Naftifine: a review

New insides into chimeric and hybrid azines derivatives with antifungal activity

During the last decades, five or six member rings azaheterocycles compounds appear to be an extremely valuable source of antifungal agents. Their use seems to be a very attractive solution in antifungal therapy and to overcome antifungal resistance in agriculture. The present review highlights the main results obtained in the field of hybrid and chimeric azine (especially pyridine, quinoline, phenanthroline, bypyridine, naphthyridine and their fused derivatives) derivatives presented in scientific literature from the last 10 years, with emphasis on antifungal activity of the mentioned compounds. A special attention was played to hybrid and chimeric azole-azine class, having in view the high antifungal potential of azoles.

Recent drug development and treatments for fungal infections

Fungal infections are now becoming a hazard to individuals which has paved the way for research to expand the therapeutic options available. Recent advances in drug design and compound screening have also increased the pace of the development of antifungal drugs. Although several novel potential molecules are reported, those discoveries have yet to be translated from bench to bedside. Polyenes, azoles, echinocandins, and flucytosine are among the few antifungal agents that are available for the treatment of fungal infections, but such conventional therapies show certain limitations like toxicity, drug interactions, and the development of resistance which limits the utility of existing antifungals, contributing to significant mortality and morbidity. This review article focuses on the existing therapies, the challenges associated with them, and the development of new therapies, including the ongoing and recent clinical trials, for the treatment of fungal infections. Advancements in antifungal treatment: a graphical overview of drug development, adverse effects, and future prospects.

Detection of Naganishia albida Yeasts in Dermatological Patients

The yeasts Cryptococcus albidus (Naganishia albida) usually occur on natural substrates and rarely are the etiological factor of different mycoses. More than a half of mycosis cases described in the literature were reported during the period from 2004 to 2021. In this regard, evaluation of yeast sensitivity to antimycotic drugs is as important as their identification. In the present study, two yeast isolates from the skin of female patients (age 7 and 74 years) with infective dermatitis (ICD-10-CM Code L30.3) were studied. Common identification of the isolates, MALDI-TOF mass spectrometry, and analysis of the nucleotide sequences of the ITS1-5.8S-ITS2 rDNA region showed that they belong to the species N. albida. The sensitivity of the obtained strains to antimycotics of three different chemical groups, namely itraconazole, naftifine, and amphotericin B, determined by microdilution method in a synthetic medium showed the following minimum inhibitory concentrations: 64-128, 16, and 0.125-4 μg/ml, respectively. It was found that the sensitivity of this yeast to pooled human serum was 30-47%, i.e. lower by 1.9-2.9 times than the sensitivity of the collection strains of C. albicans and C. neoformans. This result could be explained by lower prevalence of N. albida in the human population in comparison with these species. However, the sensitivity of N. albida strains to the low-molecular-weight fraction of serum was approximately the same as in C. albicans and C. neoformans, which indicates their high sensitivity to antimicrobial peptides.

Allylamines, Benzylamines, and Fungal Cell Permeability: A Review of Mechanistic Effects and Usefulness against Fungal Pathogens

Allylamines, naftifine and terbinafine, and the benzylamine, butenafine, are antifungal agents with activity on the fungal cell membrane. These synthetic compounds specifically inhibit squalene epoxidase, a key enzyme in fungal sterol biosynthesis. This results in a deficiency in ergosterol, a major fungal membrane sterol that regulates membrane fluidity, biogenesis, and functions, and whose damage results in increased membrane permeability and leakage of cellular components, ultimately leading to fungal cell death. With the fungal cell membrane being predominantly made up of lipids including sterols, these lipids have a vital role in the pathogenesis of fungal infections and the identification of improved therapies. This review will focus on the fungal cell membrane structure, activity of allylamines and benzylamines, and the mechanistic damage they cause to the membrane. Furthermore, pharmaceutical preparations and clinical uses of these drugs, mainly in dermatophyte infections, will be reviewed.

