicolinic Acid by the Ammonia-Oxidizing Bacterium Nitrosomonas europaea

Suspensions of Nitrosomonas europaea catalyzed the oxidation of the commercial nitrification inhibitor nitrapyrin [2-chloro-6-(trichloromethyl)-pyridine]. Rapid oxidation of nitrapyrin (at a concentration of 10 μM) required the concomitant oxidation of ammonia, hydroxylamine, or hydrazine. The turnover rate was highest in the presence of 10 mM ammonia (0.8 nmol of nitrapyrin per min/mg of protein). The product of the reaction was 6-chloropicolinic acid. By the use of ¹⁸O₂, it was shown that one of the oxygens in 6-chloropicolinic acid came from diatomic oxygen and that the other came from water. Approximately 13% of the radioactivity of [2,6-¹⁴C]nitrapyrin was shown to bind to cells. Most (94%) of the latter was bound indiscriminately to membrane proteins. The nitrapyrin bound to membrane proteins may account for the observed inactivation of ammonia oxidation.     

Photoinactivation of the detoxifying enzyme nitrophenol reductase from Rhodobacter capsulatus

The phototrophic bacterium Rhodobacter capsulatus E1F1 detoxifies 2,4-dinitrophenol by inducing an NAD(P)H-dependent iron flavoprotein that reduces this compound to the less toxic end product 2-amino-4-nitrophenol. This nitrophenol reductase was stable in crude extracts containing carotenes, but it became rapidly inactivated when purified protein was exposed to intense white light or moderate blue light intensities, especially in the presence of exogenous flavins. Red light irradiation had no effect on nitrophenol reductase activity. Photoinactivation of the enzyme was irreversible and increased under anoxic conditions. This photoinactivation was prevented by reductants such as NAD(P)H and EDTA and by the excited flavin quencher iodide. Addition of superoxide dismutase, catalase, tryptophan or histidine did not affect photoinactivation of nitrophenol reductase, thus excluding these reactive dioxygen species as the inactivating agent. Substantial protection by 2,4-dinitrophenol also took place when the enzyme was irradiated at a wavelength coinciding with one of the absorption peaks of this compound (365nm). These results suggest that the lability of nitrophenol reductase was due to the absorption of blue light by the flavin prosthetic group, thus producing an excited flavin that might irreversibly oxidize some functional group(s) necessary for enzyme catalysis. Nitrophenol reductase may be preserved in vivo from blue light photoinactivation by the high content of carotenes and excess of reducing equivalents in phototrophic growing cells.Abbreviations 2,4-DNP 2,4-dinitrophenol - ANP 2-amino-4-nitrophenol - EDTA ethylenediamine tetraacetic acid - MES 2-(N-Morpholino) ethanesulfonic acid - NPR nitrophenol reductase     

A cytotoxic deoxocucurbitacin from Desfontainia spinosa

A new cytotoxic triterpene, 11-deoxocucurbitacin I was isolated from Desfontainia spinosa. The structure of this compound was elucidated by extensive analysis of the high field ¹H NMR and ¹³C NMR spectra and field desorption mass spectrometry. This is the first example of a cucurbitacin lacking an 11-keto functionality.     

Synthesis of Glucuronides of Fluoropyrimidine Drugs: N- and O-Glucuronides of 5-Fluorocytosine and 5-Fluorouracil

Abstract

The protected (4a-9a) and deprotected (4b-6b, 8b) glucuronides of 5-fluorocytosine and 5-fluorouracil were synthesized and characterized by mass spectrometry and ¹⁹F, ¹H and ¹³C NMR. The substitution position of the sugar moiety on the pyrimidine ring was determined from the ¹³C NMR chemical shift of the C1′ of the sugar. The α or β configuration of the glucuronide linkage was assigned on the basis of the value of the coupling constant between H1′ and H2′ of the sugar.     

Chemical constituents from Celastrus aculeatus Merr.

Phytochemical investigation of Celastrus aculeatus Merr. led to the isolation of nine compounds. Their structures were identified to be dulcitol (1), β-sitosterol (2), n-tritriacontane (3), nimbidiol (4), pristimerin (5), p-hydroxybenzoic acid (7), vanillic acid (8), 3, 5-dimethoxy-4-hydroxybenzoic acid (9) and a new compound named pristimerol (6) on the basis of mass and NMR spectra. This is the first report of phenolic acids (compounds 7–9) from C. aculeatus Merr. We present the HR-MS, 1D NMR (¹H, ¹³C NMR, DEPT) and 2D NMR (HMBC) data of the new compound (6).     

