Spectrofluorimetric study of the degradation of α-amino β-lactam antibiotics catalysed by metal ions in methanol†

Abstract

The alpha-aminopenicillins ampicillin and amoxicillin and a cephalosporin, cephalothin, give rise to a fluorescent product when their methanolic solutions are incubated for prolonged time periods. The process also occurs in the presence of the metal ions Cd2+, Co2+ and Zn2+. The effects of the different ions on the emission and excitation wavelengths and the appearance rate of the fluorophore were studied. The appearance of the fluorescent product was zero order for ampicillin and amoxicillin in metal ion-free solution and solutions with Cd2+ and Zn2+, whereas in the presence of Co2+ ion it was first order under the experimental conditions used; for cephalothin it was first order in all cases. Apparent fluorescent compound formation rates were calculated in the zero-order reactions and rate constants in the first-order reactions. The activation energy of the formation reaction of the fluorescent products of amoxicillin and ampicillin was calculated from a study of the reactions at four temperatures; all the values recorded were between 34 and 118 kJ mol-1. As a possible mechanism for the formation of these products, cyclization of the penamaldic derivative of the antibiotic, which is formed in the first stage of the methanolytic reaction, is proposed.

Thermodynamic Study on the Interaction of Ampicillin and Amoxicillin with Ca2+in Aqueous Solution at Different Ionic Strengths and Temperatures

“…Penicillins are a very important class among β-lactamic antibiotics for their considerable activity against bacteria, assuming an essential biological role in the treatment of several diseases. , In recent years, the chemistry of this antibiotic class has aroused significant interest in relation to its biological activities. , It has been known that all β-lactamic antibiotics interact in in vivo systems with several metal cations, forming metal complex species, and their bioavailability can be enhanced or reduced owing to the interaction with metal cations. − Therefore, it is crucial to assess the chemical interaction of penicillins with some important metal cations having biological roles in the human body . The assessment of the interactions between penicillins and a biologically relevant metal cation, such as calcium, is of crucial importance for understanding the in vivo mode of action of these ligands .…”

A Validated HPLC Multichannel DAD Method for the Simultaneous Determination of Amoxicillin and Doxycycline in Pharmaceutical Formulations and Wastewater Samples

“…Amox has better absorption from the intestinal tract, higher capacity for achieving effective concentrations at the receptors, and an enhanced ability to penetrate Gram-negative microorganisms' cellular wall compared to other β-lactam antibiotics [7]. [8,9], voltammetry [10,11], fluorimetry [12,13], microbiological methods [14], capillary electrophoresis [15,16], and high-performance liquid chromatography (HPLC) [2,6,[17][18][19][20][21][22].…”

Interaction of Ampicillin and Amoxicillin with Mn2+: A Speciation Study in Aqueous Solution

“…They are commonly employed as antibiotics owing to the wide spectra mechanisms of action, since they stop bacteria proliferation [11]. It is known that the bioavailability of β-lactam antibiotics is influenced by their interaction in vivo with several metal cations [12][13][14][15][16][17]. For this reason, the assessment of the interactions of these antibiotics with metal cations which play biological roles in the human body is crucial [18].…”