Sodium Deoxycholate Market Share | Trends & Analysis ...

Sodium Deoxycholate Market Size Projection

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The Sodium Deoxycholate market is projected to experience significant growth in , driven by technological advancements, increasing consumer demand, and expanding applications across various industries. Key factors contributing to this growth include innovative product developments, strategic partnerships, and rising investments in research and development. The market is expected to reach a substantial valuation, reflecting a strong compound annual growth rate (CAGR). Additionally, emerging markets and the adoption of Sodium Deoxycholate solutions in new sectors are anticipated to further accelerate market expansion.

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Key Points Sodium Deoxycholate Market Size Projection in

1. Technological Advancements:Continuous innovation and improved functionalities in Sodium Deoxycholate products are crucial drivers of market growth. Companies are investing in cutting-edge technologies to enhance product performance, reliability, and user experience. These advancements not only attract new customers but also retain existing ones by meeting evolving demands.
2. Increasing Consumer Demand:There is a growing preference for Sodium Deoxycholate solutions among consumers, fueled by their effectiveness, efficiency, and convenience. As more individuals and businesses recognize the benefits of Sodium Deoxycholate, the market is expected to see a substantial rise in demand, contributing to overall growth.
3. Expanding Applications:The adoption of Sodium Deoxycholate across various industries, including healthcare, finance, and manufacturing, is broadening the market's scope. Each sector leverages Sodium Deoxycholate solutions to optimize operations, reduce costs, and improve service delivery, which in turn drives market expansion.
4. Strategic Partnerships:Collaborations and alliances are essential for enhancing market reach and capabilities. Strategic partnerships enable companies to combine expertise, share resources, and access new markets more effectively, fostering growth and innovation within the Sodium Deoxycholate market.
5. R&D Investments: Increased funding for research and development is pivotal in driving product innovation. Companies are allocating substantial budgets to R&D to develop new Sodium Deoxycholate solutions, improve existing ones, and stay competitive in a rapidly evolving market.
6. Market Valuation:The Sodium Deoxycholate market is projected to reach a significant financial milestone by the end of . This valuation reflects the market's robust growth prospects and the increasing adoption of Sodium Deoxycholate solutions worldwide.
7. CAGR:The strong compound annual growth rate (CAGR) indicates robust market growth. A high CAGR signifies sustained expansion and increasing revenue over the forecast period, highlighting the market's potential.
8. Emerging Sodium Deoxycholate Market: Rising adoption in developing regions is contributing significantly to market expansion. Emerging markets offer vast opportunities due to their large populations, improving economic conditions, and growing technological infrastructure, making them key targets for Sodium Deoxycholate market growth.
9. New Sector Adoption: The penetration of Sodium Deoxycholate solutions into previously untapped sectors is creating new growth avenues. As more industries discover the advantages of Sodium Deoxycholate market, the market will continue to diversify and expand, reaching new heights in and beyond.

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Sodium Deoxycholate Market Segmentation Analysis

Segmentation analysis involves dividing the market into distinct groups based on certain criteria such as type and application. This helps in understanding the market dynamics, targeting specific customer groups, and devising tailored marketing strategies.

By Type

• Sodium Deoxycholate-based
• Phosphatidylcholine-based

By Application

• Clinic
• Beauty Salon
• Others

Major companies

• Koru Pharmaceuticals
• Marllor Biomedical
• Allergan Aesthetics
• Laboratorio Innoaesthetics
• LOVE Cosmedical
• DEXLEVO Aesthetic

Global Sodium Deoxycholate Market Regional Analysis

North America:

• Major Players: United States, Canada
• Strengths: Robust economy, technological advancements, strong consumer base with high purchasing power
• Opportunities: Innovation, market leadership, consumer demand
• Challenges: Competition, regulatory environment

Europe:

• Major Players: United Kingdom, Germany, France, Italy
• Strengths: Mature market, well-established infrastructure, consumer preferences
• Opportunities: Market stability, brand recognition, innovation
• Challenges: Saturation, regulatory compliance

Asia-Pacific:

• Major Players: China, Japan, India, South Korea
• Strengths: Rapidly growing market, large population, rising disposable income, urbanization
• Opportunities: Expansion, market penetration, diverse consumer base
• Challenges: Cultural differences, regulatory complexities

Latin America:

• Major Players: Brazil, Mexico, Argentina
• Strengths: Opportunities for growth, emerging market dynamics
• Opportunities: Untapped markets, consumer demand
• Challenges: Economic fluctuations, political instability

Middle East and Africa:

• Major Players: UAE, Saudi Arabia, South Africa, Nigeria
• Strengths: Emerging markets, economic diversification, urbanization, young population
• Opportunities: Market development, investment potential
• Challenges: Infrastructure development, geopolitical risks

Frequently Asked Questions (FAQ in Sodium Deoxycholate Market)

What is the current size and future outlook of the Sodium Deoxycholate Market?

