Degradation Of Penicillin Research Articles

Effect of Organic Solutions on the Stability and Extraction Equilibrium of Penicillin G

The effects of organic solutions on the stability and extraction equilibrium of penicillin G were investigated. N-Butyl acetate, methyl isobutyl ketone, 2-ethyl hexanol, kerosene, and n-heptane were used for physical extraction; di-N-octylamine, tri-N-octylamine, N235 (a mixture of tertiary amines), tributyl phosphate, and di-(2-ethylhexyl)phosphoric acid were used as the extractants, with N-butyl acetate, kerosene, and n-heptane as diluents for reactive extraction. The degradation efficiency of penicillin G increases with increasing temperature. The stability of penicillin G was better in the presence of an amine-based extractant, while it was worse in the presence of a phosphorus acid extractant. The effect of neutral extractant on the stability of penicillin G was mainly dependent on the temperature. The degradation of penicillin G in alkali solution was governed by pH. The efficiency of physical extraction of penicillin G increased with decreasing pH in the aqueous solution. The efficiency of reactive extraction with an amine-based extractant was highest under the range studied. The extractant of phosphorus acid was better than neutral phosphorus extractant for the extraction of penicillin G. The distribution coefficient decreases with increasing pH, temperature, and initial penicillin G concentration in the aqueous solution under the studied conditions. The mechanism of degradation and extraction was also discussed.

Preparation and photocatalytic activity of nanoglued Sn-doped TiO 2

In this paper, Sn-doped TiO 2 photocatalyst was prepared and immobilized on a glass substrate using an about-to-gel SiO 2 sol as a nanoglue. The characterization of the Sn-doped TiO 2 by XRD showed that 5% Sn content is formed by anatase and rutile crystallites. Characterization of the nanoglued photocatalyst by the BET measurement, TEM, and SEM showed that the photocatalyst was a nanoporous material with a high-surface area. The Sn-doped TiO 2 was uniformly dispersed within the three-dimensional network of the silica in the form of nanoparticles. The nanoglued photocatalyst showed high photocatalytic activity during the degradation of penicillin under UV light. The effect of different Sn content on the amount of hydroxyl radical was discussed by using salicylic acid as probe molecules. The results show that an appropriate amount of Sn dopant can greatly increase the amount of hydroxyl radicals generated by TiO 2 nanoparticles, which are responsible for the obvious increase of photocatalytic activity.

Cold-temperature stability of five β-lactam antibiotics in bovine milk and milk extracts prepared for liquid chromatography–electrospray ionization tandem mass spectrometry analysis

The stability of five major β-lactam antibiotics (amoxicillin, ampicillin, cloxacillin, oxacillin, and penicillin G) in fortified milk and in milk extracts prepared for LC-ESIMS/MS analysis was studied at varying cold temperatures (4, −20, and −76 °C). Storage of milk samples at 4 °C resulted in measurable losses of all β-lactams after 6 days (>50% in most cases). Slow degradation of penicillin G, cloxacillin, and oxacillin was observed in milk stored at −20 °C, but no losses were recorded at −76 °C over 4 weeks. All antibiotics showed good stability at all temperature tested in milk extracts prepared for LC-ESIMS/MS analysis. The results of this study emphasize adherence to adequate sample handling and storage protocols as to reflect residue levels at the time of sample submission.

Influence of magnesium glutamate on stability of penicillin G aqueous solution

Differential scanning microcalorimetry (DSC) has been used to determine the influence of magnesium glutamate on the stability of penicillin G in aqueous solution. The degradation of penicillin is accompanied by an evolution of heat and has been observed as an irreversible, scan rate dependent, broad exothermic transition. The increase of the transition temperature T m and enthalpy change Δ H with increasing magnesium glutamate concentration indicates the increase of penicillin G stability. The kinetic parameters describing the penicillin decomposition process, obtained for a reaction following a first-order course, suggest maximum penicillin G stability if about two molecules of salt per one penicillin molecule are present in solution.

