Direct interaction of antifungal azole-derivatives with calmodulin: a possible mechanism for their therapeutic activity

Cross-linkable star-hyperbranched unimolecular micelles for the enhancement of the anticancer activity of clotrimazole

Clotrimazole, a hydrophobic drug routinely used in the treatment of vaginal candidiasis, also shows antitumor activity. However, its use in chemotherapy has been unsuccessful to date due to its low solubility in aqueous media. In this work, new unimolecular micelles based on polyether star-hyperbranched carriers of clotrimazole are presented that can enhance solubility, and consequently the bioavailability, of clotrimazole in water. The amphiphilic constructs consisting of a hydrophobic poly(n-alkyl epoxide) core and hydrophilic corona of hyperbranched polyglycidol were synthesized in a three-step anionic ring-opening polymerization of epoxy monomers. The synthesis of such copolymers, however, was only possible by incorporating a linker to facilitate the elongation of the hydrophobic core with glycidol. Unimolecular micelles-clotrimazole formulations displayed significantly increased activity against human cervical cancer HeLa cells compared to the free drug, along with a weak effect on the viability of the normal dermal microvascular endothelium cells HMEC1. This selective activity of clotrimazole on cancer cells with little effect on normal cells was a result of the fact that clotrimazole targets the Warburg effect in cancer cells. Flow cytometric analysis revealed that the encapsulated clotrimazole significantly blocks the progression of the HeLa cycle in the G0/G1 phase and induces apoptosis. In addition, the ability of the synthesized amphiphilic constructs to form a dynamic hydrogel was demonstrated. Such a gel facilitates the delivery of drug-loaded single-molecule micelles to the affected area, where they can form a continuous, self-healing layer.

Potential Antifungal Targets for Aspergillus sp. from the Calcineurin and Heat Shock Protein Pathways

Aspergillus species, especially A. fumigatus, and to a lesser extent others (A. flavus, A. niger, A. terreus), although rarely pathogenic to healthy humans, can be very aggressive to immunocompromised patients (they are opportunistic pathogens). Although survival rates for such infections have improved in recent decades following the introduction of azole derivatives, they remain a clinical challenge. The fact that current antifungals act as fungistatic rather than fungicide, that they have limited safety, and that resistance is becoming increasingly common make the need for new, more effective, and safer therapies to become more acute. Over the last decades, knowledge about the molecular biology of A. fumigatus and other Aspergillus species, and particularly of calcineurin, Hsp90, and their signaling pathway proteins, has progressed remarkably. Although calcineurin has attracted much interest, its adverse effects, particularly its immunosuppressive effects, make it less attractive than it might at first appear. The situation is not very different for Hsp90. Other proteins from their signaling pathways, such as protein kinases phosphorylating the four SPRR serine residues, CrzA, rcnA, pmcA-pmcC (particularly pmcC), rfeF, BAR adapter protein(s), the phkB histidine kinase, sskB MAP kinase kinase, zfpA, htfA, ctfA, SwoH (nucleoside diphosphate kinase), CchA, MidA, FKBP12, the K27 lysine position from Hsp90, PkcA, MpkA, RlmA, brlA, abaA, wetA, other heat shock proteins (Hsp70, Hsp40, Hsp12) currently appear promising and deserve further investigation as potential targets for antifungal drug development.

High-throughput screening of TRPV1 ligands in the light of the Bioluminescence Resonance Energy Transfer technique

Ion channels are attractive drug targets for many therapeutic applications. However, high-throughput screening (HTS) of drug candidates is difficult and remains very expensive. We thus assessed the suitability of the Bioluminescence Resonance Energy Transfer (BRET) technique as a new HTS method for ion-channel studies by taking advantage of our recently characterized intra- and intermolecular BRET probes targeting the TRPV1 ion channel. These BRET probes monitor conformational changes during TRPV1 gating and subsequent coupling with Calmodulin, two molecular events that are intractable using reference techniques such as automated calcium assay (ACA) and automated patch-clamp (APC). We screened the small-sized Prestwick chemical library, encompassing 1200 compounds with high structural diversity, using either intra- and intermolecular BRET probes or ACA. Secondary screening of the detected hits was done using APC. Multiparametric analysis of our results shed light on the capability of calmodulin inhibitors included in the Prestwick library to inhibit TRPV1 activation by Capsaicin (CAPS). BRET was the lead technique for this identification process. Finally, we present data exemplifying the use of intramolecular BRET probes to study other TRPs and non-TRPs ion channels. Knowing the ease of use of BRET biosensors and the low cost of the BRET technique, these assays may advantageously be included for extending ion-channel drug screening. Significance Statement We screened a chemical library against TRPV1 ion channel using Bioluminescence Resonance Energy Transfer (BRET) molecular probes, and compared the results with the ones obtained using reference techniques such as automated calcium assay and automated patch-clamp. Multiparametric analysis of our results shed light on the capability of Calmodulin antagonists to inhibit chemical activation of TRPV1, and indicates that BRET probes may advantageously be included in ion channel drug screening campaigns.