• Answer: The Sodium Deoxycholate Market is projected to grow at a compound annual rate of XX% from to , transitioning from USD XX Billion in to USD XX billion by .

What is the present condition of the Sodium Deoxycholate market?

• Answer: As per the latest data, the Sodium Deoxycholate market is showing signs of growth, stability, and encountering certain challenges.

Who are the major players in the Sodium Deoxycholate market?

• Answer: Key players in the Sodium Deoxycholate market are notable companies recognized for their distinct characteristics or strengths.

What are the driving forces behind the growth of the Sodium Deoxycholate market?

• Answer: Growth in the Sodium Deoxycholate market is propelled by factors such as technological advancements, rising demand, and regulatory support.

What challenges are impacting the Sodium Deoxycholate market?

• Answer: Challenges facing the Sodium Deoxycholate market include competition, regulatory complexities, and economic factors.

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Table of Contents (Sodium Deoxycholate Market):

1. Introduction of the Sodium Deoxycholate Market

• Overview of the Market
• Scope of Report
• Assumptions

2. Executive Summary

3. Research Methodology of Market Research Intellect  

Link to chenlv

• Data Mining
• Validation
• Primary Interviews
• List of Data Sources

4. Sodium Deoxycholate Market Outlook

• Overview
• Market Dynamics
• Drivers
• Restraints
• Opportunities
• Porters Five Force Model
• Value Chain Analysis

5. Sodium Deoxycholate Market, By Product

6. Sodium Deoxycholate Market, By Application

7. Sodium Deoxycholate Market, By Geography

• North America
• Europe
• Asia Pacific
• Rest of the World

8. Sodium Deoxycholate Market Competitive Landscape

• Overview
• Company Market Ranking
• Key Development Strategies

9. Company Profiles

10. Appendix

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This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated.

All data generated or analyzed during this study are included in this published article and its supplementary information file. The 16S rDNA sequence of the isolates Citrobacter gillennii PMR001 and Klebsiella pneumoniae PMR001 has been deposited at GenBank under the accession numbers {"type":"entrez-nucleotide","attrs":{"text":"MN","term_id":"","term_text":"MN"}}MN and {"type":"entrez-nucleotide","attrs":{"text":"MN","term_id":"","term_text":"MN"}}MN , respectively.

Additional file 1: Figure S1. Structural formulae of nitrofurans and sodium deoxycholate. Figure S2. FZ interaction with DOC in growth inhibition of E. coli strain O157 and canine uropathogenic E. coli P50. Figure S3. Interactions of three nitrofurans (NIT, NFZ and CM4) with DOC in growth inhibition of Citrobacter gillenii PMR001. Figure S4. Interactions of three nitrofurans (NIT, NFZ and CM4) with DOC in growth inhibition of Salmonella enterica sv. Typhimurium LT2. Figure S5. Interactions of two nitrofurans (NIT and NFZ) with DOC in growth inhibition of Klebsiella pneumoniae PMR001.

This study is to our knowledge the first report of nitrofuran-deoxycholate synergy against Gram-negative bacteria, offering potential applications in antimicrobial therapeutics. The mechanism of DOC-FZ synergy involves FZ-mediated inhibition of TolC-associated efflux pumps that normally remove DOC from bacterial cells. One possible route contributing to that effect is via FZ-mediated nitric oxide production.

We further characterize the mechanism of synergy in E. coli K12, showing that disruption of the tolC or acrA genes that encode components of multidrug efflux pumps causes, respectively, a complete or partial loss, of the DOC-FZ synergy. This finding indicates the key role of TolC-associated efflux pumps in the DOC-FZ synergy. Overexpression of nitric oxide-detoxifying enzyme Hmp results in a three-fold increase in FICI for DOC-FZ interaction, suggesting a role of nitric oxide in the synergy. We further demonstrate that DOC-FZ synergy is largely independent of NfsA and NfsB, the two major activation enzymes of the nitrofuran prodrugs.