β-Lactam degradation catalysed by Cd 2+ ion in methanol

Kinetic schemes are established for degradation catalysed by Cd 2+ ions in methanolic medium for penicillin G, penicillin V and cephalothin, a cephalosporin. Methanolysis of penicillin V and cephalothin occurs with the formation of a single substrate-metal ion intermediate complex, SM, while degradation of penicillin G occurs with the initial formation of two complexes with different stoichiometry, SM and S 2M. In each case, degradation is of first order with respect to SM with rate constant values equal to 0.079 min −1, 0.120 min −1 and 0.166 min −1at 20, 25 and 30°C, respectively, for penicillin G; 0.061 min −1 at 20°C for penicillin V; and 2.0×10 −3 min −1 at 20°C for cephalothin. Activation energy for the decomposition process of the SM intermediate for penicillin G was calculated to be about 5.5×10 4 J/mol. Equilibrium constant values between SM compound and S 2M at 20°C (77.1 l/mol), 25°C (45.3 l/mol) and at 30°C (25.7 l/mol) were also calculated as well as the normal enthalpy of this equilibrium. With respect to the reaction products there is evidence that Cd 2+ becomes part of their structure, forming complexes between Cd 2+ and the product resulting from antibiotic methanolysis (L). Some characteristics of these complexes are discussed.

Autolysis in Batch Cultures of Penicillium Chrysogenum at Varying Agitation Rates

The process of autolysis in batch cultures of an industrial strain of Penicillium chrysogenum was investigated at a range of stirrer speeds. Autolysis in the cultures was monitored by conventional analysis (biomass decline, NH 4 + release), direct measurement of autolysing regions (image analysis), and enzyme activity assays (proteases and β-glucanases). Image analysis measurements provided a sensitive indicator of the onset and progress of autolysis in the culture. Autolysis could be brought about by C or n limitation. Culture history could have a marked effect on the process. Autolysis resulted in degradation of penicillin V and problems with broth filterability. It was closely associated with increased intracellular proteolytic and β-1-3-glucanolytic activities. Although stirrer speed affected both growth and penicillin V production, final mean main hyphal lengths were similar in autolysing cultures. This indicated a possible role of an intrinsic characteristic in fragmentation.

Determination of Penicillin G in Beef and Pork Tissues Using an Automated LC Cleanup

A procedure previously described for determination of β-lactam antibiotics in milk was modified for use with tissues. Tissues were extracted directly with acetonitrile (procedure I) to avoid degradation of penicillin G in water homogenates. Recovery of penicillin G in acetonitrile extracts of tissues was improved by addition of tetraethylammonium chloride and, in some cases, pH adjustment. The acetonitrile extracts were concentrated by evaporation and filtered. For cleanup, an automated high-performance liquid chromatography (HPLC) fractionation was used. The fraction corresponding to penicillin G was tested by a rapid screening test and, if positive, was analyzed by HPLC. For analysis, an Inertsil ODS-2 column was used with a mobile phase of 0.0067 M KH2PO4, 0.0033 M H3PO4−acetonitrile (68 + 32) with UV detection at 215 nm. For confirmation by treatment with β-lactamase, tissues were homogenized in water. An aliquot of the water homogenate was treated with β-lactamase prior to extraction with acetonitril...

Measurement of autolysis in submerged batch cultures ofPenicillium chrysogenum

The process of cellular autolysis was studied in an industrial strain of Penicillium chrysogenum by a range of methods, including assessment of biomass decline, NH+4 release, changes in culture apparent viscosity, and by means of a quantitative assessment of changes in micromorphology using a computerized image analysis system. The pattern of total intracellular proteolytic and beta-1, 3-glucanolytic activity in the culture was also examined. The overall aim was to identify a suitable method, or methods, for examining the extent of autolysis in fungal cultures. Autolysis was studied in submerged batch processes, where DOT was maintained above 40% saturation (non-O2-limited), and, under O2-limited conditions. Both N and O2 limitation promoted extensive culture autolysis. Image analysis techniques were perhaps the most sensitive method of assessing the progress of autolysis in the culture. Autolytic regions within some hyphae were apparent even during growth phase, but became much more widespread as the process proceeded. The early stages of autolysis involved continued energy source consumption, increased carbon dioxide evolution rate, degradation of penicillin, and decreased broth filterability. Later stages involved widespread mycelial fragmentation, with some regrowth (cryptic growth) occurring in non-O2-limited cultures. Intracellular proteolytic activity showed two peaks, one during the growth phase, and the other during autolysis. Autolysis was also associated with a distinct peak in beta-1,3-glucanolytic activity, indicating that degradation of cell wall matrix polymers may be occurring during autolysis in this strain of P. chrysogenum.

The stability of penicillin G during recovery by electrically enhanced extraction

The effect of high-voltage electric fields on the degradation of penicillin G has been studied in the context of the electrostatically enhanced solvent extraction of penicillin from whole broths. Eight parameters (voltage, penicillin G concentration, pH, presence of whole broth material, electrical polarity, solvent exposure, joule heating and residence time) were studied.

