The Role of Efflux Pumps and Environmental pH in Bacterial Multidrug Resistance.

Background/aim: One of the most studied bacterial resistance mechanisms is the resistance related to multidrug efflux pumps. In our study the pump activity of the Escherichia coli K-12 AG100 strain expressing the AcrAB-TolC pump system was investigated at pH 7 and pH 5 in the presence of the efflux pump inhibitor (EPI) promethazine (PMZ).

Materials And Methods: The EPI activity was assessed by real-time fluorimetry.

Possible Biological and Clinical Applications of Phenothiazines.

Phenothiazines have been used in many areas of medicine, mainly in psychopharmacology. These compounds are able to effectively inhibit dopamine, histamine, serotonin, acetylcholine, and α-adrenergic receptors; thus, their effect and side-effect profiles are extremely diverse. Besides their antipsychotic activity, phenothiazines have a significant antimicrobial effect as well, since they can enhance the bactericidal function of macrophages and inhibit efflux pumps.

New Roads Leading to Old Destinations: Efflux Pumps as Targets to Reverse Multidrug Resistance in Bacteria.

Multidrug resistance (MDR) has appeared in response to selective pressures resulting from the incorrect use of antibiotics and other antimicrobials. This inappropriate application and mismanagement of antibiotics have led to serious problems in the therapy of infectious diseases. Bacteria can develop resistance by various mechanisms and one of the most important factors resulting in MDR is efflux pump-mediated resistance.

Thioridazine: A Non-Antibiotic Drug Highly Effective, in Combination with First Line Anti-Tuberculosis Drugs, against Any Form of Antibiotic Resistance of Mycobacterium tuberculosis Due to Its Multi-Mechanisms of Action.

This review presents the evidence that supports the use of thioridazine (TZ) for the therapy of a pulmonary tuberculosis infection regardless of its antibiotic resistance status. The evidence consists of in vitro and ex vivo assays that demonstrate the activity of TZ against all encountered (Mtb) regardless of its antibiotic resistance phenotype, as well as in vivo as a therapy for mice infected with multi-drug resistant strains of Mtb, or for human subjects infected with extensively drug resistant (XDR) Mtb. The mechanisms of action by which TZ brings about successful therapeutic outcomes are presented in detail.

The Anticancer Activity of the Old Neuroleptic Phenothiazine-type Drug Thioridazine.

Thioridazine (TZ), an antipsychotic drug, renders multidrug-resistant (MDR) cancer cells susceptible to cytotoxic agents to which they were initially resistant, has anti-prolilferative activity and apoptosis-inducing properties in various tumor cell lines and cancer stem cells. Whereas the anti-proliferative activity takes place at high concentrations that ensure the intercalation of the compound between nucleic bases (especially rich in G/C bases), much lower concentrations inhibit the export function of the ABCB1 (P-glycoprotein), which is responsible for the MDR phenotype of the cancer cell. The co-administration of TZ with doxorubicin inhibits efflux of doxorubicin and, hence, increases the intracellular concentration of anticancer drug.

Identification of Important Compounds Isolated from Natural Sources that Have Activity Against Multidrug-resistant Cancer Cell Lines: Effects on Proliferation, Apoptotic Mechanism and the Efflux Pump Responsible for Multi-resistance Phenotype.

The focus of this mini-review is to identify non-toxic compounds isolated from natural sources (plants) that exhibit specific activity against efflux pumps of specific multidrug-resistant (MDR) cancer cell lines, inhibit proliferation of the MDR cancer cell lines and inhibit the activity of overexpressed efflux pumps of the MDR cancer cell line.

Identification of selenocompounds with promising properties to reverse cancer multidrug resistance.

In previous studies, 56 novel selenoesters and one cyclic selenoanhydride with chemopreventive, antiproliferative and cytotoxic activity were described. Herein, the selenoanhydride and selected selenoesters were evaluated for their ability to reverse the cancer multidrug resistance (MDR) using the ABCB1 efflux pump inhibition assay in mouse MDR T-lymphoma cells. Results showed that the selenoanhydride (1) and the selenoesters with ketone terminal fragments (9-11) exerted (1.

Thioridazine Alters the Cell-Envelope Permeability of Mycobacterium tuberculosis.

The increasing occurrence of multidrug resistant tuberculosis exerts a major burden on treatment of this infectious disease. Thioridazine, previously used as a neuroleptic, is active against extensively drug resistant tuberculosis when added to other second- and third-line antibiotics. By quantitatively studying the proteome of thioridazine-treated Mycobacterium tuberculosis, we discovered the differential abundance of several proteins that are involved in the maintenance of the cell-envelope permeability barrier.

Ion Channel Blockers as Antimicrobial Agents, Efflux Inhibitors, and Enhancers of Macrophage Killing Activity against Drug Resistant Mycobacterium tuberculosis.

