Pyrimidine nucleoside, pseudouridine, and modified nucleoside excretion by growing and resting fibroblasts.

We are examining the relationship of RNA metabolism and de novo pyrimidine synthesis as parameters of malignant transformation. These initial experiments on normal hamster embryo fibroblasts have shown that excreted nucleosides are markers for intracellular RNA metabolism. We employed affinity chromatography to concentrate the nucleosides in the medium and sensitive column chromatographic procedures to quantitatively measure them. The excretion of pyrimidine nucleoside from hamster embryo fibroblasts in sulture was found to be dependent on the growth state of the cells, with the greatest accumulation occurring cell quiescence. The major nucleoside excretion products, uridine and cytidine, were both normal end products of RNA metabolism and the major nucleoside excretion products from cultured cells. The modified nucleosides N-1-methylguanosine, N-2-methylguanosine, N-2-dimethylguanosine, N-4-acetylcytidine, N-1-methylinosine, pseudouridine, N-1-methyladenosine, N-3-methylcytidine, and 5-methyleycytidine were found, as were several unidentified nucleosides.     

Fates of N′-Methylnicotinamide and Nicotinamide N-Oxide in Mice

This experiment was performed to investigate the possibility that N′ -methylnicotinamide (N′-methyl-3-pyridinecarboxamide) and nicotinamide N-oxide have niacin activity or not in animals. When 20 mg N′-methylnicotinamide per mouse was administered, urinary excretion of nicotinamide, N¹-methylnicotinamide (MNA), N¹-methyl-2-pyridone-5-carboxamide (2-Py), and N¹-methyl-4-pyridone-3-carboxamide (4-Py) increased 24-, 3-, 3-, and 3-fold, respectively, compared with the control values. The increased ratios of MNA, 2-Py, and 4-Py were almost the same as those when 20 mg nicotinamide was administered. Therefore, the relative activity of N′-methylnicotinamide to nicotinamide as niacin was considered to be about 1. When 20 mg nicotinamide N-oxide per mouse was administered, urinary excretion of nicotinamide, MNA, 2-Py, and 4-Py increased 6.4-, 1.8-, 1.6-, and 1.7-fold, respectively, compared with the control values. The increased ratios of MNA, 2-Py, and 4-Py were about 1/2 of those when 20 mg nicotinamide was administered, so the relative activity of nicotinamide N-oxide to nicotinamide as niacin is considered to be about 1/2. In conclusion, it was found the possibility that the reactions N′-methylnicotinamide → nicotinamide and nicotinamide N-oxide → nicotinamide occur, at least in mice, and that therefore N′-methylnicotinamide and nicotinamide N-oxide have niacin activity.     

99mTc-tricarbonyl labeled agents for cell labeling: Development,biodistribution in normal mice and preliminary in vitro evaluation

We have developed four ^99mTc(CO)₃-labeled lipophilic tracers as potential radiolabeling agents for cells based on a hexadecyl tail. ^99mTc(CO)₃-hexadecylamino-N,N′-diacetic acid (negatively charged), ^99mTc(CO)₃-hexadecylamino-N-α-picolyl-N′-acetic acid (uncharged), ^99mTc(CO)₃-N,N′-dipicolylhexadecylamine (positively charged), ^99mTc(CO)₃-N-hexadecylaminoethyl-N′-aminoethylamine (positively charged) were prepared in a radiolabeling yield: >90%. Preliminary cell uptake studies were performed in mixed blood cells with or without plasma and were compared with ^99mTc-d,l-HMPAO and [¹⁸F]FDG. In plasma-free blood cells, maximum uptake (78%) was obtained for ^99mTc(CO)₃-N-hexadecylaminoethyl-N′-aminoethylamine after 60 min incubation (compared to 55% and 23% for ^99mTc-d,l-HMPAO and [¹⁸F]FDG, respectively) while in plasma-rich medium, ^99mTc(CO)₃-N,N′-dipicolylhexadecylamine was best bound (54%, similar to the binding of ^99mTc-d,l-HMPAO). Biodistribution in normal mice showed mainly hepatobiliary clearance of the agents and initial high lung uptake. The radiolabeled compounds showed good blood clearance with maximally 7.9% injected dose per gram at 60 min post injection. While the least lipophilic agent (^99mTc(CO)₃-N,N′-dipicolylhexadecylamine, log P = 1.3) showed the best cell uptake, there appears to be no direct correlation between lipophilicity and tracer uptake in mixed blood cells. In view of its comparable cell uptake to well known cell labeling agent ^99mTc-d,l-HMPAO, ^99mTc(CO)₃-N,N′-dipicolylhexadecylamine merits further evaluation as a potential cell labeling agent.     