Determination of penicillin complexation sites in the presence of Zn(II) ions by AM1 and PM 3 methods

In this study we have carried out semiempirical AM1 and PM3 calculations on a simplified penicillin molecule (i.e. methylpenicillin) in the presence of the Zn(II) ion to assess the probable complex structures and to gain additional information on the mechanism of the metal-ion promoted hydrolysis of penicillins. Theoretical investigations based on calculated heats of formation Δ H f predict formation of two complexes of comparable thermochemical stability in aqueous solutions of methylpenicillin in the presence of Zn(II): by the COO − group alone and by the COO − group and β-lactam ring nitrogen atom. The former structure, with four watermolecules, is slightly favoured Δ H f lower by 6.5 kcal mol −1 (AM1)and 10.7kcal mol −1 (PM3)). A complex involving binding to the C6 substituent described in some earlier works was not found. The calculated lengthening of the ligand C7-N4 bond upon coordination suggests easier Nu − attack at the β-lactam carbon atom, which facilitates the degradation of penicillin. The results also indicate that both methods can be applied to calculations on penicillins. Generally, the PM3 bond lengths are longer than the AM1 values; however, the former reproduces better the first coordination sphere of the Zn(II) ion.

Applicability of the Bacillus stearothermophilus Disc Assay for Penicillin Residues in Casein/Caseinates

Six buffer systems were examined as hydrating solutions for assaying antibiotic residues in bovine casein or caseinates by the qualitative Bacillus stearothermophilus disc assay method. Formic acid and 1% potassium phosphate buffer systems were suitable in that they did not react adversely with the B. stearothermophilus spores or cause degradation of penicillin. With the formic acid buffer, a 20% casein slurry and a 10% caseinate slurry were sufficiently fluid to allow capillary saturation of a 12.7-mm paper disc. Casein and caseinate rehydrated with 1% potassium phosphate buffer were too viscous to permit saturation of a disc. The detectable level in a 20% casein slurry and a 10% caseinate slurry was ≥0.004 IU penicillin G/ml. Casein and caseinate prepared from potassium or procaine penicillin G-contaminated skim milk contained no detectable level of antibiotics as determined by the B. stearothermophilus disc assay method.

PH-dependent effect of magnesium sulfate on the stability of penicillin G potassium solution

The effect of magnesium sulfate on the stability of penicillin G potassium solutions (0.5 mg/mL) was investigated using a stability-indicating high-performance liquid chromatography method. The penicillin G potassium powder buffered with and without citrate was used. Twelve aqueous duplicate penicillin solutions with various concentrations of magnesium sulfate and with or without buffers were prepared and stored at room temperature. Data on clarity, pH values, and HPLC assay results were determined at intervals during the 10-day storage period. The results indicated that the presence of high concentrations of magnesium sulfate in unbuffered penicillin solutions can cause large pH changes and the degradation of penicillin. However, the effect of magnesium sulfate on the stability of penicillin G potassium was negligible in the buffered solutions. Solutions with a constant pH value of 5.6 prepared using 0.1 M acetate buffer with and without magnesium sulfate showed similar apparent first-order degradation after the 10-day storage period at 24 degrees C. During decomposition, the pH values of the unbuffered solutions decreased for three days and then started increasing in most solutions. The degradation of penicillin G potassium by magnesium sulfate in aqueous solutions resulted from decreases in pH values of the solutions.

A kinetic analysis of the acidic degradation of penicillin G and confirmation of penicillamine as a degradation product

Two recently proposed degradation pathways for the acidic degradation of pencillin G were examined by calculating the theoretical time course based on each pathway and examining the fit of the theoretical predictions to the experimental data. A substantial difference in the goodness of fit was observed. The degradation pathway which provided the best fit included penicillamine as a terminal degradation product. This pathway is therefore favoured since penicillamine was also identified as a degradation product of penicillin G by both reversed-phase high pressure liquid chromatography and differential pulse polarography.

Beta-Lactamase activity in human pus.