Study the structure and thermal properties of carboxymethylated-β-cyclodextrin inclusion complex with bifonazole

Recently, many technological methods of enhancing the solubility and dissolution characteristics of poorly water soluble drugs have been reported in the literature. Сyclodextrins are able to form water-soluble non-covalent inclusion complexes with many poorly soluble lipophilic drugs. The purpose of this study is to evaluate the possibility of interaction of the antifungal drug Bifonazole (BFZ) through complexation with carboxymethylated-β-cyclodextrin (КМ-β-CD). Based on the data obtained, we can conclude that the presence of KM-β-CD improves solubilization of BFZ more than 50 times. Кеуwords: cyclodextrins, solubility, poorly-water soluble drugs, bifonazole.

Calmodulin inhibition as a mode of action of antifungal imidazole pharmaceuticals in non-target organisms

To improve assessment of risks associated with pharmaceutical contamination of the environment, it is crucial to understand effects and mode of action of drugs in non-target species. The evidence is accumulating that species with well-conserved drug targets are prone to be at risk when exposed to pharmaceuticals. An interesting group of pharmaceuticals released into the environment is imidazoles, antifungal agents with inhibition of ergosterol synthesis as a primary mode of action in fungi. However, imidazoles have also been identified as competitive antagonists of calmodulin (CaM), a calcium-binding protein with phylogenetically conserved structure and function. Therefore, imidazoles would act as CaM inhibitors in various organisms, including those with limited capacity to synthesize sterols, such as arthropods. We hypothesized that effects observed in crustaceans exposed to imidazoles are related to the CaM inhibition and CaM-dependent nitric oxide (NO) synthesis. To test this hypothesis, we measured (i) CaM levels and its gene expression, (ii) NO accumulation and (iii) gene expression of NO synthase (NOS1 and NOS2), in the cladoceran Daphnia magna exposed to miconazole, a model imidazole drug. Whereas significantly increased CaM gene expression and its cellular allocation were observed, supporting the hypothesized mode of action, no changes occurred in either NO synthase expression or NO levels in the exposed animals. These findings suggest that CaM inhibition by miconazole leads to protein overexpression that compensates for the loss in the protein activity, with no measurable downstream effects on NO pathways. The inhibition of CaM in D. magna may have implications for effect assessment of exposure to mixtures of imidazoles in aquatic non-target species.

Yeast caspase-dependent apoptosis in Saccharomyces cerevisiae BY4742 induced by antifungal and potential antitumor agent clotrimazole

Clotrimazole is an antifungal medication commonly used in the treatment of fungal infections. There is also promising research on using clotrimazole against other diseases such as malaria, beriberi, tineapedis and cancer. It was aimed to investigate the apoptotic phenotype in Saccharomyces cerevisiae induced by clotrimazole. The exposure of S. cerevisiae to 10 µM clotrimazole for 3, 6 and 9 h caused to decrease in cell viability by 24.82 ± 0.81, 56.00 ± 1.54 and 77.59 ± 0.53%, respectively. It was shown by Annexin V-PI assay that 110 µM clotrimazole treatment caused to death by 35.5 ± 2.48% apoptotic and only 13.1 ± 0.08% necrotic pathway within 30 min. The occurrence of DNA strand breaks and condensation could be visualised by the TUNEL and DAPI stainings, respectively. Yeast caspase activity was induced 12.34 ± 0.71-fold after 110 µM clotrimazole treatment for 30 min compared to the control. The dependency of clotrimazole-induced apoptosis to caspase was also shown using Δyca1 mutant.

Tumor-selective cytotoxicity of a novel pentadiene analogue on human leukemia/ lymphoma cells

BACKGROUND

A novel series of structurally divergent 1,5-diaryl-3-oxo-1,4-pentadiene analogues 1-10 displayed marked cytotoxic potencies towards a number of human leukemia/lymphoma cells.