TRANSFER OF N2 AND CO2 FIXATION PRODUCTS FROM ANABAENA OSCILLARIOIDES TO ASSOCIATED BACTERIA DURING INORGANIC CARBON SUFFICIENCY AND DEFICIENCY1

Transfer of N₂ and CO₂ fixation products from the bloom forming blue-green alga, Anabaena oscillarioides Bory, to attached and free swimming bacteria is common during active growth of the former. Incubation with ¹⁵N₂ and ¹⁴CO₂ followed by size fractionation filtration reveals that: i) magnitudes of fixed N and C excretion, relative to N₂ and CO₂ fixation, are dictated by dissolved inorganic carbon (DIC) availability for A. oscillarioides photosynthetic production, ii) associated bacteria exhibit preferences for recently fixed excreted N compounds, iii) bacterial utilization of excreted N is independent of ambient light conditions, and iv) lag times between N₂ fixation and detectable bacterial assimilation of excreted fixed N compounds are ca. 1–2 h. Both ¹⁴NH₄Cl dilution and Hg(NH₃)₂ Cl₂ precipitation techniques indicate that NH₃ is a major excretion product from A. oscillarioides, particularly during DIC limited growth. Active N and C excretion and transfer to associated bacteria are features of viable A. oscillarioides filaments. Hence, transfer of these metabolites reflects complex mutualistic, and possibly symbiotic associations rather than solely signaling senescence.     

An investigation of glycolate excretion in two species of blue-green algae

Summary The amount of ¹⁴C-glycolate excreted by Oscillatoria sp. and Anabaena flos-aquae is less than 1% of the ¹⁴C fixed by the algae during photosynthesis. Transfer of cells grown on 5% CO₂ in air to a medium of low bicarbonate concentration or treatment of the cells with isonicotinyl hydrazide (INH) during photosynthesis, caused little increase in glycolate excretion. -Hydroxysulfonates failed to stimulate massive excretion of glycolate. Although these blue-green algae excreted little glycolate, a significant proportion of the photosynthetically fixed carbon was excreted in the form of basic, neutral and acidic compounds, and such excretion was greater in 5% CO₂-grown cells than in air-grown cells.     

Denitrification in Rhodopseudomonas sphaeroides f. denitrificans

Rhodopseudomonas sphaeroides f. denitrificans grown photosynthetically with NO ₃ ^- under anaerobic conditions accumulated NO ₂ ^- in the culture medium. In washed cells succinate, lactate, fumarate, citrate and malate, were effective electron donors for the reduction of NO ₃ ^- , NO ₂ ^- and N₂O to N₂ gas. Nitrate reductase was inhibited by amytal and potassium thocyanate. Nitrite reductase activity was severely restricted by potassium cyanide, sodium diethyldithiocarbamate, Amytal and 2-n-heptyl-4-hydroxyquinoline-N-oxide whereas N₂O reductase was inhibited by NaN₃, C₂H₂ and KCNS. Cells incubated with either K¹⁵NO₃ or K¹⁵NO₂ produced ¹⁵N₂O and ¹⁵N₂. A stoichiometry of 2:1 was recorded for the reduction of either NO ₃ ^- or NO ₂ ^- to N₂O and N₂ and for N₂O to N₂ it was 1:1.Abbreviations BVH reduced benzyl viologen - MVH reduced methyl viologen - HOQNO 2-n-heptyl-4-hydroxyquinoline-N-oxide - CCCP carbonyl cyanide-m-chlorophenyl-hydrazone - DIECA diethyl dithiocarbamate - KCN potassium cyanide     