Using checkerboard assay, we show that combination of nitrofuran furazolidone (FZ) and DOC generates a profound synergistic effect on growth inhibition in several enterobacterial species including Escherichia coli, Salmonella enterica, Citrobacter gillenii and Klebsiella pneumoniae. The Fractional Inhibitory Concentration Index (FICI) for DOC-FZ synergy ranges from 0.125 to 0.35 that remains unchanged in an ampicillin-resistant E. coli strain containing a β-lactamase-producing plasmid. Findings from the time-kill assay further highlight the synergy with respect to bacterial killing in E. coli and Salmonella.

The 5-nitrofurans are an old class of synthetic antimicrobials, clinically introduced in the s and s [ 10 ]; several are commercially available, including furazolidone (FZ), nitrofurantoin (NIT) and nitrofurazone (NFZ) (Additional file 1 : Figure S1). FZ is used to treat bacterial diarrhea, giardiasis and as a component in combinatorial therapy for Helicobacter pylori infections; NIT and NFZ are used for urinary tract infections and topical applications, respectively [ 11 ]. They are prodrugs which require reductive activation, which is mediated in E. coli largely by two type-I oxygen-insensitive nitroreductases, NfsA and NfsB, and in their absence by type II oxygen-sensitive nitroreductase, AhpF [ 12 ]. NfsA and NfsB perform stepwise 2-electron reduction of the nitro moiety of the compound into two redox-reactive nitroso and hydroxylamino intermediates and biologically inactive amino-substituted product [ 13 , 14 ]. Detailed mechanism of how bacterial cells are killed by the reactive intermediate(s) is yet to be clarified. Nevertheless, it has been proposed that the hydroxylamino derivatives could trigger DNA lesions, disrupt protein structure and arrest RNA and protein biosynthesis [ 15 &#; 18 ]. Some reports also suggested that nitric oxide could be generated during the activation process, thus inhibiting the electron transport chain of bacterial cells although clear evidence for that is not available so far [ 19 , 20 ]. It is worth mentioning that nitroreductase-encoding genes are not only commonly present in enterobacteria but also found in other bacterial species such as Staphylococcus aureus, Bacillus subtilis, Vibrio fischeri and parasites (e.g. Trypanosoma brucei, Leishmania major) [ 21 &#; 24 ]. Nitroreductase enzymes play different physiological roles in different species; in E. coli, multiple functions have been proposed for NfsA and NfsB, including dihydropteridine reductase, chromate reductase, quinone-dependent azo reductase, and part of the oxidative stress response [ 21 ].

Sodium deoxycholate (DOC) (Additional file 1 : Figure S1e) is a facial amphipathic compound in bile, which is secreted into the duodenum to aid lipid digestion and confer some antimicrobial protection [ 4 ]. Though extensive research has been conducted to elucidate the interaction between DOC, either alone or in the bile mixture, and enteric bacteria, the mode of its antimicrobial action remains elusive. It was suggested that DOC could attack multiple cellular targets, including disturbing cell membranes, causing DNA damage, triggering oxidative stress and inducing protein misfolding [ 4 &#; 6 ]. Nonetheless, Gram-negative bacteria such as Escherichia coli and Salmonella are highly resistant to DOC by many mechanisms such as employment of diverse active efflux pumps, down-regulation of outer membrane porins and activation of various stress responses [ 5 , 7 &#; 9 ].

Antimicrobial resistance (AMR) is one of the most serious threats with which humans have been confronted. A UK-Prime-Minister-commissioned report in estimated that AMR, without appropriate interventions, will cause globally 10 million deaths per annum with a cumulative loss of US $100 trillion by [ 1 ]. In this dire context, alternative approaches are urgently needed besides the discovery of novel antibiotics. Antimicrobial combinations have been proven to be a promising approach with some widely accepted advantages, including enhancement of antimicrobial efficacy, deceleration of resistance development rate and alleviation of side effects by lowering the doses of two drugs [ 2 , 3 ]. Moreover, this approach could amplify the significance of ongoing antimicrobial discovery programs; particularly the advent of any novel antimicrobial compound would bring about a large number of possible double combinations with existing antimicrobial agents to be evaluated, let alone triple and quadruple combinations.