Styryl Group, a Friend or Foe in Medicinal Chemistry

The styryl (Ph-CH=CH-R) group is widely represented in medicinally important compounds, including drugs, clinical candidates, and molecular probes as it positively impacts the lipophilicity, oral absorption, and biological activity. The analysis of matched molecular pairs (styryl vs. phenethyl, phenyl, methyl, H) for the biological activity indicates the superiority aspect of styryl compounds. However, the Michael acceptor site in the styryl group makes it amenable to the nucleophilic attack by biological nucleophiles and transformation to the toxic metabolites. One of the downsides of styryl compounds is isomerization that impacts the molecular conformation and directly affects biological activity. The impact of cis-trans isomerism and isosteric replacements on biological activity is exemplified. We also discuss the styryl group-bearing drugs, clinical candidates, and fluorescent probes. Overall, the present review reveals the utility of the styryl group in medicinal chemistry and drug discovery.

Transdermal platform for the delivery of the antifungal drug naftifine hydrochloride based on porous vaterite particles

Development of a skin-targeted particulate delivery system providing an extended or sustained release of the payload and a localized therapeutic effect is one of the main challenges in the treatment of fungal skin infections. In the topical administration of antifungals, the drug should penetrate into the stratum corneum and lower layers of the skin in effective concentrations. Here, we introduce biodegradable calcium carbonate carriers containing 4.9% (w/w) of naftifine hydrochloride antimycotic allowing the efficient accumulation into the skin appendages. The proposed particulate formulation ensures the enhancement of the local drug concentration, prolongation of the payload release, and control over its rate. Furthermore, it provides a highly efficient cellular uptake and excellent bioavailability in vitro and enables a deep penetration during transfollicular delivery in vivo. The enhanced fungi growth inhibition efficiency of naftifine-loaded calcium carbonate carriers compared to naftifine solution makes them a promising alternative to creams and gels currently existing on the market.

Potential of Naftifine Application for Transungual Delivery

Naftifine is used to treat fungal skin infections as it inhibits dermatophytes, which are the cause of onychomycosis. However, naftifine's ability to permeate the human nail barrier has not been investigated, thus, the antimycotic potential is not clearly established. This work aims to evaluate the effect of penetration enhancing factors on the accumulation of naftifine hydrochloride through human nail clippings. Naftifine polymeric nail lacquers with Eudragit RL100 were developed as a suitable delivery system. Low penetration of naftifine into nail has been determined as less than 10% of applied drug dose accumulated in the nail layers. Incorporation of thioglycolic acid into formulations resulted in increased accumulation of antifungal agent in the nail layers by 100% compared with a control group. Salicylic acid did not effect naftifine accumulation in the human nail. The permeation of naftifine through the nail increased by threefold when the thioglycolic acid-containing formulation was applied and the nail was pretreated with a fractional CO2 laser. Structural changes of the nail barrier, induced by fractional CO2 laser, were visualized by microscopy. The results suggest, that naftifine nail penetration could be significantly increased when physical and chemical enhancing factors are applied.

Design and synthesis of 4-[4-formyl-3-(2-naphthyl)pyrazol-1-yl]benzoic acid derivatives as potent growth inhibitors of drug-resistant Staphylococcus aureus

We report the synthesis and antimicrobial studies of a new series of naphthyl-substituted pyrazole-derived hydrazones. Many of these novel compounds are potent growth inhibitors of several strains of drug-resistant bacteria. These potent compounds have inclined growth inhibitory properties for planktonic Staphylococcus aureus and Acinetobacter baumannii, and its drug-resistant variants with minimum inhibitory concentration (MIC) as low as 0.78 and 1.56 μg/mL respectively. These compounds also show potent activity against S. aureus and A. baumannii biofilm formation and eradication properties. Time Kill Assay shows that these compounds are bactericidal for S. aureus and bacteriostatic for A. baumannii. The probable mode of action is the disruption of the bacterial cell membrane. Furthermore, potent compounds are nontoxic to human cell lines at several fold higher concentrations than the MICs.