Cytokinin activity of N-phenyl-N′-(4-pyridyl)urea derivatives

We have synthesized 35 N-phenyl-N′-(4-pyridyl)urea derivatives and tested their cytokinin activity in the tobacco callus bioassay. Among them, N-phenyl-N′- (2-chloro-4-pyridyl)urea is highly active, the optimum concentration of which is lower than 4 × 10^?9 M (0.001 ppm), 3 compounds, i.e. N-(2-methylphenyl)-N′-(2-chloro-4-pyridyl)urea, N-(3-methylphenyl)-N′-(2-chloro-4-pyridyl)urea and N-(3-chlorophenyl)-N′-(2-chloro-4-pyridyl) urea are as active as N⁶-benzyladenine (concentration for optimum yield: 4.4 × 10^?8 M or 0.01 ppm), and N-phenyl-N′-(2-methyl-4-pyridyl)urea and N-(2-chlorophenyl)-N′-(2-chloro-4-pyridyl)urea are as active as N-phenyl-N′-(4-pyridyl)urea (concentration for optimum yield: 4.7 × 10^?7 M or 0.1 ppm), while the activity of the other 29 compounds are not so remarkable and 11 of them are almost or completely inactive.     

Methylated N-aryl chitosan derivative/DNA complex nanoparticles for gene delivery: Synthesis and structure–activity relationships

In this study, three kinds of methylated chitosan containing different aromatic moieties were synthesized by two steps, reductive amination and methylation, respectively. The chemical structures of all methylated derivatives, methylated N-(4-N,N-dimethylaminocinnamyl) chitosan chloride (MDMCMChC), methylated N-(4-N,N-dimethylaminobenzyl) chitosan chloride (MDMBzChC), and methylated N-(4-pyridinylmethyl) chitosan chloride (MPyMeChC) were characterized by ATR–FTIR and ¹H NMR spectroscopy. The complexes between the chitosan derivatives and plasmid DNA at different N/P ratios were characterized by gel electrophoresis, dynamic light scattering, and atomic force microscopic techniques. The smallest particle sizes of these complexes were obtained at N/P ratio of 5 and ranged from 95 to 124 nm while the zeta-potentials were in the range of 18–27 mV. Transfection efficiencies of these complexes were investigated by expression of the plasmid DNA encoding green fluorescence protein (pEGFP-C2) on human hepatoma cells (Huh 7 cells) compared to N,N,N-trimethyl chitosan chloride (TMChC). The rank of transfection efficiency was MPyMeChC > MDMBzChC > TMChC > MDMCMChC, respectively. The cytotoxicity of these complexes was also studied by MTT assay where the MPyMeChC complex exhibited less toxicity than other derivatives even at high N/P ratios. Therefore, MPyMeChC demonstrated potential as its safe and efficient gene carrier.     

The effects of experimentally altered gill chloride cell surface area on acid-base regulation in rainbow trout during metabolic alkalosis

To evaluate the role of the gill chloride cells in regulating metabolic alkalosis in rainbow trout (Oncorhynchus mykiss), the surface area of branchial chloride cells was altered experimentally using combined cortisol/ovine growth hormone injections. Long-term (10-day) treatment of fish with cortisol/ovine growth hormone caused an increase in the two-dimensional chloride cell fractional surface area when compared to uninjected fish (from 8.4 to 29.7%). This was the combined result of an increase in the size of individual cells (from 34.6 to 59.2 m²) and increased numbers of cells (from 2368 to 5006 cells · mm^-2). Metabolic alkalosis was induced by intra-arterial infusion of 140 mmol · l^-1 NaHCO₃; control fish were infused with 140 mmol · l^-1 NaCl. Blood pH and plasma [HCO₃ ^-] increased in both the untreated and the cortisol/ovine growth hormone-treated fish. However, the increases in pH (from 8.05 to 8.53) and [HCO₃ ^-] (from 5.9 to 22.2 mmol · l^-1) in the untreated fish were significantly greater than in the cortisol/ovine growth hormone-treated fish (pH increased from 7.78 to 8.11; [HCO₃ ^-] increased from 5.5 to 13.9 mmol · l^-1). In all fish, NaHCO₃ infusion elicited an increase in the rate of branchial basic equivalent excretion (acidic equivalent uptake) which, in turn, was caused by decreases and increases in branchial Na⁺ uptake and Cl^- uptake, respectively. In the untreated fish, there was a pronounced increase (75%) in chloride cell surface area during NaHCO₃ infusion. The attenuation of the metabolic alkalosis during HCO₃ ^- infusion in the cortical/ovine growth hormone-treated fish was caused, at least in part, by an enhancement of branchial basic equivalent excretion. In these fish that already displayed a proliferation of chloride cells, there was no further increase in chloride cell surface area. The changes in Na⁺ influx and Cl^- influx were quantitatively similar during NaHCO₃ infusion in both groups. This suggests that the greater rate of base excretion in the cortisol/ovine growth hormone-treated fish was caused by a greater percentage of Cl^- uptake being coupled to HCO₃ ^- excretion and less to Cl^- excretion (Cl^- exchange diffusion).Abbreviations Amm total ammonia - bw body weight - CC chloride cell - CCFA chloride cell fractional area - cort/oGH cortisol/ovine growth hormone - dpm disintegrations per minute - J ^Amm net flux of total ammonia - J _in unidirectional influx - J _inCl^- chloride ion uptake - J _inNa⁺ sodium ion uptake - J _netH⁺ net acidic equivalent flux - J ^TA net flux of titrable alkalinity - MS 222 ethyl-m-aminobenzoate - oGH ovine growth hormone - PVC pavement cell - SEM scanning electron microscope - TA titrable alkalinity     

