Synthesis of novel phosphorylated guanidine derivatives from cyanamide and their anti-inflammatory activity. (49/62)

A series of novel guanidine derivatives were synthesized in three steps and their anti-inflammatory activities in vitro and in vivo evaluated. 2-Aminopyridin-3-ol (1) was reacted with thiophosphoryl chloride (2) to give a monochloride (3). It was further reacted with cyanamide to afford the corresponding cyanamine (4), which was subsequently reacted with different heterocyclic amines to form the title compounds (5a-l). The substituent in the guanidine function affected the potency of anti-inflammatory activity. The compounds having benzothiazole, fluorophenyl, and piperazinyl moieties enhanced the anti-inflammatory activity.  (+info)

Inhibition of tomato (Solanum lycopersicum L.) root growth by cyanamide is not always accompanied with enhancement of ROS production. (50/62)

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9-cis retinoic acid is the ALDH1A1 product that stimulates melanogenesis. (51/62)

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Effects of cyanamide, an aldehyde dehydrogenase type 2 inhibitor, on glyceryl trinitrate- and isosorbide dinitrate-induced vasodilation in rabbit excised aorta and in anesthetized whole animal. (52/62)

The contribution of aldehyde dehydrogenase type 2 (ALDH2) to bioactivation of glyceryl trinitrate (GTN) and isosorbide dinitrate (ISDN) was systematically examined in excised rabbit aorta and anesthetized whole animal with cyanamide, an ALDH2 inhibitor. In excised aortic preparation, the degree of inhibition by cyanamide in GTN-induced vasorelaxation (concentration ratio, calculated as EC(50) in the presence of cyanamide/EC(50) in the absence of cyanamide; 5.61) was twice that in ISDN-induced relaxation (2.78). However, the degree of inhibition by cyanamide, as assessed by the dose ratio (as described above, but calculated with doses) in anesthetized rabbits was 2.29 in GTN-induced hypotension (assessed by area under the curve (AUC) of 50 mmHg.min) and 7.68 in ISDN-induced hypotension. Thus, the inhibitor was 3 times more potent in ISDN-induced hypotension, a finding in conflict with to that obtained in excised aortic preparation. The rate of increase in plasma nitrite (NO(2)(-)) concentration at certain hypotensive effect (50 mmHg.min of AUC) in the presence and absence of cyanamide (DeltaNO(2)(-) ratio) was larger in ISDN-induced hypotension (15.01) than in GTN-induced hypotension (3.28). These results indicate that the bioactivation pathway(s) of GTN is ALDH2-dependent in aortic smooth muscle, while ADLH2-independent mechanism(s) largely take place in the whole body. In contrast, the activation mechanism(s) of ISDN is largely ALDH2-dependent in both aortic smooth muscle and whole body. Plasma NO(2)(-) may be derived from pathways other than the cyanamide-sensitive metabolic route.  (+info)

Possible role of acetyl-CoA in the inhibition of CoA biosynthesis by ethanol in rats. (53/62)

Ethanol, both administered to rats in vivo and added to cultured hepatocyte incubations, inhibits the conversion of [14C]pantothenate to coenzyme A (CoA). Data suggesting that the inhibition by ethanol involves its oxidation to acetate were obtained with rat hepatocytes maintained in primary culture. Ethanol, acetaldehyde and acetate were approximately equally effective inhibitors of [14C]pantothenate conversion to CoA (46-71%) and had no effect on uptake of [14C]pantothenate by hepatocytes. In the presence of saturating levels of acetate, acetaldehyde had no additional inhibitory effect. Cyanamide and diethyldithiocarbamate decreased the inhibition by acetaldehyde at the same concentration (10 microM), which saturated their ability to inhibit acetaldehyde oxidation. Studies with an isolated pantothenate kinase preparation showed that, of the ethanol metabolites, only acetyl-CoA was an effective inhibitor. Acetate and butyrate, which were both inhibitors of [14C]pantothenate conversion to CoA, increased the acetyl-CoA and decreased the free, unacylated CoA (CoASH) content of the cultured hepatocytes. The data were consistent with a mechanism for the inhibitory effect of ethanol that involves inhibition of pantothenate kinase by acetyl-CoA, but did not exclude a possible role of additional regulatory factors.  (+info)

Effect of aldehyde dehydrogenase inhibitors on the ex vivo sensitivity of human multipotent and committed hematopoietic progenitor cells and malignant blood cells to oxazaphosphorines. (54/62)