OBJECTIVE

To identify novel selective cytotoxic compounds that induce apoptosis.

METHODS

The Differential Nuclear Staining (DNS) screening protocol was utilized to measure the cytotoxicity of all experimental dienones on several cancerous cells. Additionally, the selective cytotoxicity index was calculated by comparing the dienone's cytotoxicity between leukemia/lymphoma cells vs. non-cancerous cells. Furthermore, to discern whether a selected dienone induced cell death via apoptosis or necrosis on T-lymphocyte leukemia cells, diverse approaches were utilized to detect individual biochemical facets of apoptosis.

RESULTS

The dienones were tested for their anti-neoplastic efficiency on human leukemia/lymphoma-derived cell lines. Special emphasis was applied on dienone 1, on the basis of its sub-micromolar cytotoxicity (CC₅₀=0.43+0.02 μM) and high selective cytotoxicity index (11.1) exerted on T-leukemia cells. In general, dienone 1 showed the most potent cytotoxic properties as compared to other dienones and a related reference cytotoxin curcumin as well as the EF-24 curcumin analogue. Dienone 1 caused cell death by apoptosis in Jurkat cells as evidenced by inducing phosphatidylserine externalization, mitochondrial depolarization and caspase-3/7. These effects were mainly attributed to the induction of apoptotic pathways.

CONCLUSION

The novel dienone 1 was found to exhibit potent anti-leukemia activity by inducing programmed cell death/apoptosis. Consequently, dionone 1 should be developed further to examine its potential efficacy to combat malignancies in a pre-clinical animal model.

Are pharmaceuticals with evolutionary conserved molecular drug targets more potent to cause toxic effects in non-target organisms?

The ubiquitous use of pharmaceuticals has resulted in a continuous discharge into wastewater and pharmaceuticals and their metabolites are found in the environment. Due to their design towards specific drug targets, pharmaceuticals may be therapeutically active already at low environmental concentrations. Several human drug targets are evolutionary conserved in aquatic organisms, raising concerns about effects of these pharmaceuticals in non-target organisms. In this study, we hypothesized that the toxicity of a pharmaceutical towards a non-target invertebrate depends on the presence of the human drug target orthologs in this species. This was tested by assessing toxicity of pharmaceuticals with (miconazole and promethazine) and without (levonorgestrel) identified drug target orthologs in the cladoceran Daphnia magna. The toxicity was evaluated using general toxicity endpoints at individual (immobility, reproduction and development), biochemical (RNA and DNA content) and molecular (gene expression) levels. The results provide evidence for higher toxicity of miconazole and promethazine, i.e. the drugs with identified drug target orthologs. At the individual level, miconazole had the lowest effect concentrations for immobility and reproduction (0.3 and 0.022 mg L-1, respectively) followed by promethazine (1.6 and 0.18 mg L-1, respectively). At the biochemical level, individual RNA content was affected by miconazole and promethazine already at 0.0023 and 0.059 mg L-1, respectively. At the molecular level, gene expression for cuticle protein was significantly suppressed by exposure to both miconazole and promethazine; moreover, daphnids exposed to miconazole had significantly lower vitellogenin expression. Levonorgestrel did not have any effects on any endpoints in the concentrations tested. These results highlight the importance of considering drug target conservation in environmental risk assessments of pharmaceuticals.

Clotrimazole as a Cancer Drug: A Short Review

Although clotrimazole was first used against fungal infections, a body of research was later developed indicating that this drug has anticancer properties as well. The mechanism of action is based on the inhibition of mitochondrial-bound glycolytic enzymes and calmodulin, which starves cancer cells of energy. Clotrimazole and its derivatives have been shown to decrease rates of cancer cell proliferation, induce G1 phase arrest, and promote pro-apoptotic factors, which lead to cell death.

Analysis of the cytotoxic effects of ruthenium-ketoconazole and ruthenium-clotrimazole complexes on cancer cells

Ruthenium-based compounds have intriguing anti-cancer properties, and some of these novel compounds are currently in clinical trials. To continue the development of new metal-based drug combinations, we coupled ruthenium (Ru) with the azole compounds ketoconazole (KTZ) and clotrimazole (CTZ), which are well-known antifungal agents that also display anticancer properties. We report the activity of a series of 12 Ru-KTZ and Ru-CTZ compounds against three prostate tumor cell lines with different androgen sensitivity, as well as cervical cancer and lymphoblastic lymphoma cell lines. In addition, human cell lines were used to evaluate the toxicity against non-transformed cells and to establish selectivity indexes. Our results indicate that the combination of ruthenium and KTZ/CTZ in a single molecule results in complexes that are more cytotoxic than the individual components alone, displaying in some cases low micromolar CC50 values and high selectivity indexes. Additionally, all compounds are more cytotoxic against prostate cell lines with lower cytotoxicity against non-transformed epidermal cell lines. Some of the compounds were found to primarily induce cell death via apoptosis yet weakly interact with DNA. Our studies also demonstrate that the cytotoxicity induced by our Ru-based compounds is not directly related to their ability to interact with DNA.