Visualisation of penetration of topical antifungal drug substances through mycosis-infected nails by matrix-assisted laser desorption ionisation mass spectrometry imaging

BACKGROUND

Matrix-assisted laser desorption ionisation mass spectrometry imaging (MALDI-MSI) is a mass spectrometry-based technique, which can be applied for compound-specific imaging of pharmaceuticals in tissues samples. MALDI-MSI technology is widely used to visualise penetration and distribution profile through different tissues but has never been used with nail tissue.

OBJECTIVES

This study used MALDI-MSI technology to visualise distribution profile and penetration into ex vivo human mycosis-infected toenails of three antifungal active ingredients amorolfine, ciclopirox and naftifine contained in topical onychomycosis nail treatment preparations, marketed as Loceryl^® , Ciclopoli^® and Exoderil^® .

METHODS

Three mycosis-infected toenails were used for each treatment condition. Six and twenty-four hours after one single topical application of antifungal drugs, excess of formulation was removed, nails were cryo-sectioned at a thickness of 20 μm, and MALDI matrix was deposited on each nail slice. Penetration and distribution profile of amorolfine, ciclopirox and naftifine in the nails were analysed by MALDI-MSI.

RESULTS

All antifungal actives have been visualised in the nail by MALDI-MSI. Ciclopirox and naftifine molecules showed a highly localised distribution in the uppermost layer of the nail plate. In comparison, amorolfine diffuses through the nail plate to the deep layers already 6 hours after application and keeps diffusing towards the lowest nail layers within 24 hours.

CONCLUSIONS

This study shows for the first-time distribution and penetration of certain antifungal actives into human nails using MALDI-MSI analysis. The results showed a more homogeneous distribution of amorolfine to nail and a better penetration through the infected nails than ciclopirox and naftifine.

In Vitro Skin Permeation and Antifungal Activity of Naftifine Microemulsions

Objectives

Microemulsions are fluid, isotropic, colloidal systems that have been widely studied as drug delivery systems. The percutaneous transport of active agents can be enhanced by their microemulsion formulation when compared to conventional formulations. The purpose of this study was to evaluate naftifine-loaded microemulsions with the objective of improving the skin permeation of the drug.

Materials and Methods

Microemulsions comprising oleic acid (oil phase), Kolliphor EL or Kolliphor RH40 (surfactant), Transcutol (co-surfactant), and water were prepared and physicochemical characterization was performed. In vitro skin permeation of naftifine from microemulsions was investigated and compared with that of its conventional commercial formulation. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to evaluate the interaction between the microemulsions and the stratum corneum lipids. Candida albicans American Type Culture Collection (ATCC) 10231 and Candida parapsilosis were used to evaluate the antifungal susceptibility of the naftifine-loaded microemulsions.

Results

The microemulsion formulation containing Kolliphor RH40 as co-surfactant increased naftifine permeation through pig skin significantly when compared with the commercial topical formulation (p<0.05). ATR-FTIR spectroscopy showed that microemulsions increased the fluidity of the stratum corneum lipid bilayers. Drug-loaded microemulsions possessed superior antifungal activity against Candida albicans ATCC 10231 and Candida parapsilosis.

Conclusion

This study demonstrated that microemulsions could be suggested as an alternative topical carrier with potential for enhanced skin delivery of naftifine.

Identifying and targeting cancer-specific metabolism with network-based drug target prediction

Background

Metabolic rewiring allows cancer cells to sustain high proliferation rates. Thus, targeting only the cancer-specific cellular metabolism will safeguard healthy tissues.

Methods

We developed the very efficient FASTCORMICS RNA-seq workflow (rFASTCORMICS) to build 10,005 high-resolution metabolic models from the TCGA dataset to capture metabolic rewiring strategies in cancer cells. Colorectal cancer (CRC) was used as a test case for a repurposing workflow based on rFASTCORMICS.