Pus was obtained from patients with polymicrobial intraabdominal abscesses or polymicrobial empyema. Physical and chemical characteristics of 12 specimens were examined, and bacterial isolates were enumerated. Pus supernatant of six specimens rapidly inactivated penicillin, cephalothin, and cefazolin. Carbenicillin and ticarcillin were similarly degraded by supernatant of certain pus specimens. Cefoxitin, chloramphenicol, and clindamycin were not appreciably inactivated by pus supernatant. Degradation of penicillin and cephalosporin congeners in pus was due to the presence of beta-lactamase, as shown by chemical interaction with nitrocefin, chromatography, and inhibition by the beta-lactamase inhibitor clavulanic acid. Pus supernatant containing beta-lactamase activity reduced the bactericidal activity of carbenicillin against Bacteroides fragilis in whole pus in an abscess model in vitro. Bactericidal activity of clindamycin or cefoxitin was not impaired in pus containing beta-lactamase.

A nuclear magnetic resonance study of the degradation of penicillin G in acidic solution

N.m.r. methods have been used to study the degradation of benzylpenicillin at pH 2.5 and 37 °C. After 100 min three major reaction products, penamaldic acid, penillic acid, and penicilloic acid were detected. By measuring the extent of deuteriation at the C-6 position (the reaction was conducted in DCl–D2O solution) it was shown that most of the penillic acid (65%) and penicilloic acid (70%) had not been formed via a penicillenic acid type intermediate as previously suggested. Eventually the three initial products degraded into penilloic acid without any further deuteriation (estimated from the deuteriation at the C-6 position of penilloic acid): thus penillic acid and penicilloic acid do not degrade via a penicillenic acid intermediate. No penicillamine, benzylpenilloaldehyde, or related products were detected.

NMR Study of Spontaneous Degradation of Penicillin G in Aqueous Solution

Abstract The spontaneous degradation of penicillin G in aqueous solution has been studied using NMR and thin layer chromatography. Correlation NMR spectroscopy was used to follow products which appear at the early stage of degradation. It has been found that in 0.3 M phosphate buffer (pH 7.0, 30 °C) a successive first order degradation penicillin G \xrightarrowk1 penicilloic acid \xrightarrowk2 secondary product is dominant with kinetic constants of k1=0.7×10−2 h−1 and k2=6×10−2 h−1.

Kinetic Analysis of Penicillin Degradation in Acidic Media

Degradation of penicillin in acidic media (pH 2.7) was monitored by high‐pressure liquid chromatography and UV spectroscopy. The effects of temperature, buffer concentration, and ionic strength were examined. A degradation pathway is proposed, and the apparent first-order rate constant and energy of activation were calculated for each reaction. One or more degradation products containing a sulfhydryl group, a functional group often suggested as having a major role in eliciting allergic responses to penicillin therapy, were present throughout the degradation scheme.

Degradation of penicillin G to phenylacetylglycine by D-alanine carboxypeptidase from Bacillus stearothermophilus.

D-Alanine carboxypeptidase from Bacillus stearothermophilus is a membrane-bound enzyme which is inhibited by covalent interaction with penicillin G. The penicilloyl enzyme spontaneously reactivates and simultaneously releases a penicillin G degradation product; 0.2 mumol of the latter was isolated after incubation of 4.2 mumol of [8-14C]penicillin G with 10 g of membrane protein. It was identified as phenylacetylglycine by chromatographic techniques, infrared spectroscopy, and mass spectrometry. A mechanism for the degradation is proposed in which the remaining part of penicillin G would be released as 5,5-dimethyl-delta2-thiazoline-4-carboxylic acid. The implications of this finding are discussed.

Effect of Self-Association on Rate of Penicillin G Degradation in Concentrated Aqueous Solutions

The apparent rate of degradation of penicillin G potassium micellar solutions of 500,000 units/ml, a concentration commonly encountered in vials reconstituted for storage in the refrigerator, was investigated and compared to that of nonmicellar solutions of 8000 units/ml at 25°, ionic strength of 1.1 M, and pH range from 5.0 to 9.5. In the micellar solutions the apparent rate of the H+-catalyzed degradation was increased twofold but that of water- and OH−catalyzed hydrolysis was decreased two- to threefold. Consequently, the pH-rate profile of the micellar solutions was shifted to higher pH values and the pH of minimum degradation was found to be at 7.0 compared to 6.5 for the nonmicellar solution of the same ionic strength. Compared at their respective pH-rate profile minima, micellar penicillin G is 2.5 times as stable as the nonmicellar solution under the conditions of constant pH and ionic strength.

A Student Experiment in Pharmaceutics: Study of the Degradation of Penicillin G in Aqueous Solution

A Student Experiment in Pharmaceutics: Study of the Degradation of Penicillin G in Aqueous Solution