It has long been known that nitrofuran drugs need to be activated by nitroreductases NfsA and NfsB to exert its antibacterial activity [ 13 , 14 ]. As a result, the FZ activity and DOC-FZ synergy may depend on the activity of NfsA and NfsB enzymes. To investigate the role of these two enzymes in the DOC-FZ synergy, we examined the interaction between DOC and FZ in the ΔnfsA ΔnfsB E. coli strain lacking both of these enzymes. In agreement with the FZ activation role of NfsA/NfsB, disruption of these two genes led to an increase in the MIC causing 50% growth inhibition by a factor of 8 [ 12 ]. Nonetheless, the synergy between DOC and FZ still remained significant in the ΔnfsA ΔnfsB genetic background, with the FICI at 50% growth inhibition as low as 0. (Fig. ); this FICI value is only slightly higher than that of the wild type strain (0.25). We recently identified a third FZ-activating enzyme in E. coli, AhpF, which contributes to this prodrug activation in the ΔnfsA ΔnfsB genetic background [ 12 ]. Nevertheless, FZ was still effective against the ΔnfsA ΔnfsB ΔahpF mutant with the MIC 50% being 10-fold increased over the wild-type parent, suggesting the presence of additional 5-nitrofuran-activating enzymes in this organism and/or activation-independent mechanisms of action [ 12 ]. Here we analyzed the DOC-FZ synergy in the triple ΔnfsA ΔnfsB ΔahpF mutant and showed that the FICI value was close to that of the wild-type parent and double mutant (Fig. ). In other words, the contribution of NfsA/NfsB- and AhpF-mediated activation of FZ to the DOC-FZ synergy is very minimal. These findings indicate the role(s) of yet unexplored mechanisms of FZ action or activation in its interaction with DOC.

An intriguing question to be unraveled is how FZ could negatively influence the action of efflux pumps. We hypothesized that FZ could lower the energy supply to efflux pumps by mediating an increase in concentration of nitric oxide (NO). To verify the proposed model, the interaction between DOC and FZ in an E. coli strain with increased expression of protein Hmp (the E. coli nitric oxide dioxygenase) was inspected. The rationale for this is that overexpression of Hmp protein would increase detoxification of NO by conversion into benign NO 3 &#; ions, thus relieving the effect exerted by NO [ 26 ]. If NO was involved in the mechanism of the interaction between the two drugs, the synergy degree between them was expected to decrease with an increased abundance of Hmp proteins. In agreement with this hypothesis, overexpression of hmp was found to suppress the synergy between DOC and FZ by a factor of 3 (Fig. ). This finding supports a model that NO generated during FZ metabolism participates in the inhibition of electron transport chain [ 27 ], with the secondary effect of inhibiting the function of efflux pumps which are dependent on the electron transport chain for their activity.

To confirm that these observations were conferred by direct effect of the tolC and acrA deletion, rather than indirect effects of other genes or proteins, complementation of the corresponding deletion mutations by plasmid-encoded tolC and acrA was performed. To compensate for the multiple copies of plasmid-containing genes, complementation was carried out at a low level of expression, nevertheless it completely restored the strong synergy between DOC and FZ in these complemented strains (Fig. ). These findings collectively support the model that the efflux pumps act as the interacting point for the synergy between DOC and FZ.

To validate this model in E. coli, checkerboard assays were performed on the strains containing deletions of individual genes encoding the AcrAB-TolC efflux pump system, ΔtolC and ΔacrA. Deletion of tolC caused a shift from the synergistic interaction between DOC and FZ in the wild type (FICI = 0.125) to indifferent interaction (FICI = 0.75; Fig. a). The ΔacrA mutant exhibited a 3-fold increase in the FICI relative to the isogenic wild type strain. Such changes were also observed for the interaction between DOC and other nitrofurans, NIT, NFZ or CM4 (Fig. b, c and d).

One commonly accepted principle is that the synergy between two drugs is a consequence of one drug suppressing bacterial physiological pathways that mediate resistance to the other one. It has been reported that DOC could be expelled out of the cell via a wide range of efflux pumps, in which the tripartite efflux system AcrAB-TolC plays the major role [ 7 , 8 ]. This led us to hypothesize that FZ may inhibit the activity of efflux pumps, thus allowing intracellular accumulation of DOC to exert its lethal effect. If this scenario were true, disruption of the efflux pumps&#; function by mutation was expected to make this activity of FZ redundant, thus increasing the interaction index (FICI) in the mutant strains.

