Tetracycline Water Soluble Formulations with Enhanced Antimicrobial Activity

Tetracycline: structural characterization and antimicrobial properties of its water-soluble di-anionic bi-sodium salt

The new water-soluble di-anionic bi-sodium salt of tetracycline (TC), an antibiotic in clinical use, with the formula {[TC]2-[Na+(MeOH)(H2O)] [Na+]·(H2O)}n (TCNa) was synthesized. The compound was characterized by m.p., attenuated total reflectance-Fourier transform infra-red (ATR-FTIR) spectroscopy, and ultraviolet (UV) and proton nuclear magnetic resonance (1H NMR) spectroscopy in the solid state and in solution. The molecular weight (MW) was determined by cryoscopy. The crystal structure of TCNa was also determined by X-ray crystallography. The antibacterial activity of TCNa was evaluated against the bacterial species Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus) by means of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and inhibition zones (IZs). Moreover, the ability of the compound to eradicate biofilm formation was also evaluated. The results are compared with those obtained for the commercially available drug TCH2. The in vitro and in vivo toxicities of TCNa were tested against human corneal epithelial cells (HCECs) and Artemia salina.

Precision Loading and Delivery of Molecular Cargo by Size-Controlled Coacervation of Gold Nanoparticles Functionalized with Elastin-like Peptides

Thermoresponsive elastin-like peptides (ELPs) have been extensively investigated in biotechnology and medicine, but little attention has been paid to the process by which coacervation causes ELP-decorated particles to aggregate. Using gold nanoparticles (AuNPs) functionalized with a cysteine-terminated 96-repeat of the VPGVG sequence (V96-Cys), we show that the size of the clusters that reversibly form above the ELP transition temperature can be finely controlled in the 250 to 930 nm range by specifying the concentration of free V96-Cys in solution and using AuNPs of different sizes. We further find that the localized surface plasmon resonance peak of the embedded AuNPs progressively red-shifts with cluster size, likely due to an increase in particle-particle contacts. We exploit this fine control over size to homogeneously load precise amounts of the dye Nile Red and the antibiotic Tetracycline into clusters of different hydrodynamic diameters and deliver cargos near-quantitatively by deconstructing the aggregates below the ELP transition temperature. Beyond establishing a key role for free ELPs in the agglomeration of ELP-functionalized particles, our results provide a path for the thermally controlled delivery of precise quantities of molecular cargo. This capability might prove useful in combination photothermal therapies and theranostic applications, and to trigger spatially and temporally uniform responses from biological, electronic, or optical systems.

Non-Steroidal Anti-Inflammatory Drugs Loaded to Micelles for the Modulation of Their Water Solubility

The low water solubility of aspirin (ASPH) is well known, creating research challenges regarding both its composition and its delivery. Therefore, the development of new aspirin-based formulations that are water soluble is a research, technological, and financial issue. With the aim to improve the water solubility of ASPH, the micelle of formula SLS@ASPH (SLS = Sodium Lauryl Sulfate) was formed. The Critical Micelle Concentration (CMC) of SLS in the presence of ASPH was determined by ultrasonic velocity, complementary, and transient birefringence measurements. The SLS@ASPH was characterized by the melting point (m.p.), attenuated total reflection spectroscopy (FT-IR-ATR), and X-ray fluorescence spectroscopy (XRF) in a solid state and in a solution by ultraviolet-visible (UV-Vis) and 1H NMR spectroscopies. The SLS/ASPH molar ratio was determined to be 5/1 in SLS@ASPH. The inhibitory activity of SLS@ASPH towards lipoxygenase (LOX), an enzyme that takes part in the inflammation mechanism, was studied. The inhibitory activity of SLS@ASPH against LOX is 3.5-fold stronger than that of free SLS. The in vitro toxicity of the SLS@ASPH was tested on immortalized human keratinocyte (HaCaT) cells.

Antiproliferative Activity of Antibiotics through DNA Binding Mechanism: Evaluation and Molecular Docking Studies

