Niclosamide as a repurposing drug against Gram-positive bacterial infections

In vitro killing effect of berberine and niclosamide on ocular Demodex folliculorum

PURPOSE

To explore the in vitro killing effect of water-soluble berberine and lipid-soluble niclosamide against ocular Demodex folliculorum.

METHODS

Demodex with good vigor were collected from patients' eyelashes. These mites were randomly distributed into different groups with 20 mites in each group. Saline, Double Distilled Water (DDW), Polysorbate 80 (TWEEN 80), Polyethylene glycol 300 (PEG 300) and Castor Oil were used to screen solvents and cosolvents. 20 % Tea Tree Oil (TTO) and Anhydrous Ethanol (EtOH) were used as positive controls. 0.2 % Berberine, 0.25 % Niclosamide and 0.5 % Niclosamide, were designated as experimental groups. Following treatment, the analysis of Kaplan-Meier survival curves and survival time of mites and safety of drugs were then performed.

RESULTS

The survival of Demodex in vitro in Saline and DDW, was not significant different. Therefore, DDW, which was more conducive to the dissolution of berberine, was chosen as the solvent for berberine. 0.2 % Berberine significantly inhibited the survival distribution and survival time (P < 0.001) of Demodex in vitro compared with the DDW group. Through the evaluation of several cosolvents, PEG300 had milder effects on Demodex. Hence, the proportion of PEG300 in the niclosamide solvent group was increased to reduce the irritability of the vehicle. Furthermore, niclosamide could significantly inhibit the survival of Demodex compared with the vehicle group, and the effect of 0.5 % Niclosamide was more obvious (P < 0.001), and was better than 20 %TTO (P < 0.001). In addition, after niclosamide administration, Demodex bodies exhibited gradual distortion along with increased transparency and the presence of blurred dark particles compared to those in the vehicle group. Moreover, both drugs showed good subjective tolerability and safety in a mouse model.

CONCLUSION

0.2 % berberine and 0.5 % niclosamide effectively inhibited Demodex survival in vitro, with 0.5 % niclosamide superior to 20 % TTO. These two drugs, with anti-Demodex, anti-bacterial, and anti-inflammatory properties, may offer alternative treatment for Demodex blepharitis.

Antibacterial and Antibiofilm Activities of Hydralazine, an Antihypertensive Drug: In Vitro and In Silico Approaches

Background: The rise of multidrug-resistant (MDR) bacteria poses a significant challenge to global public health, contributing to increased morbidity and mortality rates. In this context, the repurposing of existing drugs has emerged as a promising strategy. In this study, hydralazine (HDZ), a vasodilator used as an antihypertensive since 1952, demonstrated antibacterial and antibiofilm activity against both Gram-positive and Gram-negative bacteria. Methods: In this study, the antibacterial activity of the antihypertensive hydralazine (HDZ) was evaluated against Gram-positive and Gram-negative strains through minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), growth curve with MIC and sub-MIC doses, combinatorial effect with gentamicin, scanning electron microscopy (SEM), molecular docking, and antibiofilm activity. Results: The MIC and MBC values ranged from 39.5 to 1.250 μg/mL, respectively. A change in the growth kinetics of the strains was observed when exposed to MIC and 1/2 MIC values, with a delay in the phases of up to 12 h. The combinatorial effect with gentamicin demonstrated an additive and indifferent potential when combined with HDZ. Conclusions: Furthermore, hydralazine showed antibiofilm activity against the tested strains, including MRSA. Electron microscopy analysis revealed significant changes in bacterial morphology when exposed to the MIC dose of HDZ for 4 h. The overall results of the study indicate hydralazine as a potential agent in the fight against bacterial infections.