Findings

Alternative pathways that are not required for proliferation or survival tend to be shut down and, therefore, tumours display cancer-specific essential genes that are significantly enriched for known drug targets. We identified naftifine, ketoconazole, and mimosine as new potential CRC drugs, which were experimentally validated.

Interpretation

The here presented rFASTCORMICS workflow successfully reconstructs a metabolic model based on RNA-seq data and successfully predicted drug targets and drugs not yet indicted for colorectal cancer.

Fund

This study was supported by the University of Luxembourg (IRP grant scheme; R-AGR-0755-12), the Luxembourg National Research Fund (FNR PRIDE PRIDE15/10675146/CANBIO), the Fondation Cancer (Luxembourg), the European Union‘s Horizon2020 research and innovation programme under the Marie Sklodowska- Curie grant agreement No 642295 (MEL-PLEX), and the German Federal Ministry of Education and Research (BMBF) within the project MelanomSensitivity (BMBF/BM/7643621).

Niosome-loaded antifungal drugs as an effective nanocarrier system: A mini review

Skin is an important organ of the body due to offering an accessible and convenient site for drug administration. One of the disadvantages of transdermal drug delivery is the low penetration rate of drugs through the skin. Over the past decades, nanoparticles have been used as drug delivery systems to increase therapeutic effects or reduce toxicity. Encapsulation of drugs in nanoparticulate vesicles simplifies the transports of drugs into and across the skin.

Niosome nanoparticles are among these drug delivery systems, which have numerous applications in drug delivery and targeting. Niosomes are frequently used for loading drugs serving different purposes (e.g., anticancer, antiviral, and antibacterial agents). In recent years, there has been much research on the use of niosomal systems for the delivery of fungal drugs. A review of the literature investigating the advantages of niosomes in antifungal drug delivery can elucidate the efficiency and superiority of this nanocarrier over other nanocarriers.

Recent Status and Advancements in the Development of Antifungal Agents: Highlights on Plant and Marine Based Antifungals

The developing resistance in fungi has become a key challenge, which is being faced nowadays with the available antifungal agents in the market. Further search for novel compounds from different sources has been explored to meet this problem. The current review describes and highlights recent advancement in the antifungal drug aspects from plant and marine based sources. The current available antifungal agents act on specific targets on the fungal cell wall, like ergosterol synthesis, chitin biosynthesis, sphingolipid synthesis, glucan synthesis etc. We discuss some of the important anti-fungal agents like azole, polyene and allylamine classes that inhibit the ergosterol biosynthesis. Echinocandins inhibit β-1, 3 glucan synthesis in the fungal cell wall. The antifungals poloxins and nikkomycins inhibit fungal cell wall component chitin. Apart from these classes of drugs, several combinatorial therapies have been carried out to treat diseases due to fungal resistance. Recently, many antifungal agents derived from plant and marine sources showed potent activity. The renewed interest in plant and marine derived compounds for the fungal diseases created a new way to treat these resistant strains which are evident from the numerous literature publications in the recent years. Moreover, the compounds derived from both plant and marine sources showed promising results against fungal diseases. Altogether, this review article discusses the current antifungal agents and highlights the plant and marine based compounds as a potential promising antifungal agents.

