The Role of Uptake and Efflux Transporters in the Disposition of Glucuronide and Sulfate Conjugates

Glucuronidation and sulfation are the most typical phase II metabolic reactions of drugs. The resulting glucuronide and sulfate conjugates are generally considered inactive and safe. They may, however, be the most prominent drug-related material in the circulation and excreta of humans. The glucuronide and sulfate metabolites of drugs typically have limited cell membrane permeability and subsequently, their distribution and excretion from the human body requires transport proteins. Uptake transporters, such as organic anion transporters (OATs and OATPs), mediate the uptake of conjugates into the liver and kidney, while efflux transporters, such as multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP), mediate expulsion of conjugates into bile, urine and the intestinal lumen. Understanding the active transport of conjugated drug metabolites is important for predicting the fate of a drug in the body and its safety and efficacy. The aim of this review is to compile the understanding of transporter-mediated disposition of phase II conjugates. We review the literature on hepatic, intestinal and renal uptake transporters participating in the transport of glucuronide and sulfate metabolites of drugs, other xenobiotics and endobiotics. In addition, we provide an update on the involvement of efflux transporters in the disposition of glucuronide and sulfate metabolites. Finally, we discuss the interplay between uptake and efflux transport in the intestine, liver and kidneys as well as the role of transporters in glucuronide and sulfate conjugate toxicity, drug interactions, pharmacogenetics and species differences.

Aluminum Poisoning with Emphasis on Its Mechanism and Treatment of Intoxication

Aluminum poisoning has been reported in some parts of the world. It is one of the global health problems that affect many organs. Aluminum is widely used daily by humans and industries. Residues of aluminum compounds can be found in drinking water, food, air, medicine, deodorants, cosmetics, packaging, many appliances and equipment, buildings, transportation industries, and aerospace engineering. Exposure to high levels of aluminum compounds leads to aluminum poisoning. Aluminum poisoning has complex and multidimensional effects, such as disruption or inhibition of enzymes activities, changing protein synthesis, nucleic acid function, and cell membrane permeability, preventing DNA repair, altering the stability of DNA organization, inhibition of the protein phosphatase 2A (PP2A) activity, increasing reactive oxygen species (ROS) production, inducing oxidative stress, decreasing activity of antioxidant enzymes, altering cellular iron homeostasis, and changing NF-kB, p53, and JNK pathway leading to apoptosis. Aluminum poisoning can affect blood content, musculoskeletal system, kidney, liver, and respiratory and nervous system, and the extent of poisoning can be diagnosed by assaying aluminum compounds in blood, urine, hair, nails, and sweat. Chelator agents such as deferoxamine (DFO) are used in the case of aluminum poisoning. Besides, combination therapies are recommended.

Antibiofilm Activities of Biogenic Silver Nanoparticles Against Candida albicans

Biofilms are microbial colonies that are encased in an organic polymeric matrix and are resistant to antimicrobial treatments. Biofilms can adhere to both biotic and abiotic surfaces, allowing them to colonize medical equipment such as urinary and intravenous catheters, mechanical heart valves, endotracheal tubes, and prosthetic joints. Candida albicans biofilm is the major etiological cause of the pathogenesis of candidiasis in which its unobstructed growth occurs in the oral cavity; trachea, and catheters that progress to systemic infections in the worst scenarios. There is an urgent need to discover novel biofilm preventive and curative agents. In the present investigation, an effort is made to observe the role of cyanobacteria-derived AgNPs as a new antibiofilm agent with special reference to candidiasis. AgNPs synthesized through the green route using Anabaena variabilis cell extract were characterized by UV–visible spectroscopy. The nanoparticles were spherical in shape with 11–15 nm size and were monodispersed. The minimum inhibitory concentration (MIC) of AgNPs was obtained at 12.5 μg/mL against C. albicans. AgNPs 25 μg/mL showed 79% fungal cell membrane permeability and 22.2% ROS production. AgNPs (25 μg/mL) also facilitated 62.5% of biofilm inhibition and degradation. Therefore, AgNPs could be considered as a promising antifungal agent to control biofilm produced by C. albicans.

Effect of Polycation Nanostructures on Cell Membrane Permeability and Toxicity

The interaction of nanometric synthetic materials with cell membranes is one of the key factors determining their possible cytotoxicity. This work investigated the interaction of polycation nanostructures with lipid and...

