Acid–base properties of penicillins and cephalosporins (a review)

Determination of the microscopic acid dissociation constant of piperacillin and identification of dissociated molecular forms

For amphoteric ß-lactam antibiotics, the acid dissociation constant (pK a) is a fundamental parameter to characterize physicochemical and biochemical properties of antibiotics and to predict persistence and removal of drugs. pK a of piperacillin (PIP) is determined by potentiometric titration with a glass electrode. Electrospray ionization mass spectrometry (ESI-MS) is creatively applied to verify the reasonable pK a value at every dissociation step. Two microscopic pK a values (3.37 ± 0.06 and 8.96 ± 0.10) are identified and attributed to the direct dissociation of the carboxylic acid functional group and one secondary amide group, respectively. Different from other ß-lactam antibiotics, PIP presents a dissociation pattern where direct dissociation is involved instead of protonation dissociation. Moreover, the degradation tendency of PIP in an alkaline solution may alter the dissociation pattern or dismiss the corresponding pK a of the amphoteric ß-lactam antibiotics. This work offers a reliable determination of the acid dissociation constant of PIP and a clear interpretation of the effect of stability of antibiotics on the dissociation process.

How do freshwater microalgae and cyanobacteria respond to antibiotics?

Antibiotic pollution is an emerging environmental challenge. Residual antibiotics from various sources, including municipal and industrial wastewater, sewage discharges, and agricultural runoff, are continuously released into freshwater environments, turning them into reservoirs that contribute to the development and spread of antibiotic resistance. Thus, it is essential to understand the impacts of antibiotic residues on aquatic organisms, especially microalgae and cyanobacteria, due to their crucial roles as primary producers in the ecosystem. This review summarizes the effects of antibiotics on major biological processes in freshwater microalgae and cyanobacteria, including photosynthesis, oxidative stress, and the metabolism of macromolecules. Their adaptive mechanisms to antibiotics exposure, such as biodegradation, bioadsorption, and bioaccumulation, are also discussed. Moreover, this review highlights the important factors affecting the antibiotic removal pathways by these organisms, which will promote the use of microalgae-based technology for the removal of antibiotics. Finally, we offer some perspectives on the opportunities for further studies and applications.

New quantification method for monitoring eighteen L-amino acids levels in schizophrenic patients by high-performance liquid chromatography coupled to tandem quadrupole mass spectrometer

A fast, uncomplicated, sensitive, and fully validated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method has been developed for estimating L-amino acids in the plasma of schizophrenic patients. The gradient-elution chromatographic method was implemented with the Luna® PFP column (50 × 2.0 mm, 5-μm), and a mobile phase of 0.1% formic acid in water and methanol was used. The intraday and interday variability of the L-amino acids were less than 13.11%, and their accuracy ranged from 85.14 - 116.75% at the quality control levels and the lower limit of quantification (LLOQ) ranged from 2.5 - 15 nM. The extraction efficiency (apparent recovery) of amino acids from healthy plasma was employed by spiking the plasma with standard amino acids at the quality control levels. Their percentage recoveries ranged from 80.4% to 119.94%. Our method has a short run time and fast sample preparation compared with existing methods, which are suffered from long preparative steps and/or time-consuming analysis, restricted reagents, and suboptimal performance characteristics presently available technologies. Therefore, the proposed HPLC-MS/MS method was effectively applied for monitoring the L-amino acids in the plasma of schizophrenic patients and healthy volunteers.

Strategies to Improve the Biosynthesis of β-Lactam Antibiotics by Penicillin G Acylase: Progress and Prospects

β-Lactam antibiotics are widely used anti-infection drugs that are traditionally synthesized via a chemical process. In recent years, with the growing demand for green alternatives, scientists have turned to enzymatic synthesis. Penicillin G acylase (PGA) is the second most commercially used enzyme worldwide with both hydrolytic and synthetic activities toward antibiotics, which has been used to manufacture the key antibiotic nucleus on an industrial level. However, the large-scale application of PGA-catalyzed antibiotics biosynthesis is still in the experimental stage because of some key limitations, such as low substrate concentration, unsatisfactory yield, and lack of superior biocatalysts. This paper systematically reviews the strategies adopted to improve the biosynthesis of β-lactam antibiotics by adjusting the enzymatic property and manipulating the reaction system in recent 20 years, including mining of enzymes, protein engineering, solvent engineering, in situ product removal, and one-pot reaction cascade. These advances will provide important guidelines for the future use of enzymatic synthesis in the industrial production of β-lactam antibiotics.