Naphthalene, a versatile platform in medicinal chemistry: Sky-high perspective

Naphthalene, a cytotoxic moiety, is an extensively explored aromatic conjugated system with applications in various pathophysiological conditions viz. anticancer, antimicrobial, anti-inflammatory, antiviral, antitubercular, antihypertensive, antidiabetic, anti-neurodegenerative, antipsychotic, anticonvulsant, antidepressant. Naphthalene epoxides and naphthoquinones are most reactive metabolites of naphthalene and are responsible for the covalent interaction with cysteine amino acid of cellular proteins for cytotoxic nature. Many naphthalene derived bioactive phytoconstituents are present in nature including podophyllotoxins (Etoposide, teniposide), bis-ANS 82, Rifampicin, Justiprocumin A, B, Patentiflorin A. The naphthalene-based molecules, viz. Naphyrone, tolnaftate, naftifine, nafcillin, terbinafine, propranolol, nabumetone, nafimidone, naproxen, duloxetine, lasofoxifene, bedaquiline etc. have also been approved by FDA and are being marketed as therapeutics. Thus, the naphthalene scaffold emerges as an important building block in drug discovery owing to its broad spectrum of biological activities through varying structural modifications. This review incorporates the pharmacological aspects of different types of chemically modified naphthalene-based molecules along with their activity profile. This compiled information may serve as a benchmark for the alteration of existing ligands to design novel potent molecules with lesser side effects.

Reversible naftifine-induced carotenoid depigmentation in Rhodotorula mucilaginosa (A. Jörg.) F.C. Harrison causing onychomycosis

Rhodotorula mucilaginosa was isolated from a patient with onychomycosis, and identification was confirmed by morphological and cultural characteristics as well as by DNA molecular analysis. Antifungal agents naftifine (10 mg/mL, active substance in Exoderil) and bifonazole (10 mg/mL, active substance in Canespor) were tested in different concentrations to assess in vitro effects on fungal growth and carotenoid synthesis. The antifungal mechanisms of action of naftifine and bifonazole against R. mucilaginosa isolates were similar and affected the biosynthetic pathway of ergosterol. For the first time, this research demonstrates that naftifine affects the carotenoid biosynthetic pathway, producing depigmentation of R. mucilaginosa in solid and liquid media. Furthermore, depigmentation was a reversible process; naftifine-treated yeast cells that were depigmented resumed carotenoid production upon transfer to fresh media. Raman and UV-vis spectrophotometry in conjunction with chromatographic analysis detected changes in carotenoids in yeast cells, with torulene decreasing and B-carotene increasing after repigmentation. Transmission electron micrographs revealed critical ultrastructural modifications in the depigmented cells after naftifine treatment, i.e., a low-electron-density cell wall without visible mucilage or lamellate structure.

Colloidal nanocarriers for the enhanced cutaneous delivery of naftifine: characterization studies and in vitro and in vivo evaluations

In topical administration of antifungals, the drugs should pass the stratum corneum to reach lower layers of the skin in effective concentrations. Thus, the formulation of antifungal agents into a suitable delivery system is important for the topical treatment of fungal infections. Nanosized colloidal carriers have gained great interest during the recent years to serve as efficient promoters of drug penetration into the skin. Microemulsions are soft colloidal nanosized drug carriers, which are thermodynamically stable and isotropic systems. They have been extensively explored for the enhancement of skin delivery of drugs. This study was carried out to exploit the feasibility of colloidal carriers as to improve skin transport of naftifine, which is an allylamine antifungal drug. The microemulsions were formulated by construction of pseudoternary phase diagrams and composed of oleic acid (oil phase), Kolliphor^® EL or Kolliphor^® RH40 (surfactant), Transcutol^® (cosurfactant), and water (aqueous phase). The plain and drug-loaded microemulsions were characterized in terms of isotropy, particle size and size distribution, pH value, refractive index, viscosity, and conductivity. The in vitro skin uptake of naftifine from microemulsions was studied using tape stripping technique in pig skin. The drug penetrated significantly into stratum corneum from microemulsions compared to its marketed cream (P<0.05). Moreover, the microemulsion formulations led to highly significant amount of naftifine deposition in deeper layers of skin than that of commercial formulation (P<0.001). Microemulsion–skin interaction was confirmed by attenuated total reflectance – Fourier transformed infrared spectroscopy data, in vitro. The results of the in vivo tape stripping experiment showed similar trends as the in vitro skin penetration study. Topical application of the microemulsion on human forearms in vivo enhanced significantly the distribution and the amount of naftifine penetrated into the stratum corneum as compared to the marketed formulation (P<0.05). The relative safety of the microemulsion formulations was demonstrated with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide viability test. This study indicated that the nanosized colloidal carriers developed could be considered as an effective and safe topical delivery system for naftifine.