Given the ability of M. tuberculosis to survive as an intracellular pathogen and its propensity to develop resistance to the existing antituberculosis drugs, its treatment requires new approaches. Here the antimycobacterial properties of verapamil, thioridazine, chlorpromazine, flupenthixol and haloperidol were investigated against a panel of drug resistant M.

Fluorimetric Methods for Analysis of Permeability, Drug Transport Kinetics, and Inhibition of the ABCB1 Membrane Transporter.

The cell membrane P-glycoprotein (P-gp; MDR1, ABCB1) is an energy-dependent efflux pump that belongs to the ATP-binding cassette (ABC) family of transporters, and has been associated with drug resistance in eukaryotic cells. Multidrug resistance (MDR) is related to an increased expression and function of the ABCB1 (P-gp) efflux pump that often causes chemotherapeutic failure in cancer. Modulators of this efflux pump, such as the calcium channel blocker verapamil (VP) and cyclosporine A (CypA), can reverse the MDR phenotype but in vivo studies have revealed disappointing results due to adverse side effects.

Imidazolidine-4-one derivatives in the search for novel chemosensitizers of Staphylococcus aureus MRSA: synthesis, biological evaluation and molecular modeling studies.

A series of amine derivatives of 5-aromatic imidazolidine-4-ones (7-19), representing three subgroups: piperazine derivatives of 5-arylideneimidazolones (7-13), piperazine derivatives of 5-arylideneimidazolidine-2,4-dione (14-16) and primary amines of 5-naphthyl-5-methylimidazolidine-2,4-diones (17-19), was evaluated for their ability to improve antibiotics effectiveness in two strains of Gram-positive Staphylococcus aureus: ATCC 25923 (a reference strain) and MRSA (methicillin resistant S. aureus) HEMSA 5 (a resistant clinical isolate). The latter compounds (17-19) were obtained by 4-step synthesis using Bucherer-Bergs condensation, two-phase bromoalkylation and Gabriel reactions.

Ecdysteroids sensitize MDR and non-MDR cancer cell lines to doxorubicin, paclitaxel, and vincristine but tend to protect them from cisplatin.

Ecdysteroids, analogs of the insect molting hormone, are known for their various mild, nonhormonal bioactivities in mammals. Previously, we reported that less-polar ecdysteroids can modulate the doxorubicin resistance of a multidrug resistant (MDR) mouse lymphoma cell line expressing the human ABCB1 transporter. Here, we describe the ability of 20-hydroxyecdysone (1) and its mono- (2) and diacetonide (3) derivatives to sensitize various MDR and non-MDR cancer cell lines towards doxorubicin, paclitaxel, vincristine, or cisplatin.

Reversal of ABCB1-related Multidrug Resistance of Colonic Adenocarcinoma Cells by Phenothiazines.

Background: The most common mechanism that reduces the efficacy of anticancer agents is overexpression of ATP-binding cassette (ABC) drug transporters. Phenothiazines and structurally-related compounds can sensitize multidrug-resistant (MDR) cells to chemotherapeutics.

Materials And Methods: Phenothiazine derivatives were investigated regarding their anticancer and MDR-reversing effect on colonic adenocarcinoma cells.

Characterization of mixtures of compounds produced in chlorpromazine aqueous solutions by ultraviolet laser irradiation: their applications in antimicrobial assays.

The study reports an investigation of the photoproducts obtained by exposure of chlorpromazine hydrochloride in ultrapure water (concentration 2 mg/mL) to a 266-nm laser beam obtained by fourth harmonic generation from a Nd:YAG laser (6-ns full time width at half maximum, 10-Hz pulse repetition rate). The photoproducts were analyzed by steady-state UV-Vis absorption, laser-induced fluorescence, Fourier transform infrared spectroscopy, and liquid chromatography-tandem time-of-flight mass spectroscopy. Two figures showing pathways that take place during irradiation for obtaining the final products are shown.

Rapid, laser-induced conversion of 20-hydroxyecdysone - a follow-up study on the products obtained.

We have recently reported the set-up of an experimental system for the laser-induced photochemical modification of bioactive substances, where two ecdysteroids, 20-hydroxyecdysone (20E) and its diacetonide derivative served as probes. As a direct continuation of our previous work, three new compounds together with five other ecdysteroid derivatives, have been identified from the novel, laser-induced photo-transformation reaction of 20E. The structures and NMR signal assignment were established by comprehensive one- and two-dimensional NMR spectroscopy supported by mass spectroscopy.

Multidrug resistance reversing activity of newly developed phenothiazines on P-glycoprotein (ABCB1)-related resistance of mouse T-lymphoma cells.

Background: Phenothiazines have anticancer properties and are able to reverse the multidrug resistance of neoplastic cells by inhibiting the ATP-binding cassette, sub-family B (MDR/TAP), member 1 protein (ABCB1 or P-glycoprotein) activity.

Materials And Methods: A series of new phenothiazine derivatives was investigated regarding their ABCB1-modulating effect on multidrug resistant mouse T-lymphoma cells by rhodamine 123 accumulation assay and real-time ethidium bromide accumulation assay.

