2-Deacetylchelocardin: A Degradation Product of Chelocardin

1975 ◽  
Vol 53 (10) ◽  
pp. 1434-1441 ◽  
Author(s):  
Daniel T. W. Chu ◽  
D. L. Garmaise ◽  
E. Bernstein
Keyword(s):  
Chemical Transformation ◽  
Degradation Product ◽  
Hydroxyl Group ◽  
Acetyl Group ◽  
Hydrolysis Of

A novel chemical transformation is described in which chelocardin 1, under normal ketalization conditions, is converted with elimination of the 2-acetyl group, to the bisdioxolane 2. Hydrolysis of 2 yields 2-deacetylchelocardin 4. The properties of the tricarbonylmethane system in 1 and of the 1,3-cyclohexanedione system in 4 are found to be profoundly modified by the presence of the 4-amino and the 12a-hydroxyl group.

The cardiac glycosides of Gomphocarpusf ruticosus R.Br. I. Afroside

1956 ◽  
Vol 9 (4) ◽  
pp. 497 ◽  
Author(s):  
TR Watson ◽  
SE Wright
Keyword(s):  
Simple Structure ◽  
Lactone Ring ◽  
Aldehyde Group ◽  
Hydroxyl Group ◽  
Naturally Occurring ◽  
Ring Junction ◽  
Infra Red ◽  
Free Aldehyde ◽  
Acetyl Group ◽  
Hydrolysis Of

Afroside, C29H42O9, is a new cardiac glycoside which has been obtained from Gomphocarpus fruticosus R.Br. It contains a carbonyl (aldehyde) group at C10, and a secondary hydroxyl group in the nucleus, which has been placed provisionally at position C11. On the basis of the available evidence, afroside appears to consist of a mixture of the isomeric free aldehyde and the 19-11 cyclic hemiacetal forms. Of these substances, the cyclic hemiacetal form is the only one which has been isolated in pure condition (afroside B). Acetylation of afroside produced a triacetate, C35H46O12.H2O, which is identical with that obtained by the acetylation of afroside B. Reduction of afroside with sodium borohydride produces afrosidol, C29H44O9, which shows no evidence for a carbonyl group at C10. Hydrolysis of afroside produces α-anhydroafrogenin, C23H28-30O5.H2O, which forms a monoacetate, C25H32O7.H2O. The infra-red spectra of these compounds show the presence of a saturated γ-lactone ring in the structure of the nucleus, besides the normal Δα-β-γ-lactone ring at C17 (1786, 1755, 1633 cm-1). Acetyl-α-anhydroafrogenin also shows an intense absorption band of simple structure at 1238 cm-1, which indicates an equatorially orientated acetyl group at C3. As all the naturally occurring cardiac aglycones of known structure have a β-orientated hydroxyl group at C3, for the substituent in this position to be equatorial, the A/B ring junction is probably trans. Hydrolysis of afrosidol produces α-anhydroafrogenol, C23H32O5.H2O, which forms a diacetate, C27H36O7.H2O. The infra-red spectrum of α-anhydroafrogenol shows no evidence of the saturated y-lactone ring which is present in the structure of α-anhydroafrogenin.

DC Polarographic and Spectrophotometric Determination of Ampicillin Capsules

1980 ◽  
Vol 63 (5) ◽  
pp. 1049-1051
Author(s):  
Juan A Squella ◽  
Luis J Nunez-Vergara ◽  
Maximo Aros
Keyword(s):  
Absorption Band ◽  
Spectrophotometric Determination ◽  
Degradation Product ◽  
Uv Absorption ◽  
Acidic Hydrolysis ◽  
Average Recovery ◽  
Polarographic Wave ◽  
Spectrophotometric Methods ◽  
Hydrolysis Of

Abstract Polarographic and spectrophotometric methods are proposed for the determination of ampicillin in capsules. Acidic hydrolysis of ampicillin with 1% HCHO in 0.3N HCl yields a degradation product identified as 2-hydroxy-3-phenyl-6-methylpyrazine. This compound has a well defined UV absorption band at 380 nm and a polarographic wave at –0.55 V vs SCE, which can be used for analytical purposes. Individual capsule assays, composite assays, and recovery studies are described. The average recovery values and standard deviations (SD) for UV and polarographic determinations were 99.20% (SD 0.95) and 100.85% (SD 1.09), respectively

scholarly journals A Degradation Product from Hydrolysate of Imipenem with Imis Broad-Spectrum Inhibits Metallo-β-Lactamases