Synthesis of 1,N6-etheno-2-aza-adenosine (2-aza-epsilon-adenosine): a new cytotoxic fluorescent nucleoside

1,N⁶-Etheno-2-aza-adenosine was synthesized by treating 1,N⁶-etheno-adenosine with alkali, followed by nitrosation. The mechanism of formation of this novel nucleoside was elucidated using adenosine tritiated at C-8 and C-2, and was found to deformylate exclusively at C-2. This new 2-aza nucleoside fluoresces at 494 nm when excited at 358 nm. Toxicity study showed the compound is active in a rat mammary tumor tissue culture line, but inactive in HeLa and Glioma 26 tissue culture lines. It was also found to selectively inhibit the thymidine incorporation into DNA in a rat mammary tumor, but exhibits no ill effect on normal proliferative tissue. The reactive intermediate 3-β-D-ribofuranosyl-4-amino-5-(imidazol-2-yl) imidazole was identified and was found to be an active agent in tissue culture.     

Biosynthesis of a Cyclic Tautomer1of (3-Methylmaleyl)acetone from 4-Hydroxy-3,5-dimethylbenzoate byPseudomonassp. HH35 but Not byRhodococcus rhodochrousN75

Here we report that the bacterial catabolism of 4-hydroxy-3,5-dimethylbenzoic acid 1 takes a different course inRhodococcus rhodochrousN75 andPseudomonassp. strain HH35. The former organism accumulates a degradation metabolite of the acid which we isolated and identified as 2,6-dimethylhydroquinone 2. The latter bacterial strain converts the acid and the hydroquinone into a dead-end metabolite. This novel compound was characterised unequivocally by mass spectrometry and¹H and¹³C NMR and UV spectroscopy as 4-acetonyl-4-hydroxy-2-methylbut-2-en-1,4-olide 4, a cyclic tautomer of (3-methylmaleyl)acetone, which exists as the enol carboxylate form 3 in aqueous solution.     

Solanopubamine,a steroidal alkaloid from Solanum pubescens

Aerial parts of Solanum pubescens yielded a new steroidal alkaloid, solanopubamine, the structure of which was elucidated as 3β-amino-5α,22αH,25βH-solanidan-23β-ol by ¹³C NMR, ¹H NMR, IR, mass spectral analysis and chemical degradation methods.     

Degradation of 4-Chlorophenol at Low Temperature and during Extreme Temperature Fluctuations by Arthrobacter chlorophenolicus A6

Low average temperatures and temperature fluctuations in temperate soils challenge the efficacy of microbial strains used for clean up of pollutants. In this study, we investigated the cold tolerance of Arthrobacter chlorophenolicus A6, a microorganism previously shown to degrade high concentrations of 4-chlorophenol at 28°C. Luciferase activity from a luc-tagged derivative of the strain (A6L) was used to monitor the metabolic status of the population during 4-chlorophenol degradation. The A6L strain could degrade 200–300 g mL^–1 4-chlorophenol in pure cultures incubated at 5°C, although rates of degradation, growth and the metabolic status of the cells were lower at 5°C compared to 28°C. When subjected to temperature fluctuations between 5 and 28°C, A6L continued to degrade 4-chlorophenol and remained active. In soil microcosm experiments, the degradation rates were significantly faster the first week at 28°C, compared to 5°C. However, this difference was no longer seen after 7 days, and equally low 4-chlorophenol concentrations were reached after 17 days at both temperatures. During 4-chlorophenol degradation in soil, CFU and luciferase activity values remained constant at both 5 and 28°C. However, once most of the 4-chlorophenol was degraded, both values decreased by 1–1.5 logarithmic values at 28°C, whereas they remained constant at 5°C, indicating a high survival of the cells at low temperatures. Because of the ability of A. chlorophenolicus A6 to degrade high concentrations of 4-chlorophenol at 5°C, together with its tolerance to temperature fluctuations and stress conditions found in soil, this strain is a promising candidate for bioaugmentation of chlorophenol-contaminated soil in temperate climates.This revised version was published online in November 2004 with corrections to Volume 48.     

