scholarly journals THE BIOCHEMISTRY OF THE USTILAGINALES: III. THE DEGRADATION PRODUCTS AND PROOF OF THE CHEMICAL HETEROGENEITY OF USTILAGIC ACID

1951 ◽  
Vol 29 (5) ◽  
pp. 415-425 ◽  
Author(s):  
R. U. Lemieux
Keyword(s):  
Acetic Acid ◽  
Methyl Ester ◽  
Caprylic Acid ◽  
Degradation Products ◽  
Caproic Acid ◽  
Specific Rotation ◽  
Chemical Heterogeneity ◽  
Hydroxy Acids ◽  
Hydrolysis Of ◽  
Derivatives Of

The D-glucolipid designated as ustilagic acid was shown to be a mixture of partially acylated derivatives of a di-D-glucosyl-dihydroxyhexadecanoic acid. The dihydroxyhexadecanoic acid was named "ustilic acid" and its di-D-glucosyl derivative was termed "glucoustilic acid". Alkaline hydrolysis of ustilagic acid yielded glucoustilic acid, acetic acid, dextro-β-hydroxy-n-caproic acid, dextro-β-hydroxy-n-caprylic acid and a small amount of n-caproic acid. The β-hydroxy-acids were characterized as dextro-β-hydroxy-n-caprohydrazide, m.p. 131–132°C., [α]D + 15.9° (water), and dextro-β-hydroxy-n-caprylhydrazide, m.p. 127–128°C., [α]D + 12° (water). Ustilic acid, m.p. 114–115°C., [α]D − 6.3° (methanol), yielded a methyl ester, m.p. 80−81.8°C, [α]D − 0.2 (chloroform). The methyl ustilate formed a di-phenylurethane derivative, m.p. 76–77°C. The infrared spectra of crystalline and amorphous samples of ustilagic acid are given. The specific rotation of glucoustilic acid, [α]D − 11° (methanol) was that expected of β-D-glucosides and the infrared spectrum of this substance showed a marked resemblance to that of methyl-β-D-glucopyranoside.

Preparation and Conformational Analysis of 1,2-Seco Derivatives of 19β,28-Epoxy-18α-oleanane

2000 ◽  
Vol 65 (8) ◽  
pp. 1339-1356 ◽  
Author(s):  
Jan Sejbal ◽  
Martina Homolová ◽  
Iva Tišlerová ◽  
Václav Křeček
Keyword(s):  
Acetic Acid ◽  
Molecular Modelling ◽  
Free Acid ◽  
Single Bond ◽  
Reaction Type ◽  
Chromium Vi ◽  
Cannizzaro Reaction ◽  
Nmr Methods ◽  
Hydrolysis Of ◽  
Derivatives Of

Oxidation of 19β,28-epoxy-18α-oleanan-3-one (1) with chromium(VI) oxide in acetic acid leads to the formation of the 1β,3β;19β,28-diepoxy-3-hydroxy-1,2-seco-18α-oleanano- 2,1α-lactone (2). Its structure follows from spectral data, molecular modelling. Lactone 2 was converted to its acetate 3, methyl 19β,28-epoxy-1,3-dioxo-1,2-seco-18α-oleanan-2-oate (4) and to the stereoisomers at C(3) of methyl 1,3;19β,28-diepoxy-1-oxo-1,2-seco-18α-oleanan-2-oate (6 and 7) and dimethyl 19β,28-epoxy-3-hydroxy-1,2-seco-18α-oleanan-1,2-dioate (8 and 9). Lactone 2 reacts slowly with diazomethane which is indicative for its equilibrium with a small amount of free acid. Alkaline hydrolysis of compound 2 leads to compounds 8 and 9; the reaction involves hydride transfer of a Cannizzaro reaction type. A high rotational barriers were found in compounds 8 and 9. A combination of NMR methods and molecular modelling revealed that most sterically hindered bond in both compounds is the C(1)-C(10) single bond.

scholarly journals Preparation of Sterically Demanding 2,2-Disubstituted-2-Hydroxy Acids by Enzymatic Hydrolysis

Catalysts ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 113 ◽  
Author(s):  
Andrea Pinto ◽  
Immacolata Serra ◽  
Diego Romano ◽  
Martina Contente ◽  
Francesco Molinari ◽  
...  
Keyword(s):  
Enzymatic Hydrolysis ◽  
Phenylacetic Acid ◽  
General Structure ◽  
Hydroxy Acids ◽  
Pig Liver Esterase ◽  
Liver Esterase ◽  
Sterically Demanding ◽  
Optically Pure ◽  
Hydrolysis Of ◽  
Derivatives Of