The antiproliferative activity of three antibiotics clinically use, was studied through DNA inhibition mechanisms, ex vivo, in silico and in vitro. The ex vivo interaction of DNA with ciprofloxacin hydrochloride (CIP·HCl), penicillin G sodium salt (PEN·Na), and tetracycline hydrochloride (TC·HCl) was determined by UV-Vis spectra and viscosity measurements. Furthermore, their binding constants (K_b) toward CT-DNA were calculated (K_b = (2.8 ± 0.6) × 10⁴ (CIP·HCl), (0.4 ± 0.1) × 10⁴ (PEN·Na) and (6.9 ± 0.3) × 10⁴ (TC·HCl) Μ^-1). Docking studies on the binding interactions of antibiotics with DNA were performed to rationalize the ex vivo results. The in vitro antiproliferative activity of the antibiotics was evaluated against human breast adenocarcinoma (MCF-7) cells (IC₅₀ values: 417.4 ± 28.2 (CIP·HCl), >2000 (PEN·Na) and 443.1 ± 17.2 (TC·HCl) μΜ). Cell cycle arrest studies confirmed the apoptotic type of MCF-7 cells. The toxicity of the studied agents was in vitro tested against human fetal lung fibroblast cells (MRC-5). The results are compared with the corresponding one for doxorubicin (DOX). Despite their low binding affinity to DNA (K_b) or their different mode of interaction, TC·HCl (anthracycline) or CIP·HCl (quinolones), exhibit notable antiproliferative activity and low toxicity.

The Effect of Alkali Iodide Salts in the Inclusion Process of Phenolphthalein in β-Cyclodextrin: A Spectroscopic and Theoretical Study

The formation of the inclusion complex between β-cyclodextrin (CD) and phenolphthalein (PP) was investigated by means of UV-Vis and FT-IR spectroscopies. The thermodynamic parameters were calculated in the absence and presence of LiI, KI, NaI and CsI iodide salts. The enthalpy change during the formation was found to be negative for all solutions with iodide salts. The enthalpy change was found to decrease in the sequence no salt > NaI > KI> CsI > LiI. Moreover, it was observed that with increasing salt concentration enthalpy decreases monotonically. The interaction between the two molecules was mostly attributed to hydrogen bonding and Van der Waals interactions. Thermodynamic properties revealed that electrostatic forces also contribute when LiI is present in solutions. A molecular docking study was performed to elucidate the docking between phenolphthalein and cyclodextrin. The FT-IR spectra of CD, PP and the CD-PP complex were recorded to establish the formation of the inclusion complex. Semi-empirical and DFT methods were utilized to study theoretically the complexation process and calculate the IR vibrational spectra. The adequate agreement between theoretical and experimental results supports the proposed structural model for the CD-PP complexation.

Removal of tetracycline from wastewater using g-C3N4 based photocatalysts: A review

Tetracycline is currently one of the most consumed antibiotics for human therapy, veterinary purpose, and agricultural activities. Tetracycline worldwide consumption is expected to rise by about more than 30% by 2030. The persistence of tetracycline has necessitated implementing and adopting strategies to protect aquatic systems and the environment from noxious pollutants. Here, graphitic carbon nitride-based photocatalytic technology is considered because of higher visible light photocatalytic activity, low cost, and non-toxicity. Thus, this review highlights the recent progress in the photocatalytic degradation of tetracycline using g-C₃N₄-based photocatalysts. Additionally, properties, worldwide consumption, occurrence, and environmental impacts of tetracycline are comprehensively addressed. Studies proved the occurrence of tetracycline in all water matrices across the world with a maximum concentration of 54 μg/L. Among different g-C₃N₄-based materials, heterojunctions exhibited the maximum photocatalytic degradation of 100% with the reusability of 5 cycles. The photocatalytic membranes are found to be feasible due to easiness in recovery and better reusability. Limitations of g-C₃N₄-based wastewater treatment technology and efficient solutions are also emphasized in detail.

Staphylococcus epidermidis RP62A’s Metabolic Network: Validation and Intervention Strategies

Increasingly, systems biology is gaining relevance in basic and applied research. The combination of computational biology with wet laboratory methods produces synergy that results in an exponential increase in knowledge of biological systems. The study of microorganisms such as Staphylococcus epidermidis RP62A enables the researcher to understand better their metabolic networks, which allows the design of effective strategies to treat infections caused by this species or others. S. epidermidis is the second most commoncause of infection in patients with joint implants, so treating its proliferation seems vital for public health. There are different approaches to the analysis of metabolic networks. Flux balance analysis (FBA) is one of the most widespread streams of research. It allows the study of large metabolic networks, the study their structural properties, the optimization of metabolic flux, and the search for intervention strategies to modify the state of the metabolic network. This work presents the validation of the Staphylococcus epidermidis RP62A metabolic network model elaborated by Díaz Calvo et al. Then, we elaborate further on the network analysis’s essential reactions. The full set of essential reactions (including a previously unobserved one) was computed, and we classified them into equivalence classes. Some proposals to intervene in the network and design knock-outs by studying minimal cut sets of small length are also introduced. In particular, minimal cut sets related to the medium (including exchange reactions associated with medium metabolites) have been computed. In this sense, the unique external MCS (composed of cysteine and sulfate ion) has been found, and all hybrid MCS (based on knocking out both internal and exchange reactions) of length two have also been computed. The paper also points out the possible importance of these new intervention strategies.