Results: The phenothiazine derivatives exhibited a potent anticancer effect on the parental cell line and on its multidrug-resistant mouse T-lymphoma subline overexpressing the ABCB1 transporter.

Mechanisms by which thioridazine in combination with antibiotics cures extensively drug-resistant infections of pulmonary tuberculosis.

Advances recently introduced into the Clinical Mycobacteriology Laboratory of the Institute of Hygiene and Tropical Medicine, such that a multi-drug resistant infection of pulmonary tuberculosis (MDR TB) can be identified within one day of receiving the sputum specimen, have greatly contributed to the reduction of the frequency of these infections. However, approximately 50% of reduced infections exhibit a phenotype that is consistent with that presented by an extensively drug-resistant (XDR) infection. More effective agents were required and hence attention was attributed to the possibility that the old neuroleptic phenothiazine thioridazine (TZ), previously shown to inhibit the growth of all encountered strains of Mycobacterium tuberculosis (Mtb) regardless of their antibiotic resistance profile, could be eventually used for therapy of problematic MDR/XDR TB infections.

Efflux pumps of Gram-negative bacteria: what they do, how they do it, with what and how to deal with them.

This review discusses the relationship of the efflux pump (EP) system of Gram-negative bacteria to other antibiotic resistance mechanisms of the bacterium such as quorum sensing, biofilms, two component regulons, etc. The genetic responses of a Gram-negative to an antibiotic that render it immune to an antibiotic are also discussed. Lastly, the methods that have been developed for the identification of bacteria that over-express their EP system are presented in detail.

Synthesis and structure-activity relationships of novel ecdysteroid dioxolanes as MDR modulators in cancer.

Ecdysteroids, molting hormones of insects, can exert several mild, non-hormonal bioactivities in mammals, including humans. In a previous study, we have found a significant effect of certain derivatives on the ABCB1 transporter mediated multi-drug resistance of a transfected murine leukemia cell line. In this paper, we present a structure-activity relationship study focused on the apolar dioxolane derivatives of 20-hydroxyecdysone.

The mechanism by which the phenothiazine thioridazine contributes to cure problematic drug-resistant forms of pulmonary tuberculosis: recent patents for "new use".

At this moment, over half million patients suffer from multi-drug resistant tuberculosis (MDR-TB) according to the data from the WHO. A large majority is terminally ill with essentially incurable pulmonary tuberculosis. This herein mini-review provides the experimental and observational evidence that a specific phenothiazine, thioridazine, will contribute to cure any form of drug-resistant tuberculosis.

Effect of thioridazine stereoisomers on the drug accumulation of mouse lymphoma and human prostate cancer cell lines in vitro.

Background: Cancer cells become refractory to chemotherapy as a consequence of their overexpression of multidrug transporters.

Materials And Methods: The anticancer and multidrug resistance (MDR) reversal effects of the racemic form and the two enantiomers of thoridazine were investigated on a mouse T-lymphoma cell line over-expressing the ATP-binding cassette, subfamily-B (MDR/TAP), member 1 (ABCB1) transporter (also known as P-glycoprotein) and on human PC3 prostate cancer cell line by 3-(4.5-dimethylthiazolyl-2)-2.

The in vitro activity of products formed from exposure of chlorpromazine to a 266 nm laser beam against species of mycobacteria of human interest.

Chlorpromazine (CPZ) was exposed to a 266 nm laser beam for different periods of time ranging from minutes to 24 h. At intervals, the products from irradiation were evaluated by thin-layer chromatography (TLC) and evaluated for their activity against mycobacteria of human interest (Mycobacterium tuberculosis, M. avium, M.

Effects of two disiloxanes ALIS-409 and ALIS-421 on chemoprevention in model experiments.

Morpholino-disiloxane (ALIS-409) and piperazino-disiloxane (ALIS-421) compounds were developed as inhibitors of multidrug resistance of various types of cancer cells. In the present study, the effects of ALIS-409 and ALIS-421 compounds were investigated on cancer promotion and on co-existence of tumor and normal cells. The two compounds were evaluated for their inhibitory effects on Epstein-Barr virus immediate-early antigen (EBV-EA) expression induced by tetradecanoyl-phorbol-acetate (TPA) in Raji cell cultures.

A Simple Method for Assessment of MDR Bacteria for Over-Expressed Efflux Pumps.

It is known that bacteria showing a multi-drug resistance phenotype use several mechanisms to overcome the action of antibiotics. As a result, this phenotype can be a result of several mechanisms or a combination of thereof. The main mechanisms of antibiotic resistance are: mutations in target genes (such as DNA gyrase and topoisomerase IV); over-expression of efflux pumps; changes in the cell envelope; down regulation of membrane porins, and modified lipopolysaccharide component of the outer cell membrane (in the case of Gram-negative bacteria).