To investigate the interaction between DOC and FZ in terms of bactericidal effects, the time-kill assay was employed. Streptomycin-resistant E. coli K12 laboratory strain K and S. enterica serovar Typhimurium strain LT2 were exposed to sub-inhibitory concentrations of DOC ( μg/mL) alone, or FZ (0.5 × MIC) alone, or combination of the two drugs at such sub-inhibitory concentrations, over a 24 h period. The sample was taken at different time points and the surviving bacteria were titrated on the antimicrobial-free plates. Centrifugation and resuspension were applied for each sample to eliminate antimicrobial carryover before plating. After 24 h, the total cell count in the sample treated with the DOC-FZ combination was about five to six orders of magnitude lower than that in the sample treated with either DOC or FZ alone for both E. coli and Salmonella (Fig. ), demonstrating the synergy in bacterial killing between DOC and FZ.

We also examined the interaction between DOC and other nitrofuran compounds, including NIT, NFZ and CM4 (a 5-nitrofuran compound we discovered during an antimicrobial screening campaign against E. coli, Additional file 1 : Figure S1d) in all bacterial species mentioned above. We found that NIT, NFZ and CM4 were synergistic with DOC in E. coli laboratory strain (Fig. ), Citrobacter gillenii (Additional file 1 : Figure S3) and Salmonella enterica Typhimurium LT2 (Additional file 1 : Figure S4). By contrast, the interaction between NIT or NFZ and DOC was indifferent in K. pneumoniae isolate (Additional file 1 : Figure S5). CM4 did not inhibit growth of this Klebsiella strain in the range of concentrations used in the experiment (up to 256 μg/ml), hence the interaction could not be defined.

To evaluate the synergy between DOC and FZ, the checkerboard growth inhibition assays were performed for several enterobacteria, including Salmonella enterica subsp. enterica serovar Typhimurium LT2, Citrobacter gillenii, Klebsiella pneumoniae and two E. coli antibiotic-resistant laboratory strains (streptomycin-resistant and streptomycin/ampicillin-resistant). DOC and FZ act synergistically in inhibiting growth of the microorganisms listed (Fig. ), with FICI ranging from 0.125 in streptomycin-resistant E. coli strain (Fig. a) to 0.35 in K. pneumoniae (Fig. e). DOC-FZ synergy was also observed against two E. coli pathogenic strains (E. coli strain O157 and urinary tract infection strain P50; Additional file 1 : Figure S2). It is worth noting that, when used alone, very high DOC concentrations were required to exert an equivalent effect on inhibiting the growth of these Gram-negative enterobacteria, whereas the concentration in combination with FZ at the lowest FICI was within the range of the bile salts concentration in the human intestine (2.5 mg/mL or 6 mM) [ 25 ].

Discussion

Capitalization on drug combinations is one of the promising approaches to design novel therapies that will allow application of antimicrobials which have heretofore been ineffective against Gram-negative bacteria at concentrations that are acceptable for medical treatments. The synergistic interaction between DOC and FZ or other nitrofurans against a range of enterobacteria is of this kind. Decrease in growth inhibitory concentrations of nitrofurans when combined with DOC, demonstrated here, is desirable because the lowered concentration has a potential to remove the reported nitrofuran mutagenic and carcinogenic side-effects [15&#;18]. With respect to DOC and other bile salts, Gram-negative bacteria, such as E. coli and Salmonella enterica, have evolved high resistance to them using various mechanisms, such as multi-drug efflux pumps, a highly impermeable outer membrane, DNA damage repair machineries, the MqsR/MqsA toxin-antitoxin system and employment of multiple stress responses [9, 28&#;31]; inclusion of an active agent, such as FZ or other 5-nitrofurans, could reintroduce DOC in the battle against such formidable pathogens. These findings bring about two potential applications.

Firstly, DOC-nitrofuran combinations could be developed for topical applications, such as wound and burn dressings. In , ATX-101 in which deoxycholic acid is the active ingredient was approved by the Food and Drug Administrations for reduction of submental fat at a subcutaneous injection dose as high as 10&#;mg/mL and a volume of up to 10&#;mL [32]. This concentration is much higher than that of DOC (2.5&#;mg/mL) required for observing the synergy between DOC and nitrofurans, indicating that DOC concentrations of less than 10&#;mg/mL could be used in the combination without a concern about the serious toxicity. In addition to its antibacterial action, one could capitalize on the hydrogel-forming capability of DOC for transdermal drug delivery in DOC-nitrofuran combination. Such uses of DOC have been described in the rat model [33, 34]; no irritant effects on rat skins upon DOC-hydrogel application were observed in the histology studies [34].