Evaluation of Nano-Niclosamide in Killing Demodex folliculorum In Vitro and the Potential Application in Ocular Surface

Background/Objectives: Blepharitis is a condition often caused by Demodex folliculorum infestations, resulting in significant ocular discomfort and surface damage. Current treatments offer only temporary relief and fail to eliminate mites effectively. This study evaluates nano-niclosamide (nano-NCL), a lipophilic nanosuspension designed to enhance solubility and permeability, for targeting Demodex folliculorum. Methods: Nano-NCL was characterized by particle size, zeta potential, transmission electron microscopy, pH measurement, bacterial culture, and HPLC. Viable Demodex mites were collected from patients' eyelashes and assigned to six treatment groups: DDW, F127, 0.15% nano-NCL, 0.3% nano-NCL, 20% TTO, and Okra. Mite survival was analyzed using Kaplan-Meier curves. The ocular surface safety was assessed via slit-lamp examination, corneal fluorescein staining, and in vivo confocal microscopy. Results: The nano-NCL particles are uniformly rod-shaped, approximately 291 nm in size, and exhibit good stability, remaining suspended in various media for up to 20 days. The formulation has a stable pH of 6 and demonstrated no bacterial growth, indicating sterility and suitability for clinical use. In vitro, both 0.15% (w/v) and 0.30% (w/v) nano-NCL significantly reduced Demodex survival, with mortality rates ranging from 70.6% to 92.3% within 2 h. Safety evaluations showed minimal corneal staining and inflammation. Notably, 0.15% nano-NCL displayed efficacy comparable to that of 20% tea tree oil (TTO) and Okra, which are established anti-Demodex treatments. Conclusions: Nano-NCL, particularly at 0.15%, rapidly eliminates mites while maintaining excellent ocular tolerability, making it a promising treatment for Demodex-related ocular surface diseases.

Clinical safety and pharmacokinetics of a novel oral niclosamide formulation compared with marketed niclosamide chewing tablets in healthy volunteers: A three-part randomized, double-blind, placebo-controlled trial

AIM

Niclosamide is an established anthelmintic substance and a promising candidate for treating cancer, viral infections, and other diseases. However, its solubility in aqueous media is low, and the systemic bioavailability of the commercially available chewing tablet is poor, limiting the use of niclosamide for systemic treatment. A liquid oral formulation using polyethylene glycol 400 was developed and investigated in healthy volunteers to assess safety, tolerability, and pharmacokinetics in comparison to the marketed tablet. (ClinicalTrials.gov: NCT04644705).

METHODS

The study consisted of three parts: Part A was a double-blind placebo-controlled single ascending dose trial in three dose groups (200, 600, and 1600 mg) with four participants receiving either the investigational niclosamide formulation or placebo (3:1) under fasted and/or fed conditions. Part B was a crossover study comparing 1600 mg investigational niclosamide solution with the marketed 2000 mg chewing tablet in four healthy volunteers. Part C was a double-blind placebo-controlled multiple-dose trial comparing 1200 mg and 1600 mg (verum: placebo 4:2) in two dose groups with six subjects each, who received daily doses for seven days.

RESULTS

No serious or severe adverse events occurred. The most frequent adverse events were mild to moderate gastrointestinal reactions. There was also no apparent dependence between drug exposure levels (AUC, Cmax) and the severity and incidence of adverse events detectable. A relevant food effect was observed with a mean AUClast about 2-fold higher in fed condition compared to fasted condition. In Part B, dose-normalized Cmax and AUClast were similar for niclosamide solution and tablet. Absorption of niclosamide solution was highly variable. Some individuals showed high absorption (Cmax > 2µg/ml) whereas others did absorb only marginally. Importantly, there was no dose linearity in the range of 200 mg - 1600 mg. No signs of relevant systemic drug accumulation after multiple administrations were observed.

CONCLUSION

Overall safety and tolerability observed in healthy subjects were benign. This is also true for individuals with high absorption (Cmax > 2µg/ml), encouraging further research into niclosamide as a potential therapeutic agent. Galenic optimization, however, will remain challenging as evident from the observed exposure variability and non-linear PK. Non-linearity, if confirmed by additional data, might make niclosamide more suitable for multi-dose rather than high single dose regimens. The observed food effect should also be considered when further investigating systemic niclosamide exposures.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04644705.