Putative role of the adenosine A3 receptor in the antiproliferative action of N 6-(2-isopentenyl)adenosine

We tested a panel of naturally occurring nucleosides for their affinity towards adenosine receptors. Both N ⁶-(2-isopentenyl)adenosine (IPA) and racemic zeatin riboside were shown to be selective human adenosine A₃ receptor (hA₃R) ligands with affinities in the high nanomolar range (K _i values of 159 and 649 nM, respectively). These values were comparable to the observed K _i value of adenosine on hA₃R, which was 847 nM in the same radioligand binding assay. IPA also bound with micromolar affinity to the rat A₃R. In a functional assay in Chinese hamster ovary cells transfected with hA₃R, IPA and zeatin riboside inhibited forskolin-induced cAMP formation at micromolar potencies. The effect of IPA could be blocked by the A₃R antagonist VUF5574. Both IPA and reference A₃R agonist 2-chloro-N ⁶-(3-iodobenzyl)adenosine-5′-N-methylcarboxamide (Cl-IB-MECA) have known antitumor effects. We demonstrated strong and highly similar antiproliferative effects of IPA and Cl-IB-MECA on human and rat tumor cell lines LNCaP and N1S1. Importantly, the antiproliferative effect of low concentrations of IPA on LNCaP cells could be fully blocked by the selective A₃R antagonist MRS1523. At higher concentrations, IPA appeared to inhibit cell growth by an A₃R-independent mechanism, as was previously reported for other A₃R agonists. We used HPLC to investigate the presence of endogenous IPA in rat muscle tissue, but we could not detect the compound. In conclusion, the antiproliferative effects of the naturally occurring nucleoside IPA are at least in part mediated by the A₃R.     

Studies on Synthesis and Structure of O-β-D-Ribofuranosyl(1″→2′)-ribonucleosides and Oligonucleotides♣

Abstract

Minor nucleosides found in several eukaryotic initiator tRNAs_i ^Met, O-β-D-ribofuranosyl(1″→2′)adenosine and -guanosine (Ar and Gr), as well as their pyrimidine analogues, were obtained from N-protected 3′,5′-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)ribonucleosides and 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose in the presence of tin tetrachloride in 1,2-dichloroethane. A crystal structure has been solved for 2′-O-ribosyluridine. The 3′-phosphoramidites of protected 2′-O-ribosylribonucleosides were prepared as the reagents for 2′-O-ribofuranosyloligonucleotides synthesis. O-β-D-Ribofuranosyl(1″→2′)adenylyl(3′→5′)guanosine (ArpG) was obtained and its structure was analysed by NMR spectroscopy.

     