Small-molecule targeting of a diapophytoene desaturase inhibits S. aureus virulence

The surge of antibiotic resistance in Staphylococcus aureus has created a dire need for innovative anti-infective agents that attack new targets, to overcome resistance. In S. aureus, carotenoid pigment is an important virulence factor because it shields the bacterium from host oxidant killing. Here we show that naftifine, a US Food and Drug Administration (FDA)-approved antifungal drug, blocks biosynthesis of carotenoid pigment at nanomolar concentrations. This effect is mediated by competitive inhibition of S. aureus diapophytoene desaturase (CrtN), an essential enzyme for carotenoid pigment synthesis. We found that naftifine attenuated the virulence of a variety of clinical S. aureus isolates, including methicillin-resistant S. aureus (MRSA) strains, in mouse infection models. Specifically, we determined that naftifine is a lead compound for potent CrtN inhibitors. In sum, these findings reveal that naftifine could serve as a chemical probe to manipulate CrtN activity, providing proof of concept that CrtN is a druggable target against S. aureus infections.

Analysis of current antifungal agents and their targets within the Pneumocystis carinii genome

Pneumocystis pneumonia (PCP) remains a leading opportunistic infection in patients with weakened immune systems. The fungus causing the infection belongs to the genus, Pneumocystis, and its members are found in a large variety of mammals. Adaptation to the lung environment of a host with an intact immune system has been a key to its successful survival. Unfortunately, the metabolic strategies used by these fungi to grow and survive in this context are largely unknown. There were considerable impediments to standard approaches for investigation of this unique pathogen, the most problematic being the lack of a long term in vitro culture system. The absence of an ex vivo cultivation method remains today, and many fundamental scientific questions about the basic biology, metabolism, and life cycle of Pneumocystis are unanswered. Recent progress in sequencing of the Pneumocystis carinii genome, a species infecting rats, permitted a more informative search for genes and biological pathways within this pathogen that are known to be targets for existing antifungal agents. In this work, we review the classes of antifungal drugs with respect to their potential applicability to the treatment of PCP. Classes covered in the review are the azoles, polyenes, allylamines, and echinocandins. Factors limiting the use of standard antifungal treatments and the currently available alternatives (trimethoprim-sulfamethoxazole, atovaquone, and pentamidine) are discussed. A summary of genomic sequences within Pneumocystis carinii associated with the corresponding targeted biological pathways is provided. All sequences are available via the Pneumocystis Genome Project at http://pgp.cchmc.org/.

Candida infections and their prevention

Infections caused by Candida species have been increased dramatically worldwide due to the increase in immunocompromised patients. For the prevention and cure of candidiasis, several strategies have been adopted at clinical level. Candida infected patients are commonly treated with a variety of antifungal drugs such as fluconazole, amphotericin B, nystatin, and flucytosine. Moreover, early detection and speciation of the fungal agents will play a crucial role for administering appropriate drugs for antifungal therapy. Many modern technologies like MALDI-TOF-MS, real-time PCR, and DNA microarray are being applied for accurate and fast detection of the strains. However, during prolonged use of these drugs, many fungal pathogens become resistant and antifungal therapy suffers. In this regard, combination of two or more antifungal drugs is thought to be an alternative to counter the rising drug resistance. Also, many inhibitors of efflux pumps have been designed and tested in different models to effectively treat candidiasis. However, most of the synthetic drugs have side effects and biomedicines like antibodies and polysaccharide-peptide conjugates could be better alternatives and safe options to prevent and cure the diseases. Furthermore, availability of genome sequences of Candida   albicans and other non-albicans strains has made it feasible to analyze the genes for their roles in adherence, penetration, and establishment of diseases. Understanding the biology of Candida species by applying different modern and advanced technology will definitely help us in preventing and curing the diseases caused by fungal pathogens.