Preparation of optically-pure derivatives of 2-hydroxy-2-(3-hydroxyphenyl)-2-phenylacetic acid of general structure 2 was accomplished by enzymatic hydrolysis of the correspondent esters. A screening with commercial hydrolases using the methyl ester of 2-hydroxy-2-(3-hydroxyphenyl)-2-phenylacetic acid (1a) showed that crude pig liver esterase (PLE) was the only preparation with catalytic activity. Low enantioselectivity was observed with substrates 1a–d, whereas PLE-catalysed hydrolysis of 1e proceeded with good enantioselectivity (E = 28), after optimization. Enhancement of the enantioselectivity was obtained by chemical re-esterification of enantiomerically enriched 2e, followed by sequential enzymatic hydrolysis with PLE. The preparation of optically-pure (S)-2e was validated on multi-milligram scale.

Behavior of Amiben and Dinoben Derivatives in Arkansas Soils

Weed Science ◽  
1970 ◽  
Vol 18 (1) ◽  
pp. 10-15 ◽  
Author(s):  
R. E. Talbert ◽  
R. L. Runyan ◽  
H. R. Baker
Keyword(s):  
Methyl Ester ◽  
Organic Matter Content ◽  
Matter Content ◽  
Digitaria Sanguinalis ◽  
Culture Studies ◽  
Aluminum Salts ◽  
Dry Soil ◽  
Rapid Hydrolysis ◽  
Hydrolysis Of ◽  
Derivatives Of

The influence of six Arkansas soils on the leaching characteristics of derivatives of 3-amino-2,5-dichlorobenzoic acid (amiben) and 3-nitro-2,5-dichlorobenzoic acid (hereinafter referred to as dinoben) in slotted soil columns was determined using large crabgrass [Digitaria sanguinalis (L.) Scop.] bioassay. The ammonium and aluminum salts of amiben and the sodium salt of dinoben were easily leached and leaching was not noticeably affected by soil type. The ammonium salt of amiben was not adsorbed, while the methyl ester of amiben was adsorbed by these soils. Adsorption was related to the clay and organic matter content of the soil. Methyl and butoxyethyl ester derivatives of amiben and dinoben resisted leaching in these soils and the amide of amiben was intermediate in leaching. The adsorption and leaching behavior of the ester derivatives of these compounds were complicated by their rapid hydrolysis in these soils. The hydrolyzed product behaved identically to the salt derivatives of the compounds in leaching, adsorption, and chromatographic properties. Hydrolysis of the methyl ester was inhibited by soil sterilization, dry soil, and temperatures below 20 C. In non-sterile, warm, moist soil, the half-life of the methyl ester of amiben was 28 hr. Four species of Bacillus were capable of hydrolyzing the methyl ester of amiben in pure culture studies.

scholarly journals The therapeutic action of some bismuthyl derivatives of organic hydroxy-acids

1927 ◽  
Vol 102 (713) ◽  
pp. 1-9 ◽  
Keyword(s):  
Acetic Acid ◽  
Citric Acid ◽  
Marked Effect ◽  
Peripheral Circulation ◽  
Amorphous Solids ◽  
Therapeutic Action ◽  
Hydroxy Acids ◽  
Infected Blood ◽  
Mineral Acids ◽  
Derivatives Of

The chemotherapeutic action of compounds of bismuth in spirochætal infections was observed by Robert and Sauton. These workers found that sodium bismuthyl tartrate had a marked effect in preventing and curing infection with Spirochæta gallinarum (Fowl Spirillosis). Since then the action of compounds of bismuth has been extensively investigated in spirochætal infections (see Levaditi). The present work concerns the bismuth derivatives of organic hydroxy-acids. All the compounds investigated are white amorphous solids, of which only the derivatives of the monobasic sugar acids are at all soluble in water. They are stable to acetic acid, but are instantly decomposed by dilute mineral acids; and; with the exception of the citric acid and ester com­pounds, are soluble in alkali. The therapeutic action of these compounds was tested in the case of mice infected with Sp. laverani (Breinl and Kinghorn; Sp. muris of Wenyon). Infections with the strain used, which was non-pathogenic for mice, had the following characteristics:—As a rule, five or six days after subcutaneous in­ oculation with a suspension in saline of infected blood, the organisms were found in the peripheral circulation in small numbers. Thereafter they usually became more numerous and persisted for long periods. Their abundance in the blood appeared to vary from time to time and after some months they might become very scanty. The value of this infection as a test for chemotherapeutic pro­perties lies in the fact that it is susceptible to agents such as salvarsan, which are effective in the treatment of infections with Tr. pallidum .