Interaction of gangliosides with plasma low density lipoproteins

The role of gangliosides in the reception of low density lipoproteins (LDL) was studied using as targets mouse ascites hepatoma 22a (MAH) cells which bind LDL through a specific high affinity receptor. Low density lipoprotein binding and uptake by MAH cells decreased after brief treatment of the cells with neuraminidase to partially remove surface sialic acid residues. The LDL uptake capability of the neuraminidasetreated MAH cells was fully restored after incorporation of exogeneous G_M1- and G_D1a-gangliosides into the cell surface. In contrast, free (extracellular) gangliosides inhibited LDL uptake by native MAH cells. This inhibitory effect was seen at ganglioside concentrations corresponding to the ganglioside content of serum and was most pronounced with gangliosides whose sialic acids were linked to a terminal galactose residue (G_M3, G_D1a, G_T1b) but was smaller or absent with gangliosides whose sialic acids were attached to an internal galactose (G_M1, G_M2). The binding of gangliosides to LDL was structure and concentration dependent, saturable and trypsin sensitive. The LDL-ganglioside interaction was further investigated by steady state fluorescence spectroscopy. Changes in the LDL fluorescence polarization were observed with as little as 0.01 M concentrations of the gangliosides. The magnitude and nature of the effect depended on the type of ganglioside. We conclude that the LDL surface possesses sites recognizing specific carbohydrate sequences of glycoconjugates and that changes in the cell surface concentrations of sialic acids significantly modulate the LDL uptake. It is postulated that shedding of gangliosides into the blood stream may be a factor involved in regulation of cholesterol homeostasis.Abbreviations MAH mouse ascites hepatoma 22a - LDL low density lipoprotein - ASM anthrylvinyl-labeled sphingomyelin [N-12-(9-anthryl-trans-dodecanoyl-sphingosine-1-phosphocholine] - RITC rhodamine isothiocyanate. The designation of gangliosides follows the IUPAC-IUB recommendation [1]: G_M3, II³NeuAc-LacCer, II³-N-acetylneuraminosyllactosylceramide - G_M2 II³-NeuAc-GgOse₃Cer, II³-N-acetylneuraminosylgangliotriaosylceramide - G_M1 II³-NeuAc-GgOse₄Cer, II³-N-acetylneuraminosylgangliotetraosylceramide - G_D1a, II³ IV³(NeuAc)₂-GgOse₄Cer, II³, IV³-di(N-acetylneuraminosyl)gangliotetraosylceramide - G_T1b II³(NeuAc)₂, IV³ NeuAc-GgOse₄Cer, II³-di-N-acetylneuraminosyl, IV³-N-acetylneuraminosylgangliotetraosylceramide     

Interactions of glycolate-, HCO 3 - -, Cl--, and H+-balance of Scenedesmus obliquus

Excretion and absorption of glycolate by young cells of Scenedesmus obliquus (Turp.) Krüger strain D₃ grown synchronously with 2% CO₂ was compared after no pretreatment with air (CO₂-adapted) or after a 2 h adaptation to normal air (0.03% CO₂) (air-adapted). At 21% O₂, excretion occurred only from CO₂-adapted cells at high pH (pH 8.0). Under conditions where no excretion occurred, external glycolate (0.2 mM) was taken up by both air-and CO₂-adapted cells at a much faster rate at pH 5 than at pH 8. The uptake was accompanied by an apparent stoichiometric uptake of H⁺. CO₂-adapted algae exhibited high uptake rates that were even higher in the dark than in the light. Air-adapted algae showed high uptake rates in the light but only minimal uptake in the dark. The uptake rate was decreased to about 1/3 with 5% CO₂, except with CO₂-adapted cells in the light, in which a slight stimulation occurred. Cl^- ions inhibited glycolate uptake by air-adapted cells in the light; conversely, light-stimulated Cl^- uptake of these cells was inhibited by glycolate. A hypothesis is discussed according to which the internal pH regulates the uptake and release of Cl^-, HCO ₃ ^- , and glycolate.Abbreviations DCMU 3-(3,4 dichlorophenyl)-1, 1-dimethyl urea - FCCP carbonyl cyanide p-trifluoro-methoxyphenylhydrazone - HEPES 2-(4-(2-hydroxyethyl)-piperazinyl) ethanesulfonic acid - HPMS -hydroxypyridinemethanesulfonate - MES 2-morpholinoethanesulfonic acid - PCV packed cell volume     

N-andO-glycosylation of glycoprotein C synthesized by Herpes simplex virus type 1-infected ricin resistant cells

