Novel aminocyclitol antibiotics derived from natural carbohydrates.
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Amino Sugars↗
Biomedical subjects
G Batta
Publications and source records attributed to G Batta.
Synthesis of new pseudodisaccharide aminoglycoside antibiotics from carbohydrates.
Novel pseudodisaccharide-type aminocyclitol antibiotic models, built up from D-arabinose, D-ribose, D-glucosamine, L-ristosamine and L-acosamine have been synthesized by the glycosylation of suitably protected (azido)deoxyinosose aglycones derived by the Ferrier carbocyclic ring transformation of carbohydrate precursors. An alternative approach to related pseudodisaccharides, based on the Ferrier carbocyclization of reducing disaccharides, has also been elaborated. This latter method extends the scope of the Ferrier reaction, by demonstrating that acid-labile 2-deoxydisaccharides can also be readily transformed into the corresponding pseudodisaccharides under the slightly acidic conditions of this ring-transformation.
Aminoglycosides↗
An NMR study of eremomycin and its derivatives. Full 1H and 13C assignment, motional behavior, dimerization and complexation with Ac-D-Ala-D-Ala.
Complete 1H and 13C NMR assignments are presented for eremomycin (1) and some of its desglycosylated derivatives 2, 3 and compared to the structurally closely related glycopeptide vancomycin. Primary structure and stereochemistry of eremomycin is corroborated by the present high field total correlation spectroscopy, NOESY and heteronuclear multiple-bond correlation NMR methods. A rough motional characterization of the title compound is attempted by 13C-T1 and 13C-[1H] NOE measurements. Dimerization of eremomycin is observed both in DMSO-d6-CCl4 and D2O solutions. Complexation with cell wall analogue dipeptide Ac-D-Ala-D-Ala is also demonstrated.
Anti-Bacterial Agents↗
Proof of the structure of ristotetraose: synthesis of propyl alpha-ristotetraoside.
A definitive synthesis of the propyl glycoside (1) of ristotetraose, the heterotetrasaccharide component of the antibiotic ristomycin A (ristocetin A) is described.
Carbohydrate Conformation↗
Intramolecular H-bonds and thioamide rotational isomerism in thiopeptides.
Mono- and dithionated N-acyl amino acid and dipeptide N'-methylamides were synthesized using Lawesson's reagent and S-thioacetyl thioglycolic acid. The conformation of the thionated models was characterized by IR, 13C, and 1H NMR spectroscopy, including NOE experiments. The formation of -C = S...H-N-C = X (X = O or S) intramolecular H-bonds of the type 2----2, 1----3 and 1----4 was evidenced by the characteristic shifts of the IR stretching frequencies of the NH group. Act-Pro-NHCH3(4) and Act-Prot-NHCH3(5) were found to be present as mixtures of rotational isomers about the CS-N bond. 13C chemical shifts of the gamma- and beta-carbons of the proline ring elucidated the conformation (Z or E) of the tertiary thioamide group. Our results suggest that the conformation of thiopeptides is determined by two factors: 1) the H-bond donating and accepting ability of the thioamide group and 2) the repulsion between the thiocarbonyl sulfur atom and the side chain groups of the neighbouring amino acid residues.
Dipeptides↗
13C NMR study of actinoidins: carbohydrate moieties and their glycosidic linkages.
The configuration of the glycosidic linkages and the conformation of the carbohydrate moieties in the molecules of the glycopeptide-type antibiotics actinoidins A and B (1a, 1b) have been determined by means of two-dimensional 13C/1H correlation NMR technique and with the application of model compounds 2-4.
Carbohydrate Conformation↗
[Correction of current values of the metabolic profile in calves with hemoconcentration].
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Animals↗
[Hemoconcentration in calves and its relation to the hematologic, protein, mineral and electrolyte profile].
The dynamics of hematological, protein, mineral and electrolytic profile was examined clinically in nine calves when the hemoconcentration was induced experimentally. The hemoconcentration occurred after diarrhea caused by the per os application of 12 g saccharose per one kg of live weight. The hemoconcentration culminated six hours after application. The calves where the hemoconcentration did not exceed the critical value were included in the first group, and the calves with the extreme hemoconcentration values in the other group. In the first group (with the increasing hemoconcentration degree), a statistically significant increase was found in the values of hematocrit, erythrocytes, hemoglobin, total protein in blood serum and total immunoglobins and a statistically insignificant increase in the levels of leucocytes, inorganic phosphorus, serum calcium and sodium. Serum potassium and magnesium showed the inverse dynamics, i. e. the decrease. In the second group (with the extreme hemoconcentration), hyperkalemia and slight hypermagnesemia were identified, while the other parameters showed deviations similar to those observed in the first group. After the rehydration of animals by a preparation without any influence on the studied parameters, the hemoconcentration and the parameters under study stabilized, while in the second group the hemoconcentration was increasing even during the rehydration and the levels of serum potassium and magnesium showed different tendencies. As follows from the results, in the calves suffering from scours accompanied by hemoconcentration the correction of the parameters of metabolic profile is necessary.
Animals↗
[Hemoconcentration in calves in relation to actual and corrected values of metabolic profile parameters].
Frequent pathogenetic condition of hemoconcentration in calves results in apparent increase in the parameters of metabolic profile above the standard level. These values, however, do not conform to the actual state and often lead to unsubstantiated diagnostic conclusions with pathological deviations. On the basis of experimental study on the dynamics of some parameters of hematological, protein, mineral and electrolytic profile in the calves with experimental hemoconcentration, a correction table and diagram for the calculation of corrected values for some parameters of metabolic profile were elaborated. At hematocrit value increased above the physiologic limit (0.45--0.60) the correction values of parameters in percent are subtracted from the actual value. The correction table was used to correct actual values of those parameters of metabolic profile which during the experimental hemoconcentration were found to have direct relations to the dynamics (Er, Hb, Le, CB, Ig, serum Ca, P and Na). The correction of serum potassium and of some enzymes (AST, ALT, gMT) is not indicated because no relations were determined. Whereas the actual values of the studied parameters reached their maxima (statistically significant differences in Er, Hb, CB, Ig levels) at the culmination of hemoconcentration (6th hour--1st sampling), the differences between the corrected values and initial values were in all parameters insignificant. The correction of actual values of parameters by means of the diagram or table is simple, expeditious and reliable.
Animals↗
[Gamma-glutamyltransferase activity in the blood of calves].
The activity of gMT in the blood serum of calves was studied in relation to the age, concentration of total immunoglobulins (Ig) and protein (TP) and to the volume of colostrum taken in by the calves during the first post-partum sucking. Before sucking the serum activity of gMT in newborn calves is low; later it assumes an ascending tendency, the maximum activity being recorded in the 24th hour from birth. A continuous decrease follows in the subsequent postnatal period and the physiological values (of adult cattle) are obtained in the sixth to seventh weeks of age. A marked correlation was found between the values of Ig and gMT (r = 0.9988), and TP and gMT (r = 0.9911), in newborn calves at the age of 48 hours. A highly significant difference was also found in the activity of gMT (P less than 0.01) in calves with different post-partum Ig concentrations. Attention is drawn to the significant difference in the serum activity of gMT (P less than 0.05), Ig (P less than 0.01) and TP (P less than 0.05) in calves given different amounts of the first colostrum. The results of the study can be used for the evaluation of metabolic tests in calves during the early postnatal period.
Animals↗