The effect of clotrimazole on energy substrate uptake and carcinogenesis in intestinal epithelial cells

Clotrimazole has anticarcinogenic activity in several cell types. Our aims were to investigate the anticarcinogenic effect of clotrimazole in a tumoral intestinal epithelial (Caco-2) cell line, to compare it with the effect in a nontumoral intestinal epithelial cell line (IEC-6 cells), and to investigate inhibition of energy substrate uptake as a mechanism contributing to it. The effect of clotrimazole on cell proliferation, viability and differentiation, H-deoxyglucose (H-DG), H-O-methyl-glucose (H-OMG), and C-butyrate uptake, as well as mRNA expression levels of glucose transporters was assessed. In Caco-2 cells, clotrimazole decreased cellular viability and proliferation and increased cell differentiation. The effect on cell proliferation and viability was potentiated by rhodamine123. Clotrimazole also decreased cellular viability and proliferation in IEC-6 cells, but increased the cellular DNA synthesis rate and had no effect on cell differentiation. Exposure of Caco-2 cells to clotrimazole (10 µmol/l) for 1 and 7 days increased (by 20-30%) the uptake of H-DG and H-OMG, respectively, but had no effect on C-butyrate uptake. The effect on H-DG and H-OMG transport was maximal at 10 µmol/l, and the pharmacological characteristics of transport were not changed. However, clotrimazole changed the mRNA expression levels of the facilitative glucose transporter 2 and the Na-dependent glucose cotransporter. Clotrimazole exhibits comparable cytotoxic effects in tumoral and nontumoral intestinal epithelial cell lines. In Caco-2 cells, the cytotoxic effect of clotrimazole was strongly potentiated by the inhibition of oxidative phosphorylation. Moreover, stimulation of glucose uptake might be a compensation mechanism in response to the glycolysis inhibition caused by clotrimazole.

Cytotoxic copper(II), cobalt(II), zinc(II), and nickel(II) coordination compounds of clotrimazole

Sixteen novel mononuclear Cu(II), Co(II), Zn(II), and Ni(II) complexes of the biologically active ligand clotrimazole (clotri) of the forms [M(clotri)(2)Cl(2)]·nH(2)O (1-4), [M(clotri)(2)Br(2)]·nH(2)O (5-7), [M(clotri)(3)Br(2)] (8), [M(clotri)(3)NO(3)]NO(3)·nH(2)O (9, 11), [M(clotri)(3)(NO(3))(2)]·nH(2)O (10), and [M(clotri)(3)(OH(2))(2)NO(3)]NO(3)·nH(2)O (12) were synthesized and fully characterized. Dinuclear [Cu(2)(clotri)(4)μ(2)-Cl(4)]·2H(2)O (1a) and [Cu(2)(clotri)(4)μ(2)-Br(2)]·2H(2)O (5b) as well as tetranuclear [Cu(4)(clotri)(4)μ(4)-Br(6)μ(4)-O] (5a) complexes were also isolated. Complexes 1-7, 9, and 11 present a tetrahedral geometry; complex 8 exhibits a pentacoordinated structure; complexes 1a, 10 and 12 an octahedral geometry. X-ray crystal structures of [Cu(clotri)(2)Cl(2)](1), [Cu(clotri)(2)(EtOH)Cl(2)](1·EtOH), [Zn(clotri)(2)Cl(2)] (3), [Zn(clotri)(2)Br(2)] (7), and [Cu(4)(clotri)(4)μ(4)-Br(6)μ(4)-O] (5a) were obtained. Complexes 1-12 were tested for cytotoxic activity against the human carcinoma cell lines HeLa (cervix-uterine), PC3 (prostate), and HCT-15 (colon) displaying IC(50) values <30 μM. Confocal microscopy and nuclear dying (DAPI) for complex 1 showed condensation of cromatin and nuclear membrane fragmentation. Immunocytochemical detection/expression of biomarkers suggests that complexes 1 and 9 induce cell death via apoptosis. TUNEL assay detected DNA fragmentation in HeLa cells, resulting from apoptotic signaling cascades induced by Cu(II) complexes 1 and 9. (1)H NMR studies of the Zn(II) complexes showed that they can bind to nucleotides.