Secondly, DOC and other bile salts are inherently present at 2&#;10&#;mM concentration range along the gastrointestinal tract, depending on nutritional state and microbiome composition [25, 35]. The efficacy of any drug used to treat intestinal infections would depend on the physicochemical properties of the local environment in which interaction with bile salts is one important factor. For instance, it has been reported that rifaximin, an RNA synthesis inhibitor, was more efficient in treating diarrhea-producing E. coli in the intestine than in the colon, due to the difference in the bile salt concentration [36]. We now provide evidence that FZ, an antibiotic prescribed for bacterial diarrhea [11, 37], acts synergistically with DOC in inhibiting the growth of enterobacteria, reducing the MIC of DOC from >&#;48&#;mM to 6&#;mM, the latter within the range of bile salt concentrations in the intestine. It is possible that the synergy in situ may contribute to the treatment. Co-administration of FZ and DOC provides a promising tool to treat bacterial diarrhea, especially for patients with conditions such as malnourishment or disorders in enterohepatic circulation and intestinal absorption, all of which may result in low levels of intestinal bile salts [4]. It should be noted that DOC alone does not represent the intestinal bile salts mixture and therefore application of DOC together with FZ may be necessary to enhance the synergy. LaRusso et al. [38] demonstrated that oral administration of DOC at 750&#;mg/day in healthy men did not result in any significant side effects even after 2&#;weeks of application, highlighting the possibility for oral uptake of DOC-FZ combination for bacterial diarrhea.

We have provided insights into the underlying mechanism of the synergy between DOC and FZ in their antibacterial action against E. coli as a model Gram-negative bacterium. We showed that disruption of tolC or acrA gene caused a considerable decrease in the synergy between DOC and FZ in the corresponding mutants. The TolC protein, whose removal disrupts the synergy more strikingly, appears to be the key determinant of synergy.

The observed difference in susceptibility to DOC/FZ combination between ΔtolC and ΔacrA mutants is in agreement with the fact that the TolC protein is shared by at least seven multidrug efflux pumps, while AcrA protein acts as the periplasmic connecting bridge for only two [39]. Thus, deletion of tolC gene is expected to give rise to a more pronounced effect on the loss of efflux activities than deletion of acrA gene.

Of great interest is how FZ could influence the activity of efflux pumps. The observed impairment of the DOC-FZ synergy by disruption of genes involved in multiple efflux pumps points to a common mechanism that could affect a wide range of efflux pumps simultaneously, such as proton motive force. It has been suggested that nitrofuran compounds during reductive activation might generate NO which subsequently inhibits the electron transport chain (ETC), diminishing the proton motive force across the cytoplasmic membrane [19, 20, 27] thereby de-energizing multiple efflux pumps and impairing the expulsion of toxic compounds. NO generation from nitrofurans in bacterial cells is, however, speculative, due to the detection limit of the used methods or rapid conversion of NO into other compounds [19, 20]. In the present work, we provide evidence for contribution of NO in the interaction between DOC and FZ via the observation that overexpression of NO-detoxifying enzyme Hmp decreased the synergistic interaction between the two agents. Since some DOC-FZ synergy was still retained after NO-detoxification, other mechanisms, including direct inhibition of the ETC by activated FZ, may be involved in the efflux pump inhibition. Further experiments are warranted to examine the effect of FZ on the electron transport chain via changes in the two components of the proton motive force using various probes (e.g. tetramethyl rhodamine methyl ester for membrane electric potential and pHluorin for ΔpH) or by monitoring cellular O2 uptake [40].

Notably, we showed that the DOC-FZ synergy does not depend on the presence of two major 5-nitrofuran-activating E. coli nitroreductases NfsA and NfsB and a minor activating enzyme AhpF. This finding raises interesting questions about activation and action of nitrofurans. The retention of synergy in the absence of NfsA, NfsB and AhpF implies that the inhibitory effect on the TolC-AcrAB efflux pump via NO is retained and, therefore, FZ likely undergoes reductive activation by alternative enzymes.