2020 ◽  
Vol 13 (10) ◽  
Author(s):  
Ying Ge ◽  
Li-Wei Xu ◽  
Jian-Bin Zhen ◽  
Cheng Chen ◽  
Miao Lv ◽  
...  
Keyword(s):  
Broad Spectrum ◽  
Degradation Product ◽  
Substrate Inhibition ◽  
Resistant Bacteria ◽  
Drug Resistant ◽  
Antibiotic Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Leaving Group ◽  
Ic50 Values ◽  
Hydrolysis Of

Background: Infections caused by metallo-β-lactamases (MβLs)-producing antibiotic-resistant bacteria pose a severe threat to public health. The synergistic use of current antibiotics in combination with MβL inhibitors is a promising therapeutic mode against these antibiotic-resistant bacteria. Objectives: The study aimed to probe the inhibition of MβLs and obtain the active component, P1, in the degradation product after imipenem was hydrolyzed by ImiS. Methods: The hydrolysis of two carbapenems with MβL ImiS was monitored by UV-Vis in real-time, and the degradation product from the leaving group produced after imipenem was hydrolyzed (but not for faropenem) was purified by HPLC to give one component, P1. Results: Kinetic assays revealed that P1 exhibited a broad-spectrum inhibition against VIM-2, NDM-1, ImiS, and L1, from three sub-classes of MβLs, with IC50 values of 8 - 32, 13.8 - 29.3, and 14.2 - 19.2 µM, using imipenem, cefazolin, and nitrocefin as substrates, respectively. Also, P1 showed synergistic antibacterial efficacy against drug-resistant Escherichia coli producing VIM-2, NDM-1, ImiS, and L1, in combination with antibiotics, restoring 16 to 32-fold and 32 to 128-fold efficacies of imipenem and cefazolin, respectively. Spectroscopic and Ellman's reagent analyses suggested that P1, a mercaptoethyl-form imidamide, is a mechanism-based inhibitor, while faropenem has no substrate inhibition, due to the lack of a leaving group. Conclusions: This work reveals that the hydrolysate of imipenem, a carbapenem with a good leaving group, can be used in screening for broad-spectrum inhibitors of MβLs.

scholarly journals The stereochemical course of reactions catalysed by the cellobiohydrolases produced by Talaromyces emersonii

1992 ◽  
Vol 283 (1) ◽  
pp. 31-34 ◽  
Author(s):  
M M Brooks ◽  
M G Tuohy ◽  
A V Savage ◽  
M Claeyssens ◽  
M P Coughlan
Keyword(s):  
Degradation Product ◽  
Proteolytic Degradation ◽  
Substrate Specificities ◽  
Talaromyces Emersonii ◽  
Anomeric Configuration ◽  
Culture Filtrates ◽  
Apparent Homogeneity ◽  
Displacement Reactions ◽  
Hydrolysis Of

Three forms of exocellobiohydrolase (EC 3.2.1.91), CBH IA, CBH IB and CBH II, were isolated to apparent homogeneity from culture filtrates of the aerobic fungus Talaromyces emersonii. CBH IA and CBH II appear to be native forms of these enzymes, while CBH IB may represent a proteolytic degradation product of the CBH IA enzyme. The hydrolysis of beta-cellobiosyl fluoride by each form was monitored by 1H-n.m.r. spectroscopy. The reactions catalysed by CBH IA and CBH IB proceed with retention of the anomeric configuration, whereas that catalysed by CBH II is one of inversion. Thus one may deduce that CBH IA (or CBH IB) and CBH II operate double and single displacement reactions respectively during catalysis of substrate. On the basis of these findings and the observed substrate specificities of the various forms, one may conclude that CBH IA (and CBH IB) is a family C enzyme, while CBH II belongs to family B [Henrissat, Claeyssens, Tomme, Lemesle & Mornon (1989) Gene 81, 83-95].