Miconazole induces fungistasis and increases killing of Candida albicans subjected to photodynamic therapy

Cutaneous and mucocutaneous Candida infections are considered to be important targets for antimicrobial photodynamic therapy (PDT). Clinical application of antimicrobial PDT will require strategies that enhance microbial killing while minimizing damage to host tissue. Increasing the sensitivity of infectious agents to PDT will help achieve this goal. Our previous studies demonstrated that raising the level of oxidative stress in Candida by interfering with fungal respiration increased the efficiency of PDT. Therefore, we sought to identify compounds in clinical use that would augment the oxidative stress caused by PDT by contributing to reactive oxygen species (ROS) formation themselves. Based on the ability of the antifungal miconazole to induce ROS in Candida, we tested several azole antifungals for their ability to augment PDT in vitro. Although miconazole and ketoconazole both stimulated ROS production in Candida albicans, only miconazole enhanced the killing of C. albicans and induced prolonged fungistasis in organisms that survived PDT using the porphyrin TMP-1363 and the phenothiazine methylene blue as photosensitizers. The data suggest that miconazole could be used to increase the efficacy of PDT against C. albicans, and its mechanism of action is likely to be multifactorial.

Mitochondrial metabolism inhibitors for cancer therapy

Cancer cells catabolise nutrients in a different way than healthy cells. Healthy cells mainly rely on oxidative phosphorylation, while cancer cells employ aerobic glycolysis. Glucose is the main nutrient catabolised by healthy cells, while cancer cells often depend on catabolism of both glucose and glutamine. A key organelle involved in this altered metabolism is mitochondria. Mitochondria coordinate the catabolism of glucose and glutamine across the cancer cell. Targeting mitochondrial metabolism in cancer cells has potential for the treatment of this disease. Perhaps the most promising target is the hexokinase-voltage dependent anion channel-adenine nucleotide translocase complex that spans the outer- and inner-mitochondrial membranes. This complex links glycolysis, oxidative phosphorylation and mitochondrial-mediated apoptosis in cancer cells. This review discusses cancer cell mitochondrial metabolism and the small molecule inhibitors of this metabolism that are in pre-clinical or clinical development.

Mechanism of the synergistic effect of amiodarone and fluconazole in Candida albicans

The antiarrhythmic drug amiodarone has been found to have fungicidal activity. In Saccharomyces cerevisiae, its antifungal activity is mediated by calcium overload stress, which leads to a rapid nuclear accumulation of the calcineurin-regulated transcription factor CRZ1. In addition, low doses of amiodarone have been reported to be synergistic with fluconazole in fluconazole-resistant Candida albicans. To establish its mechanism of toxicity in C. albicans, we used expression profiling of key pathway genes to examine cellular responses to amiodarone alone and in combination with fluconazole. Gene expression profiling of 59 genes was done in five C. albicans strains (three fluconazole-susceptible strains and two fluconazole-resistant strains) after amiodarone and/or fluconazole exposure. Of the 59 genes, 27 analyzed showed a significant change (>2-fold) in expression levels after amiodarone exposure. The up- or downregulated genes included genes involved in Ca(2+) homeostasis, cell wall synthesis, vacuolar/lysosomal transport, diverse pathway regulation, stress response, and pseudohyphal morphogenesis. As expected, fluconazole induces an increase in ergosterol pathway genes expression levels. The combination treatment significantly dampened the transcriptional response to either drug, suggesting that synergism was due to an inhibition of compensatory response pathways. This dampening resulted in a decrease in total ergosterol levels and decreased pseudohyphal formation, a finding consistent with decreased virulence in a murine candidiasis model.