The ex vivo sensitivity of human multipotent and committed hematopoietic progenitor cells and several cultured human malignant blood cell lines to analogues of "activated" cyclophosphamide, namely, 4-hydroperoxycyclophosphamide and mafosfamide, and to phosphoramide mustard was quantified with and without concurrent exposure to an inhibitor of aldehyde dehydrogenase activity, namely, disulfiram, cyanamide, diethyldithiocarbamate, or ethylphenyl(2-formylethyl)phosphinate. Inhibitors of aldehyde dehydrogenase activity potentiated the cytotoxic action of 4-hydroperoxycyclophosphamide and mafosfamide toward all of the hematopoietic progenitors; they did not potentiate the cytotoxic action of phosphoramide mustard toward these cells. Potentiation of the cytotoxic action of mafosfamide toward cultured human malignant blood cells was minimal. Spectrophotometric assay revealed little NAD-linked aldehyde dehydrogenase activity present in the cultured human tumor cell lines as compared to that found in normal mouse liver or oxazaphosphorine-resistant L1210 cells. Cellular aldehyde dehydrogenases are known to catalyze the oxidation of 4-hydroxycyclophosphamide/aldophosphamide, the major intermediate in cyclophosphamide bioactivation, to the relatively nontoxic acid, carboxyphosphamide. Thus, our findings indicate that human multipotent hematopoietic progenitor cells contain the relevant aldehyde dehydrogenase activity, the relevant activity is retained upon differentiation to progenitors committed to the megakaryocytoid, granulocytoid/monocytoid, and erythroid lineages, and the relevant activity may be lost or diminished upon transformation of hematopoietic progenitors to malignant cells.  (+info)

Concentration-time profiles of ethanol and acetaldehyde in human volunteers treated with the alcohol-sensitizing drug, calcium carbimide. (55/62)

1. The disposition kinetics of ethanol and its toxic metabolite acetaldehyde were investigated in 10 healthy male volunteers who ingested 0.25 g kg-1 ethanol after an overnight fast. This dose of ethanol was given 2 h after they swallowed a tablet of either calcium carbimide CC (50 mg), a potent inhibitor of low Km aldehyde dehydrogenase (ALDH), or placebo according to a single-blind crossover design. 2. The pulmonary blood concentrations of ethanol and acetaldehyde were estimated indirectly by means of a gas chromatographic method modified for analysis of end-expired breath. This non-invasive sampling technique allowed replicate determinations at 15 min intervals. 3. The distribution volume of ethanol (V) was 0.64 +/- 0.023 1 kg-1 after CC and 0.68 +/- 0.026 l kg-1 after placebo treatment (P greater than 0.05). The zero order slope of the blood-ethanol decay profile (ko) decreased by about 5% when low Km ALDH was inhibited. The elimination of ethanol from the body (V X ko) was 1.9 +/- 0.051 mmol kg-1 h-1 after CC compared with 2.11 +/- 0.056 mmol kg-1 h-1 in placebo control experiments (P less than 0.001). The area under the ethanol concentration time curve (0----180 min) increased after CC treatment implying a change in clearance. 4. The disposition of acetaldehyde was markedly different in subjects pretreated with CC. The peak blood-concentrations, estimated by analysis of breath, ranged from 40-242 mumol l-1 compared with 1.7-6.5 mumol l-1 after placebo.(ABSTRACT TRUNCATED AT 250 WORDS)  (+info)

Mode of mutagenic action of methylnitrosocyanamide, a potent carcinogen. (56/62)

A potent carcinogen, methylnitrosocyanamide was used to induce revertants in a strain of Escherichia coli carrying an amber mutation in a gene for tryptophan (trp) biosynthesis and an ochre mutation in a gene for alkaline phosphatase biosynthesis. Trp+ revertants were purified and classified into seven categories based on their ability to support the growth of particular nonsense mutants of phage lambda and on their content of alkaline phosphatase. About 90% of the Trp+ revertants induced by methylnitrosocyanamide were due to mutations in suppressor genes, and 85% of the suppressor mutations occurred in gene supE. Intragenic reversion cannot occur by a GC leads to AT base substitution mutation, whereas this is the obligate mode of mutation in gene supE. We conclude that methylnitrosocyanamide preferentially induces GC leads to AT transition mutations but that other base substitution mutations are also induced at about 10% of this frequency. N-Methyl-N-nitrosourea and, particularly, N-methyl-N'-nitro-N-nitrosoguanidine also preferentially induce GC leads to AT transition mutations.  (+info)