Polythiophene for Near Full pH Photo-antimicrobial

Microbial infections are currently one of the world’s major public health cares, the evolution of which has resulted in the development of multiple tolerances (not just the drug or antibiotic...

Antibiotic-metal complexes in wastewaters: fate and treatment trajectory

Unregulated usage, improper disposal, and leakage from pharmaceutical use and manufacturing sites have led to high detection levels of antibiotic residues in wastewater and surface water. The existing water treatment technologies are insufficient for removing trace antibiotics and these residual antibiotics tend to interact with co-existing metal ions and form antibiotic-metal complexes (AMCs) with altered bioactivity profile and physicochemical properties. Typically, antibiotics, including tetracyclines, fluoroquinolones, and sulphonamides, interact with heavy metals such as Fe²⁺, Co²⁺, Cu²⁺, Ni²⁺, to form AMCs which are more persistent and toxic than parent compounds. Although many studies have reported antibiotics detection, determination, distribution and risks associated with their environmental persistence, very few investigations are published on understanding the chemistry of these complexes in the wastewater and sludge matrix. This review, therefore, summarizes the structural features of both antibiotics and metals that facilitate complexation in wastewater. Further, this work critically appraises the treatment methods employed for antibiotic removal, individually and combined with metals, highlights the knowledge gaps, and delineates future perspectives for their treatment.

Activated Olive Stones as a Low-Cost and Environmentally Friendly Adsorbent for Removing Cephalosporin C from Aqueous Solutions

In this paper, we describe the removal of cephalosporin C (CPC) from aqueous solutions by adsorption onto activated olive stones (AOS) in a stirred tank. For comparative purposes, several experiments of adsorption onto commercial granular activated carbon were carried out. A quantum study of the different species of cephalosporin C that, depending on the pH, exist in aqueous solution pointed to a favorable mass transfer process during adsorption. Activated olive stones were characterized by SEM, EDX and IR techniques and their pHzc was determined. A 10-3 M HCl cephalosporin C solution has been selected for the adsorption experiments because at the pH of that solution both electrostatic and hydrogen bond interactions are expected to be established between the adsorbate and the adsorbent. The adsorption process is best described by the Freundlich isotherm model and the pseudo-second-order kinetic model, while the adsorption mechanism is mainly controlled by film diffusion. Under the conditions studied, the adsorption process is of a physical nature, endothermic and spontaneous. Comparison of the adsorption results obtained in this paper with those of other authors shows that the efficiency of AOS is 20% of that of activated carbon but 65% higher than that of the XAD-2 adsorbent. Considering its low price, abundance, easy accessibility and eco-compatibility, the use of activated olive stones as adsorbents for the removal of emerging pollutants from aqueous solutions represents an interesting possibility from both the economic and the environmental points of view.

Gel-based Microemulsion Design and Evaluation for Topical Application of Rivastigmine

OBJECTIVE

The aim of the present study was to design nanocarriers for the topical application of rivastigmine.

METHODS

The effect of cosurfactants, hydrophilic gel and loading amount on the permeability of rivastigmine through rat skin was evaluated. Skin irritation tests and stability tests were performed to evaluate the utility of tested formulations.

RESULTS

The results showed that the microemulsion formation and characteristics of drug-loaded formulations were related to many parameters of the components. When using microemulsion systems as a vehicle, the permeation rate remarkably increased about 13.2~24.3-fold and the lag time was significantly shortened from 24 h to 4.7 h. Formulations containing a cosurfactant of Diethylene Glycol Monobutyl Ether (DEGBE) showed higher enhancement effect, while increasing the loading dose from 0.5% to 5% further increased the flux about 2.1-fold and shortened the lag time.

CONCLUSION

The drug-loaded experimental formulation did not cause skin irritation and had good stability at 20ºC and 40ºC storage for at least 3 months. The result showed that gel-based microemulsion formulation could be a promising approach for topical administration.

Classical and New Pharmaceutical Uses of Bacterial Penicillin G Acylase

BACKGROUND

β-lactam antibiotics are the most used worldwide for the treatment of bacterial infections. The consumption of these classes of drugs is high, and it is increasing around the world. To date, the best way to produce them is using penicillin G Acylase (PGA) as a biocatalyst.

OBJECTIVE

This manuscript offers an overview of the most recent advances in the current tools to improve the activity of the PGA and its pharmaceutical application.