Design,synthesis, anti-inflammatory activity and molecular docking of potential novel antipyrine and pyrazolone analogs as cyclooxygenase enzyme (COX) inhibitors

As a part of a directed program for development of new active agents, novel heterocyclic derivatives with antipyrine and pyrazolone moieties -incorporated in- have been designed and synthesized. Starting with 4-arylidene-3-methyl-1-phenyl-5-pyrazolone derivative 2a,b novel Mannich bases derivatives have been synthesized and biologically evaluated for their anti-inflammatory activity. Furthermore, the activity of such compounds has been tested interestingly as COX-1 and COX-2 inhibitors. Structure elucidation of the synthesized compounds was attained by the use of elemental analysis, IR, ¹H NMR, ¹³C NMR, and Mass spectrometry techniques. Compounds 3b, 3d and 4b represent the high % inhibition values for both COX-1 and COX-2. On the other hand, compound 8 showed little selectivity against COX-2 while compound 10 showed good selectivity against COX-1 only. Structure activity relationship has been discussed and the results were confirmed by molecular docking calculations.     

Determination by 1H-NMR of the Stereospecificity of NAD-dependent Plant L-Histidinol Dehydrogenase for Nicotinamide C-4 Hydrogen Transfer

The hydrogen-transfer stereospecificity of cabbage histidinol dehydrogenase at the C-4 position of NAD ⁺ was determined by means of ¹H-NMR. A dehydrogenase reaction with enzymatically prepared [4-²H]NAD ⁺ was performed. The NMR spectrum of the reaction mixture showed a peak at about 2.8 ppm, indicating the production of [(4S)-²H]NADH, indicating that the stereospecificity of the enzyme was pro-R-specific.     

Microginin FR1, a linear peptide from a water bloom of Microcystis species

A so far unknown structural variant, called microginin FR1, of cyanobacterial peptides of the microginin type was isolated from a water bloom of a German lake. The bloom consisted almost exclusively of Microcystis sp. cells. The structure of microginin FR1 was identified by amino acid analysis, determination of the relative molecular mass by electrospray mass spectrometry, and by NMR to be a linear pentapeptide with a relative molecular mass of 727 which contains a β-amino-α-hydroxy-decanoic acid (Ahda), alanine, N-methyl-leucine, and two tyrosine units (Ahda-Ala-N-Me-Leu-Tyr-Tyr). Microginin FR1 had angiotensin-converting enzyme inhibitory activity with half-maximal inhibition at 6×10⁻⁵ M microginin FR1.     

Comparison and optimization of transient transfection methods at human astrocytoma cell line 1321N1

A simple, ultrasensitive, nonextractive spectrophotometric method has been developed for the assay of Mo(VI), which involves Mo-catalyzed oxidation of 4-amino-5-hydroxynaphthalene-2,7-disulfonic acid monosodium salt (AHNDSA) by H₂O₂ in acetic acid/sodium acetate buffer yielding an intense pink colored product with λ_max of 540 nm. Beer’s law is obeyed in the range of 10–240 ng/ml with molar absorptivity of 3.0137 × 10⁵ L mol⁻¹ cm⁻¹. The LOD and LOQ were found to be 0.7696 and 2.565 ng/ml, respectively. The applicability of the method toward water and biological samples was tested and statistically compared with a reference method.     

AMPK and SIRT1 activation contribute to inhibition of neuroinflammation by thymoquinone in BV2 microglia

Pyrazole moiety represents an important category of heterocyclic compound in pharmaceutical and medicinal chemistry. The novel 1-aryl-3, 5-bis (het) aryl pyrazole derivatives were synthesized with complementary regioselectivity. The chemical structures were confirmed by IR, ¹H NMR, ¹³C NMR, and mass spectral analysis. The chemical entities were screened in various cancer cell lines to assess their cell viability activity. Results showed that the compound 3-(1-(4-bromophenyl)-5-phenyl-1H-pyrazol-3-yl) pyridine (5d) possessed maximum cytotoxic effect against breast cancer and leukemic cells. The cytotoxicity was confirmed by live–dead cell assay and cell cycle analysis. Mitochondrial membrane potential, Annexin V-FITC staining, DNA fragmentation, Hoechst staining, and western blot assays revealed the ability of compound 5d to induce cell death by activating apoptosis in cancer cells. Thus, the present study demonstrates that compound 5d could be an attractive chemical entity for the development of small molecule inhibitors for treatment of leukemia and breast cancer.