Identification of pollutant markers in rural mountainous areas of China by combining non-targeted analysis with zebrafish embryo toxicity tests

Emerging pollutants (EPs) are increasingly found around the world, yet their composition and the risks pose to soil environments remain unclear, making a challenge to EP management, particularly in mountainous rural areas. In this study, we collected soils from three types of mountainous villages, each representing different levels of economic development: an industrial village, an ecotourism village, and an agricultural village. We analyzed these samples using non-target analysis and Danio rerio embryotoxicity test (ZET). A total of 216 compounds (level 2) were identified by matching with mzCloud database, with 149, 107, and 157 found in YY (industrial village), DX (ecotourism village) and LH (agricultural village), respectively. Interestingly, 78 compounds were present in all three villages, while the number of unique substances ranged from 7 to 47 in each village, serving as potential pollution markers. The most prevalent substances identified were aliphatics, heterocyclics, and aromatics. The ZET results showed that all soil extracts had significant acute toxic effects. Further analysis revealed a correlation between the toxic substances and the economic types of the villages. Specifically, linear chain dicarboxylic acids, drugs, and oxygenated polycyclic aromatic hydrocarbons (OPAHs) were the primary toxicants in the industrial village, whereas phthalate esters dominated in the other two villages. These findings provide valuable insights for effective monitoring of EPs in mountainous rural areas.

War and peace: exploring microbial defence systems as a source of new antimicrobial therapies

The WHO has compiled a list of pathogens that urgently require new antibiotics in response to the rising reports of antibiotic resistance and a diminished supply of new antibiotics. At the top of this list is fluoroquinolone-resistant Salmonella typhi, fluoroquinolone-resistant Shigella spp. and vancomycin-resistant Enterococcus faecium. Although these problems have been covered in great detail by other contemporary reviews, there are still some fundamental gaps in the translation of current knowledge of the infectious process and the molecular ecology of antibiotic production into a sustainable protocol for the treatment of pathogenic diseases. Therefore, in this narrative review we briefly discuss newly approved antimicrobial drugs (since 2014) that could help to alleviate the burden of multiresistant pathogens listed on the WHO priority list. Being conscious that such treatments may eventually run the risk of future cycles of resistance, we also discuss how new understandings in the molecular ecology of antibiotic production and the disease process can be harnessed to create a more sustainable solution for the treatment of pathogenic diseases.

Drug repurposing against antibiotic resistant bacterial pathogens

The growing prevalence of MDR and XDR bacterial pathogens is posing a critical threat to global health. Traditional antibiotic development paths have encountered significant challenges and are drying up thus necessitating innovative approaches. Drug repurposing, which involves identifying new therapeutic applications for existing drugs, offers a promising alternative to combat resistant pathogens. By leveraging pre-existing safety and efficacy data, drug repurposing accelerates the development of new antimicrobial therapy regimes. This review explores the potential of repurposing existing FDA approved drugs against the ESKAPE and other clinically relevant bacterial pathogens and delves into the identification of suitable drug candidates, their mechanisms of action, and the potential for combination therapies. It also describes clinical trials and patent protection of repurposed drugs, offering perspectives on this evolving realm of therapeutic interventions against drug resistance.

Drug Repurposing: Research Progress of Niclosamide and Its Derivatives on Antibacterial Activity

The development of antibiotic resistance complicates the treatment of infectious diseases and is a global public health threat. However, drug repurposing can address this resistance issue and reduce research and development costs. Niclosamide is a salicylanilide compound approved by the Food and Drug Administration (FDA), and it has been used clinically for treating parasitic infections for many years. Recent studies have shown that niclosamide can inhibit bacterial and fungus activity by affecting the quorum sensing system, biofilm formation, cell membrane potential, and other mechanisms. Here, we discuss recent advances in the antimicrobial applications of niclosamide and its derivatives to provide new perspectives in treating infectious diseases.