Aromatic Sulfonamides Including a Sulfonic Acid Tail: New Membrane Impermeant Carbonic Anhydrase Inhibitors for Targeting Selectively the Cancer-Associated Isoforms

We report here a new drug design strategy for producing membrane-impermeant carbonic anhydrase (CA; EC 4.2.1.1) inhibitors selectively targeting the tumor-associated, membrane-bound human CAs IX and XII over off-target cytosolic isoforms. To date, this approach has only been pursued by including permanent positively charged pyridinium type or highly hydrophilic glycosidic moieties into the structure of aromatic sulfonamide CA inhibitors (CAIs). Aliphatic (propyl and butyl) sulfonic acid tails, deprotonated at physiological pH, were thus incorporated onto a benzenesulfonamide scaffold by a common 1,2,3-triazole linker and different types of spacers. Twenty such derivatives were synthesized and tested for their inhibition of target (hCAs IV, IX, and XII) and off-target CAs (hCAs I and II). Most sulfonate CAIs induced a potent inhibition of hCAs II, IX, and XII up to a low nanomolar KI range (0.9–459.4 nM) with a limited target/off-target CA selectivity of action. According to the drug design schedule, a subset of representative derivatives was assessed for their cell membrane permeability using Caco-2 cells and a developed FIA-MS/MS method. The complete membrane impermeability of the sulfonate tailed CAIs (≥98%) validated these negatively charged moieties as being suitable for achieving, in vivo, the selective targeting of the tumor-associated CAs over off-target ones.

A Novel Antibacterial Component and the Mechanisms of an Amaranthus tricolor Leaf Ethyl Acetate Extract against Acidovorax avenae subsp. citrulli

The aim of the present investigation was to determine the active ingredients in Amaranthus tricolor L. leaves and develop a biological pesticide. Organic solvent extraction, column chromatography, liquid chromatography, ODS-C18 reverse elution, Sephadex LH-20 gel filtration, H spectrum, and C spectrum were used to isolate the pure product for an assessment of the agricultural activity and bacteriostatic mechanisms. The results showed that the activity of the crude extract following carbon powder filtration was 1.63-fold that of the non-filtered extract. Further isolation was performed to obtain two pure products, namely, hydroxybenzoic acid (HBA) and benzo[b]furan-2-carboxaldehyde (BFC), and their molecular formulas and molecular weights were C7H6O3 and 138.12, and C9H6O2 and 146.12, respectively. Our study is the first to determine that HBA has bacteriostatic activity (MIC 125 μg/mL) and is also the first to isolate BFC from A. tricolor. The ultrastructure observation results showed that HBA caused the bacteria to become shriveled, distorted, and deformed, as well as exhibit uneven surfaces. After HBA treatment, 70 differentially expressed metabolites were detected in the bacteria, of which 9 were downregulated and 61 were upregulated. The differentially expressed metabolites were mainly strigolactones, organic acids and derivatives, fatty acids, benzene and substituted benzene derivatives, amino acids and associated metabolites, and alcohols and amines. Among all of the downregulated differentially expressed metabolites, MEDP1280 was the most critical, as it participates in many physiological and biochemical processes. The enrichment analysis showed that the differentially expressed metabolites mainly participate in tyrosine metabolism, biosynthesis of amino acids, cysteine and methionine metabolism, and arginine and proline metabolism. Additionally, HBA was found to disrupt cell membrane permeability and integrity, causing the leakage of substances and apoptosis. The physiological and biochemical test results showed that HBA could increase the pyruvate levels in bacteria but could decrease the activities of respiratory enzymes (malate dehydrogenase (MDH) and NADH oxidase) and antioxidant enzymes (superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX)). Inverse molecular docking was used to study the binding between HBA and respiratory and antioxidant enzymes. The results showed that HBA could bind to MDH, NADH oxidase, SOD, and GSH-PX, suggesting that these enzymes may be the effector targets of HBA. Conclusion: The optimal active ingredient in A. tricolor that can inhibit Acidovorax avenae subsp. citrulli was identified as HBA. HBA mainly disrupts the cell membrane, damages the metabolic system, and inhibits respiration and antioxidant enzyme activity to control bacterial growth. These results provide a reference for the further development of biological pesticides.