The progeny of Herpes simplex virus type 1 (HSV-1) grown in ricin-resistant 14 cells (Ric^R14) lackingN-acetylglucosaminyltransferase I was released in the extracellular medium at a very low rate. By using a monoclonal antibody immobilized on Sepharose we purified from HSV-1-infected Ric^R14 cells a viral glycoprotein (gC), which carries bothN-andO-linked oligosaccharides. Glycopeptides obtained from [³H]mannoselabeled gC by Pronase digestion were entirely susceptible to endo--N-acetylglucosaminidase H, and the major oligosaccharide released was Man₄GlcNAc. The accumulation of this high-mannose species was related to the enzymic defect of the host cells and to the long retention of the viral glycoprotein within the cells. The extent ofO-glycosylation evaluated in [¹⁴C]glucosamine-labeled gC from Ric^R14 cells as compared to that of gC from wild type cells did not appear to be significantly modified.Abbreviations Con A concanavalin A - BHK cells baby hamster kidney cells - HSV Herpes simplex virus     

Significance of treatment interval and DNA repair in the enhancement of viral transformation by chemical carcinogens and mutagens

Treatment of Syrian hamster embryo cells with diverse classes of chemical carcinogens enhanced transformation by a carcinogenic simian adenovirus, SA7. Optimal enhancement was a function of time of chemical addition in relation to time of virus addition and cell transfer. Aflatoxin B₁ (AFB₁) and the polycyclic hydrocarbons, benzo(a)pyrene (B(a)P), 3-methylcholanthrene (MCA), and 7,12-dimethylbenz(a)anthracene (DMBA) enhanced SA7 transformation when added prior to virus, but inhibited transformation when added after virus adsorption and cell transfer. The enhancement of SA7 transformation was maximal when cytosine arabinoside, caffeine and 6-acetoxy-benzo(a)pyrene (6-ac-B(a)P) were added after virus, but minimal when added before virus. A third class of chemicals, including β-propiolactone (β-PL), methyl methanesulfonate (MMS), N-acetoxy-2-acetylaminofluorene (Ac-AAF), N-methyl-N′-nitro-N-nitrosoguanidine (MNNG), and methylazoxymethanol acetate (MAM-ac), enhanced SA7 transformation added before, or after, virus inoculation and cell transfer. All chemicals, which induced changes in DNA sedimentation in alkaline sucrose gradients and unscheduled DNA (repair) synthesis in hamster cells, increased the frequency of SA7 transformation. However, several chemicals such as dibenz(a,h)anthracene (DB(a,h)A), benzo(e)pyrene (B(e)P), cytosine arabinoside, and caffeine enhanced SA7 transformation but did not induce DNA sedimentation changes or repair. Chemicals that cause DNA damage, which can be repaired by hamster cells, may enhance viral transformation by providing additional sites for integration of viral DNA during the repair process. Chemicals that apparently do not induce DNA repair synthesis may enhance viral transformation by incorporation of viral DNA into gaps in cell DNA at sites of unrepaired damage during scheduled DNA synthesis.     

Studies of nucleosides and nucleotides.: LVIII. Deamination of adenosine analogs with calf intestine adenosine deaminase

Several synthetic adeonosine analogs: 8-fluoro-, 8-azido-, 8-iodo-, 8-methylthioadenosine; 8-bromo-2′-deoxyadenosine, 8-bromoxylofuranosyladenine, 5′-benzoly-8-bromoadenosine; 8,2′-S-, 8,2′-O-, 8,2′-NH-, 8,2′-N-CH₃-, 8,3′,-S-, 8,3′-O-, 8,5′-S- and 8,5′O-cycloadenosine; 1-deaza- and 3-deazaadenosine, as well as tubercidine (7-deazaadenosine), were tested as substrates of calf intestine adenosine deaminase.It was found that the adenine base of adenosine should be in the range φ_rmCN = 0–120° (anti to syn-anti) and 8-fluoroadenosine was hydroylzed very slowly. The purine base should have N¹, N³ or N⁷ atoms for the hydrolysis and only 1-deazaadenosine revealed an inhibitory effect toward the hydrolysis of adenosine.5′-OH group should be in the position of S-configuration and must not be substituted.     

A broad spectrum anticancer nucleoside with selective toxicity against human colon cells in vitro

2′,3′-Bis-O-tert-butyldimethylsilyl-5′-deoxy-5′-[N-(methylcarbamoyl)amino]-N⁶-(N-phenylcarbamoyl)adenosine, a new member of the N⁶,5′-bis-ureidoadenosine class of anticancer nucleosides, is found to exhibit broad spectrum antiproliferative activity. A majority of the cell lines in the NCI-60 are inhibited with an average GI₅₀ = 3.13 μM. Selective toxicity against human colon cancer cell lines (COLO 205, HCC-2998, HCT-116, HT29, KM12) was also exhibited (LC₅₀’s = 6-10 μM).     