Sulfonamide Bioisosteres of Niclosamide Enhance Antibacterial Activity of Colistin and Bacitracin

Multicomponent therapy combining antibiotics with enhancer molecules known as adjuvants is an emerging strategy to combat antimicrobial resistance. Niclosamide is a clinically relevant anthelmintic drug with potential to be repurposed for its inherent antibacterial activity against Gram-positive bacteria and its ability to potentiate the antibacterial activity of colistin against susceptible and resistant Gram-negative bacteria. Herein, sulfonamide analogs of niclosamide were prepared and found to enhance colistin activity against Gram-negative bacteria. The ability of niclosamide and the new sulfonamide analogs to synergize with bacitracin against vancomycin-resistant Enterococcus faecium was also discovered.

Discovery of Salifungin as a Repurposed Antibiotic against Methicillin-Resistant Staphylococcus aureus with Limited Resistance Development

Exploring novel antimicrobial drugs and strategies has become essential to the fight MRSA-associated infections. Herein, we found that membrane-disrupted repurposed antibiotic salifungin had excellent bactericidal activity against MRSA, with limited development of drug resistance. Furthermore, adding salifungin effectively decreased the minimum inhibitory concentrations of clinical antibiotics against Staphylococcus aureus. Evaluations of the mechanism demonstrated that salifungin disrupted the level of H+ and K+ ions using hydrophilic and lipophilic groups to interact with bacterial membranes, causing the disruption of bacterial proton motive force followed by impacting on bacterial the function of the respiratory chain and adenosine 5'-triphosphate, thereby inhibiting phosphatidic acid biosynthesis. Moreover, salifungin also significantly inhibited the formation of bacterial biofilms and eliminated established bacterial biofilms by interfering with bacterial membrane potential and inhibiting biofilm-associated gene expression, which was even better than clinical antibiotics. Finally, salifungin exhibited efficacy comparable to or even better than that of vancomycin in the MRSA-infected animal models. In conclusion, these results indicate that salifungin can be a potential drug for treating MRSA-associated infections.

An overview to drug repurposing

Identification and implementation of novel drug are not only time consuming and expensive but also it poses huge challenge to reach into the market. Currently, thousands of USFDA approved drugs licence are being expired that can be repurposed for treating other diseases. Drug repurposing is an alternative solution to reduce time, cost and steps for development of drugs and their applications for treating disease. The current chapter emphases to brief the steps involved in drug discovery and drug repurposing. The chapter also includes repurposed drugs for treating bacterial, fungal and viral diseases. Unlocking the potential of already existed drug and repurposing them for other diseases that could accelerate drug discovery and aid in managing outbreaks.

Engineered Peptides Harboring Cation Motifs Against Multidrug-Resistant Bacteria

Multidrug-resistant (MDR) pathogens pose a serious threat to the health and life of humans, necessitating the development of new antimicrobial agents. Herein, we develop and characterize a panel of nine amino acid peptides with a cation end motif. Bioactivity analysis revealed that the short peptide containing "RWWWR" as a central motif harboring mirror structure "KXR" unit displayed not only high activity against MDR planktonic bacteria but also a clearance rate of 92.33% ± 0.58% against mature biofilm. Mechanically, the target peptide (KLR) killed pathogens by excessively accumulating reactive oxygen species and physically disrupting membranes, thereby enhancing its robustness for controlling drug resistance. In the animal model of sepsis infection by MDR bacteria, the peptide KLR exhibited strong therapeutic effects. Collectively, this study provided the dominant structure of short antimicrobial peptides (AMPs) to replenish our arsenals for combating bacterial infections and illustrated what could be harnessed as a new agent for fighting MDR bacteria.