New Reactive Coenzyme Analogues for Affinity Labeling of NAD+ and NADP+ Dependent Dehydrogenases

1995 ◽  
Vol 50 (7-8) ◽  
pp. 476-486
Author(s):  
Reinhard Jeck ◽  
Michael Scholze ◽  
Anja Tischlich ◽  
Christoph Woenckhaus ◽  
Jürgen Zimmermann
Keyword(s):  
Adenosine Diphosphate ◽  
Competitive Inhibitor ◽  
Hydrogen Donor ◽  
Reduced Form ◽  
Irreversible Inhibitor ◽  
Hydrocarbon Chains ◽  
Phosphoric Acid Ester ◽  
Acetyl Group ◽  
Hydrolysis Of ◽  
Phosphate Groups

Abstract Reactive coenzyme analogues ω-(3-diazoniumpyridinium)alkyl adenosine diphosphate were prepared by reaction of ω-(3-aminopyridinium)alkyl adenosine diphosphate with nit­rous acid. In these compounds the nicotinamide ribose is substituted by hydrocarbon chains of varied lengths (n-ethyl to n-pentyl). The diazonium compounds are very unstable and decompose rapidly at room temperature. They show a better stability at 0 °C. L actate and alcohol dehydrogenase do not react with any of the analogues. Glyceraldehyde-3-phosphate dehydrogenase reacts rapidly with the diazonium pentyl compound. Decreasing the length of the alkyl chain significantly decreases the inactivation velocity. 3α,20β-Hydroxysteroid dehydrogenase reacts at 0 °C with the ethyl homologue and slowly with the propyl compound. The butyl-and pentyl analogues do not inactivate at 0 °C. Tests with 14C -labeled 2-(3-diazoniumpyridinium)ethyl adenosine diphosphate show that complete loss of enzyme activity results after incorporation of 2 moles of inactivator into 1 mole of tetrameric enzyme. 4-(3-Acetylpyridinium)butyl 2 ′-phospho-adenosine diphosphate, a structural analogue of NADP +, was prepared by condensation of adenosine-2,3-cyclophospho-5′-phosphomorpholidate with (3-acetylpyridinium)butyl phosphate, followed by hydrolysis of the cyclic phosphoric acid ester with 2 ′:3′-cyclonucleotide-3′-phosphodiesterase. Because of the redox potential (-315 mV) and the distance between the pyridinium and phosphate groups, this analogue is a hydrogen acceptor and its reduced form a hydrogen donor in tests with alcohol dehyd roge­nase from Thermoanaerobium brockii. The reduced form of the coenzyme analogue also is a hydrogen donor with glutathione reductase. With other NADP +-dependent dehydrogenases the com pound has been show n to be a competitive inhibitor against the natural coenzyme. The acetyl group reacts with bromine to form the bromoacetyl group. This reactive bromoacetyl analogue is a specific active-site directed irreversible inhibitor of isocitrate dehydrogenase.

scholarly journals Potential Anti-Acetylcholinesterase Activity of Cassia timorensis DC.

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4545
Author(s):  
Nurul Amira Nurul Azman ◽  
Maram B. Alhawarri ◽  
Mira Syahfriena Amir Rawa ◽  
Roza Dianita ◽  
Amirah Mohd Gazzali ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Acetylcholinesterase Activity ◽  
The Other ◽  
Hydroxyl Group ◽  
Anionic Site ◽  
Methanol Extracts ◽  
Plant Parts ◽  
Ache Inhibitory Activity ◽  
First Time ◽  
Hydrolysis Of