RESULTS

Several microorganisms produce PGA, but some bacterial strains represent the primary source of this enzyme. The activity of bacterial PGA depends on its adequate expression and carbon or nitrogen source, as well as a specific pH or temperature depending on the nature of the PGA. Additionally, the PGA activity can be enhanced by immobilizing it to a solid support to recycle it for a prolonged time. Likewise, PGAs more stable and with higher activity are obtained from bacterial hosts genetically modified.

CONCLUSION

PGA is used to produce b-lactam antibiotics. However, this enzyme has pharmaceutical potential to be used to obtain critical molecules for the synthesis of anti-tumor, antiplatelet, antiemetic, antidepressive, anti-retroviral, antioxidant, and antimutagenic drugs.

Quantitative analysis of cefazolin sodium in lyophilized powder by infrared spectrophotometry: Green, low cost, fast and effective

Cefazolin sodium is a broad-spectrum antibiotic used in the treatment of infectious diseases in humans and in the surgical prophylaxis. Thus, since a considerable number of people have access to this drug, it is of great interest of quality control. The aim of this study was development and validation of a green method by Fourier-Transform Infrared (FT-IR) transmission spectrophotometry for the quantification of cefazolin sodium in lyophilized powder. This technique is widely used in the pharmaceutical industry due to its ease of execution, low cost, safety and high precision and accuracy. It has been employed in the quality control routine of numerous pharmaceuticals in order to identify them and quantify their active principles. The proposed method was completely validated according ICH guidelines, showing selectivity, accuracy, precision, robustness and linearity. It was linear over the concentration range of 0.4-1.7 mg with correlation coefficient 0.999, limits of detection and quantification of 0.017 mg and 0.052 mg, respectively, precise, accurate and robust when changes in the time, pressure and mark of potassium bromide were carried out during the preparation of the pellets. The proposed method was successfully applied to the qualitative and quantitative quality control of cefazolin sodium in lyophilized powder. In addition, the method is considered green, clean and sustainable since it uses only a single reagent; it is a fast, low-cost and environmentally friendly method.

Flucloxacillin: A Review of Characteristics, Properties and Analytical Methods

Bacterial resistance is a growing and worrying factor. The high reproducibility of these resistant microorganisms tends to influence the development of new drugs and research related to product quality control. Among the existing antimicrobials, flucloxacillin (FLU) was designed for oral and injectable administration with bactericidal activity. FLU sodium is the form used in pharmaceutical formulations. It is an antimicrobial resistant against penicillinase, an enzyme responsible for cleaving the beta-lactam ring of penicilins, which leads to inactivity of the drug. Qualitative and quantitative analyzes are essential to ensure quality of pharmaceuticals and health of the population. It is important that quality control is effective and appropriate, only then we can win the battle against microbial resistance. In this work, we want to highlight tthe characteristics of FLU as an important antibiotic and methods for the determination of FLU in pharmaceutical products and biological matrices. Among the analytical methods described in the literature for the determination of FLU, high performance liquid chromatography (HPLC) stands out. Anyway, this method uses toxic solvents (e.g. acetonitrile) long columns, which provide long runs, as well as produces large amounts of waste. Currently, the priority changed to develop ecologically correct, conscious and sustainable methods. This new view on analytical methods should be applied to FLU analyzes and used to develop and improve existing methods.

β-Lactam antibiotic-degrading enzymes from non-pathogenic marine organisms: a potential threat to human health

Metallo-β-lactamases (MBLs) are a family of Zn(II)-dependent enzymes that inactivate most of the commonly used β-lactam antibiotics. They have emerged as a major threat to global healthcare. Recently, we identified two novel MBL-like proteins, Maynooth IMipenemase-1 (MIM-1) and Maynooth IMipenemase-2 (MIM-2), in the marine organisms Novosphingobium pentaromativorans and Simiduia agarivorans, respectively. Here, we demonstrate that MIM-1 and MIM-2 have catalytic activities comparable to those of known MBLs, but from the pH dependence of their catalytic parameters it is evident that both enzymes differ with respect to their mechanisms, with MIM-1 preferring alkaline and MIM-2 acidic conditions. Both enzymes require Zn(II) but activity can also be reconstituted with other metal ions including Co(II), Mn(II), Cu(II) and Ca(II). Importantly, the substrate preference of MIM-1 and MIM-2 appears to be influenced by their metal ion composition. Since neither N. pentaromativorans nor S. agarivorans are human pathogens, the precise biological role(s) of MIM-1 and MIM-2 remains to be established. However, due to the similarity of at least some of their in vitro functional properties to those of known MBLs, MIM-1 and MIM-2 may provide essential structural insight that may guide the design of as of yet elusive clinically useful MBL inhibitors.