Synthesis and urease inhibitory potential of benzophenone sulfonamide hybrid in vitro and in silico

This study deals with the synthesis of benzophenone sulfonamides hybrids (1–31) and screening against urease enzyme in vitro. Studies showed that several synthetic compounds were found to have good urease enzyme inhibitory activity. Compounds 1 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-nitrobenzenesulfonohydrazide), 2 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-3′′-nitrobenzenesulfonohydrazide), 3 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-methoxybenzenesulfonohydrazide), 4 (3′′,5′′-dichloro-2′′-hydroxy-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 6 (2′′,4′′-dichloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 8 (5-(dimethylamino)-N′-((4-hydroxyphenyl)(phenyl)methylene)naphthalene-1-sulfono hydrazide), 10 (2′′-chloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 12 (N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide) have found to be potently active having an IC₅₀ value in the range of 3.90–17.99?µM. These compounds showed superior activity than standard acetohydroxamic acid (IC₅₀?=?29.20?±?1.01?µM). Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease enzyme. Structures of all the synthetic compounds were elucidated by ¹H NMR, ¹³C NMR, EI-MS and FAB-MS spectroscopic techniques.     

Synthesis,structures and urease inhibitory activity of cobalt(III) complexes with Schiff bases

A series of new cobalt(III) complexes were prepared. They are [CoL¹(py)₃]·NO₃ (1), [CoL²(bipy)(N₃)]·CH₃OH (2), [CoL³(HL³)(N₃)]·NO₃ (3), and [CoL⁴(MeOH)(N₃)] (4), where L¹, L², L³ and L⁴ are the deprotonated form of N′-(2-hydroxy-5-methoxybenzylidene)-3-methylbenzohydrazide, N′-(2-hydroxybenzylidene)-3-hydroxylbenzohydrazide, 2-[(2-dimethylaminoethylimino)methyl]-4-methylphenol, and N,N′-bis(5-methylsalicylidene)-o-phenylenediamine, respectively, py is pyridine, and bipy is 2,2′-bipyridine. The complexes were characterized by infrared and UV–Vis spectra, and single crystal X-ray diffraction. The Co atoms in the complexes are in octahedral coordination. Complexes 1 and 4 show effective urease inhibitory activities, with IC₅₀ values of 4.27 and 0.35 μmol L⁻¹, respectively. Complex 2 has medium activity against urease, with IC₅₀ value of 68.7 μmol L⁻¹. While complex 3 has no activity against urease. Molecular docking study of the complexes with Helicobacter pylori urease was performed.     

A General Synthetic Method of 5-Carboranyluracil Nucleosides with Potential Antiviral Activity and use in Neutron Capture Therapy

Abstract

Previous biochemical and pharmacological studies indicated that 5-o-carboranyl-2′-deoxyuridine is a lead candidate for boron neutron capture therapy. This prompted the development of a rapid and stereoselective N ¹-glycosylation reaction of silylated 5-o-carboranyluracil with a variety of protected sugars. The key intermediate, 5-o-carboranyluracil (6), was prepared from 5-iodouracil in six steps. A novel coupling procedure of the 2,4-dimethoxy-5-ethynylpyrimidine (4) with decaborane without activator was used. Silylated 6 was coupled with a variety of carbohydrates under mild conditions to produce several carborane containing nucleosides. In each case, the stereochemistry and stereoselectivity of the glycosylation reaction was not affected by the presence of the carborane at the 5-position of the uracil and produced exclusively closo [closo-1,2-C₂B₁₀H₁₂ cage] nucleosides. This was confirmed by X-ray structure determination of racemic 5-carboranyl-2′,3′-dideoxy-3′-thiauridine. This compound demonstrated an anti-conformation with the oxathiolane ring in a pseudo C-2′-endo conformation. The toxicity profile of the new compounds and their precursors was determined in three cell culture systems, two of human origin (PBM and CEM cells) and one of monkey origin (Vero cells). The compounds were also evaluated for their potential antiviral activity against human immunodeficiency virus and herpes simplex virus in vitro. 5-o-Carboranyl-xylofuranosyluracil (12) demonstrated low toxicity in culture and in mice.