Seventeen methanol extracts from different plant parts of five different Cassia species, including C. timorensis, C. grandis, C. fistula, C. spectabilis, and C. alata were screened against acetylcholinesterase (AChE). C. timorensis extracts were found to exhibit the highest inhibition towards AChE whereby the leaf, stem, and flower methanol extracts showed 94–97% inhibition. As far as we are aware, C. timorensis is one of the least explored Cassia spp. for bioactivity. Further fractionation led to the identification of six compounds, isolated for the first time from C. timorensis: 3-methoxyquercetin (1), benzenepropanoic acid (2), 9,12,15-octadecatrienoic acid (3), β-sitosterol (4), stigmasterol (5), and 1-octadecanol (6). Compound 1 showed moderate inhibition towards AChE (IC50: 83.71 μM), while the other compounds exhibited poor to slightly moderate AChE inhibitory activity. Molecular docking revealed that the methoxy substitution of 1 formed a hydrogen bond with TYR121 at the peripheral anionic site (PAS) and the hydroxyl group at C5 formed a covalent hydrogen bond with ASP72. Additionally, the OH group at the C3′ position formed an interaction with the protein at the acyl pocket (PHE288). This possibly explains the activity of 1 in blocking the entry of acetylcholine (ACh, the neurotransmitter), thus impeding the hydrolysis of ACh.

THE HYDROLYSIS OF p-ACETOXYPHENYLETHYLAMINES BY INSECT CHOLINESTERASE

1958 ◽  
Vol 36 (1) ◽  
pp. 145-152
Author(s):  
L. S. Wolfe ◽  
G. D. Thorn
Keyword(s):  
Human Serum ◽  
Carbonyl Oxygen ◽  
Rectus Abdominis ◽  
Hydrolysis Rate ◽  
Rectus Abdominis Muscle ◽  
Oxygen Separation ◽  
Bovine Erythrocyte ◽  
Acetyl Group ◽  
Hydrolysis Of ◽  
Derivatives Of

The synthesis of the acetyl derivatives of tyramine and hordenine is described. The O-monoacetyl derivatives are hydrolyzed at significant rates by bovine erythrocyte cholinesterase, human serum, and fly head cholinesterase despite a nitrogen to carbonyl oxygen separation approximately twice that of acetylcholine. The pS-activity relationships, when O-acetyltyramine and acetylcholine were substrates for fly head cholinesterase, were similar, but the hydrolysis rate of O-acetyltyramine was much higher than that of acetylcholine. N-Acetylation of the O-acetyl compounds reduced the hydrolysis rate. None of the cholinesterases removed the acetyl group attached to nitrogen. The pI-activity relationships with the inhibitors Nu-683, Nu-1250, TEPP, and eserine showed that the hydrolysis of p-acetoxyphenylethylamine derivatives and acetylcholine by fly head preparations was accomplished by the same cholinesterase and not by aromatic or aliesterases. O-Acetylation of hordenine methiodide destroyed its nicotinelike action on frog rectus abdominis muscle.

ESTIMATION OF CORTICOSTEROIDS BY THE REDUCTION OF FERRICYANIDE

1959 ◽  
Vol 37 (1) ◽  
pp. 391-398 ◽  
Author(s):  
N. R. Stephenson
Keyword(s):  
Prussian Blue ◽  
Blood Sugar ◽  
Alkaline Medium ◽  
Alkaline Solution ◽  
Reducing Power ◽  
Hydroxyl Group ◽  
Side Chain ◽  
Inhibiting Effect ◽  
Reducing Activity ◽  
Hydrolysis Of

A procedure based on a modification of Folin's micromethod for blood sugar (1, 2) was used to investigate the reducing activity of various corticosteroids. The ferrocyanide produced as a result of the reduction of ferricyanide in alkaline solution was measured photometrically as Prussian blue. With a filter transmitting light at 620 mμ, the relation between the absorbance of the chromogen and the amount of the reducing steroid obeyed Beer's law over the range from 0.005 to 0.050 mg. The oxygen function at C-3 accounted for most of the reducing power of the non-alpha ketolic steroids studied. An oxygen function at C-11 did not affect significantly the reduction of ferricyanide by 17-desoxycorticosteroids. Although the presence of a hydroxyl at C-17 depressed the reducing activity of the alpha-ketol side chain, a fluorine at C-9 and an hydroxyl at C-11 appeared to overcome this inhibiting effect. Evidence was obtained to suggest that a C-16 hydroxyl group was able to increase the reducing action of the alpha-ketolic side chain. Esterification of the C-21 hydroxyl influenced the reduction of ferricyanide only when interference with hydrolysis of the ester in the alkaline medium was experienced.

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