scholarly journals Kinetics and mechanism of catalysis by proteolytic enzymes. A comparison of the kinetics of hydrolysis of synthetic substrates by bovine α- and β-trypsin

1974 ◽  
Vol 141 (2) ◽  
pp. 545-554 ◽  
Author(s):  
D. V. Roberts ◽  
D. T. Elmore
Keyword(s):  
Methyl Ester ◽  
Proteolytic Enzymes ◽  
Catalytic Efficiency ◽  
Kinetics And Mechanism ◽  
Molecular Flexibility ◽  
Kinetics Of Hydrolysis ◽  
Mechanism Of Catalysis ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Several esters of the α-N-toluene-p-sulphonyl and α-N-benzoyl derivatives of S-(3-aminopropyl)-l-cysteine and the methyl ester of S-(4-aminobutyl)-N-toluene-p-sulphonyl-l-cysteine were synthesized. The kinetics of hydrolysis of these and esters of the α-N-toluene-p-sulphonyl and α-N-benzoyl derivatives of l-arginine, l-lysine, S-(2-aminoethyl)-l-cysteine and esters of γ-guanidino-l-α-toluene-p-sulphonamidobutyric acid and α-N-toluene-p-sulphonyl-l-homoarginine by α- and β-trypsin were compared. On the basis of values of the specificity constants (kcat./Km), the two enzymes display similar catalytic efficiency towards some substrates. In other cases α-trypsin is less efficient than β-trypsin. It is possible that α-trypsin possesses greater molecular flexibility than β-trypsin.

The α-Chymotrypsin-catalyzed Hydrolysis of α-N and O-Alkyl Derivatives of α-N-Acetyl-L-tyrosine Methyl Ester*

Biochemistry ◽  
1963 ◽  
Vol 2 (5) ◽  
pp. 942-946 ◽  
Author(s):  
Roger L. Peterson ◽  
Konrad W. Hubele ◽  
Carl Niemann
Keyword(s):  
Methyl Ester ◽  
Alkyl Derivatives ◽  
Hydrolysis Of ◽  
Derivatives Of

Hydrolysis of O-Acetylsalicylic Acid (Aspirin) in Relation to the Aspirin-Bromate-Acid Oscillating System

2006 ◽  
Vol 71 (10) ◽  
pp. 1445-1452 ◽  
Author(s):  
Ľubica Adamčíková ◽  
Daniel Mišicák ◽  
Peter Ševčík
Keyword(s):  
Acetic Acid ◽  
Salicylic Acid ◽  
Acetylsalicylic Acid ◽  
Induction Period ◽  
Rate Constant ◽  
Degradation Products ◽  
Oscillatory Behavior ◽  
Active Substrate ◽  
Hydrolysis Of

The uncatalyzed BrO3--O-acetylsalicylic acid (aspirin) reaction in aqueous H2SO4 exhibits oscillatory behavior. The induction period observed before the onset of oscillations depends on the extent of hydrolysis of aspirin. The rate constant of hydrolysis of aspirin was determined indirectly from the value of induction period. When aspirin undergoes hydrolysis, the degradation products are salicylic acid and acetic acid. Salicylic acid may play a role of "active" substrate responsible for the oscillations. Aspirin (Bayer) generates also oscillations with bromate.

Accumulation of Macromolecular Particles in the Reticuloendothelial System (RES) Mediated by Platelet Aggregation and Disaggregation

1969 ◽  
Vol 22 (03) ◽  
pp. 496-507 ◽  
Author(s):  
W.G van Aken ◽  
J Vreeken
Keyword(s):  
Platelet Aggregation ◽  
Degradation Products ◽  
Reticuloendothelial System ◽  
Caproic Acid ◽  
Carbon Particles ◽  
Carbon Clearance ◽  
Aggregation And Disaggregation ◽  
Platelet Aggregates

SummaryCarbon particles cause platelet aggregation in vitro and in vivo. Prior studies established that substances which modify thrombocyte aggregation also influence the rate at which carbon is cleared from the blood.This study was performed in order to elucidate the mechanism by which the carbon-platelet aggregates specifically accumulate in the RES.Activation of fibrinolysis by urokinase or streptokinase reduced the carbon clearance rate, probably due to generated fibrinogen degradation products (FDP). Isolated FDP decreased the carbon clearance and caused disaggregation of platelets and particles in vitro. Inhibition of fibrinolysis by epsilon-amino-caproic acid (EACA), initially accelerated the disappearance of carbon and caused particle accumulation outside the RES, predominantly in the lungs. It is supposed that platelet aggregation and locally activated fibrinolysis act together in the clearance of particles. In the normal situation the RES with its well known low fibrinolytic activity, becomes the receptor of the particles.

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