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At least 343 records · Page 19Linked to original sources
PubMed2000

Convenient preparation of O-linked polymer-bound N-substituted hydroxylamines, intermediates for synthesis of N-substituted hydroxamic acids.

[reaction: see text] An efficient procedure for preparation of O-linked polymer-bound N-substituted hydroxylamines by reduction of resin-bound oximes with borane.pyridine complex in the presence of dichloroacetic acid is reported. Other reducing systems commonly used for imine or oxime reduction were ineffective, including borane.pyridine in the presence of acetic acid. Oximes derived from a variety of aromatic and aliphatic aldehydes and ketones were successfully reduced. The N-substituted products were acylated and cleaved from resin to afford N-substituted hydroxamic acids.

Journal Article↗
PubMed1998

Cyclic hydroxamic acid inhibitors of prostate cancer cell growth: selectivity and structure activity relationships.

BACKGROUND: Clinical symptoms of prostatitis, prostatodynia, and benign prostatic hyperplasia are relieved by the pollen extract cernilton, and the water-soluble fraction of this extract selectively inhibits growth of some prostate cancer cells. A cyclic hydroxamic acid, DIBOA, has been isolated from this extract and mimics its cell growth-inhibitory properties, but the specificity of DIBOA for inhibition of prostate cell growth has not been reported. METHODS: The in vitro growth inhibitory effects of DIBOA and nine structurally related compounds on DU-145 prostate cancer cells, MCF-7 breast cancer cells, and COS-7 monkey kidney cells were determined by treatment of the cells with various concentrations of the compounds for 2-6 days. RESULTS: The compounds exhibited a wide range of potencies, but none of them exhibited selective inhibition of DU-145 cell growth. MCF-7 cells were more sensitive to DIBOA than either DU-145 cells or COS-7 cells. 3,4-dihydroquinoline-2(1H)-one, compound (4), and 1-hydroxy-6-chloro-3,4-dihydroquinolin-2(1H)-one, compound (7), selectively inhibited MCF-7 cell growth at a concentration of 10 micrograms/ml. 1-hydroxy-3,4-dihydroquinolin-2(1H)-one, compound (3), and compound 7 were the most potent inhibitors of DU-145 cell growth. Treatment of DU-145 cells with 3 (100 micrograms/ml) substantially decreased the number of viable cells within 2 days, and no viable cells remained in the culture by day 4. CONCLUSIONS: It is unlikely that DIBOA, compound (1), is responsible for the selective growth inhibition of prostate cancer cells by the water-soluble fraction of the pollen extract cernilton. Cell morphology results indicate that the growth-inhibitory effects of DIBOA and structurally related agents on DU-145 cells are due to their ability to cause cell death.

Benzoxazines↗
PubMed2002

Inhibition of potato lipoxygenase by linoleyl hydroxamic acid: kinetic and EPR spectral evidence for a two-step reaction.

The reaction mechanism of an electrophoretically pure potato tuber lipoxygenase (ptLOX) was studied by EPR spectroscopy. An EPR spectrum of the 'native' ptLOX recorded at 4.5+/-0.5 K showed signals of a high-spin (pseudo) axial Fe(3+) with a g-value of approx. 6.3+/-0.1 with a shoulder at g=5.9+/-0.1, and a rhombic Fe(3+) signal at g=4.35+/-0.05. When the enzyme was treated with a 2-fold molar excess of 13(S)-hydroperoxyoctadecadienoic acid [13(S)-HPODE], a 3-fold increase in the integral intensity of the g=6.3 signal was observed, indicating that 25% of the native ptLOX iron was in ferrous state. The positional isomer 9(S)-HPODE caused similar spectral changes. Therefore the catalytic centre of ptLOX appears to accommodate both positional isomers of linoleic acid hydroperoxides in a manner that ensures proper alignment of their hydroperoxy groups with the iron centre of the enzyme. Treatment of the Fe(3+)-ptLOX form with a 3-fold molar excess of linoleyl hydroxamic acid (LHA) completely quenched the g=6.3 signal. Concurrently, a dramatic increase in the signal at g=4.35 was detected, which was attributed to a newly formed LHA-Fe(3+)-ptLOX complex. The spectral characteristics of the complex are similar to those of a 4-nitrocatechol-Fe(3+)-ptLOX complex. From these observations, we conclude that LHA did not reduce Fe(3+) to Fe(2+), but rather formed a LHA-Fe(3+)-ptLOX complex. Formation of such a complex may be responsible for the inhibitory activity of LHA, at least in the initial stages of enzyme inhibition. A prolonged 15 min incubation of the complex at 23+/-1 degrees C led to the partial quenching of the g=4.35 signal. The quenching is attributed to the reduction of Fe(3+)-ptLOX by LHA, with concomitant formation of its oxidation product(s). A kinetic scheme for the inhibition is proposed.

Electron Spin Resonance Spectroscopy↗
PubMed1984

Reaction of cyanide with hydroxamic acid iron complexes to distinguish trihydroxamates from simple monohydroxamates.

At high pH primary hydroxamic acid-iron complexes react rapidly with potassium cyanide to yield a deep blue iron complex. Secondary, or N-substituted, monohydroxamic acid-iron complexes also react with loss of the red color typical of these complexes but with no formation of the blue product. Under the same conditions, trihydroxamates do not react at a significant rate. The blue complex is similar in many respects to the previously described Fe(CN)5NO3- but is noteworthy in its stability to oxidation and extremely high pH. Lack of formation of the blue complex with secondary hydroxamates is attributed to the absence of inorganic hydroxylamine so that the nitrosyl group cannot be formed. Lack of reactivity of siderophore trihydroxamates is due to the much greater stability of their iron complexes. The reaction is a simple, convenient method of distinguishing primary, secondary, and siderophore trihydroxamic acids.

Chemical Phenomena↗
PubMed2003

Sulfonate ester hydroxamic acids as potent and selective inhibitors of TACE enzyme.

Sulfonamide hydroxamate derivatives of anthranilic acids are known to be potent inhibitors of cell-free TACE enzyme. However, compounds of this structural class with both high potency and high selectivity for TACE over matrix metalloproteinases (MMPs) are uncommon. Replacement of the sulfonamide functionality with an isosteric sulfonate ester has resulted in a series of sulfonate ester hydroxamates, 2a-e, with excellent activity against TACE and excellent selectivity over MMP-1 and MMP-13. Although compounds 2a-e possess good permeability in a PAMPA assay, they are only weakly active as inhibitors of lipopolysaccharide (LPS)-stimulated tumor necrosis factor (TNF) production in human monocytic THP-1 cells. Protein binding affinity also does not predict the lack of cellular activity for these analogs.

ADAM Proteins↗