Autoinducer Analogs Can Provide Bactericidal Activity to Macrolides in Pseudomonas aeruginosa through Antibiotic Tolerance Reduction

Macrolide antibiotics are used in treating Pseudomonas aeruginosa chronic biofilm infections despite their unsatisfactory antibacterial activity, because they display several special activities, such as modulation of the bacterial quorum sensing and immunomodulatory effects on the host. In this study, we investigated the effects of the newly synthesized P. aeruginosa quorum-sensing autoinducer analogs (AIA-1, -2) on the activity of azithromycin and clarithromycin against P. aeruginosa. In the killing assay of planktonic cells, AIA-1 and -2 enhanced the bactericidal ability of macrolides against P. aeruginosa PAO1; however, they did not affect the minimum inhibitory concentrations of macrolides. In addition, AIA-1 and -2 considerably improved the killing activity of azithromycin and clarithromycin in biofilm cells. The results indicated that AIA-1 and -2 could affect antibiotic tolerance. Moreover, the results of hydrocarbon adherence and cell membrane permeability assays suggested that AIA-1 and -2 changed bacterial cell surface hydrophobicity and accelerated the outer membrane permeability of the hydrophobic antibiotics such as azithromycin and clarithromycin. Our study demonstrated that the new combination therapy of macrolides and AIA-1 and -2 may improve the therapeutic efficacy of macrolides in the treatment of chronic P. aeruginosa biofilm infections.

Delirium in Acute Poisoning with 1,4-Butanediol and Its Correction

Delirium complicating regular use of psychoactive substances remains one of the major issues of critical care, toxicology, and psychiatry. However, the pathogenetic mechanisms of delirium development in patients with 1,4-butanediol poisoning have been poorly studied until now.The aim of the study was to reveal specific patterns of delirium in patients with 1,4-butanediol poisoning as well as to study the changes in systemic hemodynamic parameters, respiratory function, and body fluid compartments during the treatment.Material and methods. The study was prospective and treatment-randomized. Forty-eight male patients aged 20 to 45 years with delirium and acute 1,4-butanediol poisoning were enrolled. Of them, 24 patients were administered with succinate-containing drug 40 ml daily, 24 patients received standard treatment without antihypoxic agents. We studied the evolution of delirium, changes in anaerobic metabolism parameters, systemic hemodynamics, respiratory function, and the volume of fluid compartments. Impedance measurement method adjusted for interference was used in the study.Results. At the «peak» of delirium (days 1–3), the hyperdynamic circulation, increased systemic arterial tone, stroke output, respiratory function parameters, and metabolic lactate acidosis were recorded. A decrease in total fluid volume and extracellular fluid volume was clearly observed during day 1 of intoxication delirium along with increased permeability of cell membranes. On day 3 of delirium, a decrease in intracellular fluid volume and increase in extracellular fluid volume were noted. After the cytoflavin administration, shorter delirium duration (7.5 [6; 8] days), more rapid correction of lactate acidosis, stabilization of respiratory parameters and stabilization of cell membrane permeability by day 5 were found. In the control group, delirium persisted for up to 14 [11; 15] days (z=-5.9; P=0.00011) with more frequent development of complications such as nosocomial pneumonia (χ2=8.4, P<0.001).Conclusion. The severity of delirium in acute poisoning with 1,4-butanediol was associated with metabolic lactate acidosis, changes in systemic hemodynamics and pulmonary function. A positive effect of adjunctive antihypoxic therapy with succinate-containing agent on cardio-respiratory parameters, cell membrane permeability, water balance due to elimination of tissue hypoxia and prompt switching to tissue aerobic metabolism has been found.

Purification and Characterization of Plantaricin YKX and Assessment of Its Inhibitory Activity Against Alicyclobacillus spp.

Consumers prefer natural over synthetic chemical preservatives on a food label. Therefore, it is crucial to ensure the safety and efficacy of such natural preservatives. The emergence of heat-resistant spore-forming Alicyclobacillus spp. has been associated with spoilage problems in the fruit juice industry. Herein, a bacteriocin-producing stain YKX was isolated from the traditional pickles in Hanzhong City, China, and it was identified as Lactobacillus plantarum by morphological, biochemical, physiological, and genotypic features. A stable bacteriocin, plantaricin YKX, was isolated, purified, and tested for its efficacy against Alicyclobacillus acidoterrestris. Plantaricin YKX is a 14-amino acid peptide (Lys-Tyr-Gly-Asn-Gly-Leu-Ser-Arg-Ile-Phe-Ser-Ala-Leu-Lys). Its minimal inhibitory concentrations (MICs) against the tested bacterial and fungal strains were ranged from 16 to 64 μg/mL. It is thermostable and active at pH 3–8. The flow cytometry data and microscopic observations suggested that plantaricin YKX can augment cell membrane permeability, induce potassium ion leakage and pore formation, and disrupt cell membranes. It also affects spore germination and guaiacol production of A. acidoterrestris, probably due to upregulation of the luxS gene linked to quorum sensing.