Defining targets for investigating the pharmacogenomics of adverse drug reactions to antifungal agents

Adverse drug reactions (ADRs) associated with antifungal therapy are major problems in patients with invasive fungal infections. Whether by clinical history or patterns of genetic variation, the identification of patients at risk for ADRs should result in improved outcomes while minimizing deleterious side effects. A major contributing factor to ADRs with antifungal agents relates to drug distribution, metabolism and excretion. Genetic variation in key genes can alter the structure and expression of genes and gene products (e.g., proteins). Thus far, the effort has focused on identifying polymorphisms with either empirical or predicted in silico functional consequences; the best candidate genes encode phase I and II drug-metabolizing enzymes (e.g., CYP2C19 and N-acetyltransferase), plasma proteins (albumin and lipoproteins) and drug transporters (P-glycoprotein and multidrug resistance proteins), which can affect the disposition of antifungal agents, eventually leading to dose-dependent (type A) toxicity. Less is known regarding the key genes that interact with antifungal agents, resulting in idiosyncratic (type B) ADRs. The possible role of certain gene products and genetic polymorphisms in the toxicities of antifungal agents are discussed in this review. The preliminary data address the following: low-density lipoproteins and cholesteryl ester transfer protein in amphotericin B renal toxicity; toll-like receptor 1 and 2 in amphotericin B infusion-related ADRs; phosphodiesterase 6 in voriconazole visual adverse events; flavin-containing monooxygenase, glutathione transferases and multidrug resistance proteins 1 and 2 in ketoconazole and terbinafine hepatotoxicity; CYP enzymes and P-glycoprotein in drug interactions between azoles and coadministered medications; multidrug resistance proteins 8 and 9 on 5-flucytosine bone marrow toxicity; and mast cell activation in caspofungin histamine release. This will focus on high-priority candidate genes, which could provide a starting point for molecular studies to elucidate the potential mechanisms for understanding toxicity associated with antifungal drugs as well as identifying candidate genes for large population prospective genetic association studies.

Clotrimazole inhibits and modulates heterologous association of the key glycolytic enzyme 6-phosphofructo-1-kinase

Clotrimazole is an antifungal azole derivative recently recognized as a calmodulin antagonist with promising anticancer effects. This property has been correlated with the ability of the drug to decrease the viability of tumor cells by inhibiting their glycolytic flux and consequently decreasing the intracellular concentration of ATP. The effects of clotrimazole on cell glycolysis and ATP production are considered to be due to the detachment of the glycolytic enzymes from the cytoskeleton. Here, we show that clotrimazole directly inhibits the key glycolytic enzyme 6-phosphofructo-1-kinase (PFK). This property is independent of the anti-calmodulin activity of the drug, since it is not mimicked by the classical calmodulin antagonist compound 48/80. However, the clotrimazole-inhibited enzyme can be activated by calmodulin, even though calmodulin has no effect on PFK activity in the absence of the drug. Clotrimazole alone induces the dimerization of PFK reducing the population of tetramers, which is not observed when calmodulin is also present. Since PFK dimers are less active than PFK tetramers, this can explain the inhibitory effect of clotrimazole on the enzyme. Additionally, clotrimazole positively modulates the association of PFK with erythrocyte membranes. Altogether, our data support a hitherto unrecognized action of clotrimazole as a negative modulator of glycolytic flux through direct inhibition of the key enzyme PFK.

Clotrimazole decreases human breast cancer cells viability through alterations in cytoskeleton-associated glycolytic enzymes

Cancer cells are characterized by a high rate of glycolysis, which is their primary energy source. Glycolysis is known to be controlled by allosteric regulators, as well as by reversible binding of glycolytic enzymes to cytoskeleton. Clotrimazole is an anti-fungal azole derivative recently recognized as a calmodulin antagonist with promising anti-cancer effect. Here, we show that clotrimazole induced morphological and functional alterations on human breast cancer derived cell line, MCF-7. The drug decreased cell viability in a dose- and time-dependent manner, exhibiting an IC50 of 88.6+/-5.3 microM and a t0.5 of 89.7+/-7.2 min, with 50 microM clotrimazole. Morphological changes were evident as observed by scanning electron microscopy, which revealed the completely loss of protrusion responsible for cell adhesion after a 180 min of treatment with 50 microM clotrimazole. Giemsa stained cells observed by optical microscopy show morphological alterations and a marked nuclear condensation. These changes occurred in parallel to the detachment of the glycolytic enzymes, 6-phosphofructo-1-kinase and aldolase, from cytoskeleton. After a 45 min treatment with 50 microM clotrimazole, the remaining activities in a cytoskeleton enriched fraction was 16.4+/-3.6% and 41.0+/-15.6% of control for 6-phosphofructo-1-kinase and aldolase, respectively. Immunocytochemistry experiments revealed a decrease in the co-localization of 6-phosphofructo-1-kinase and F-actin after clotrimazole treatment, suggesting the site of detachment of the enzymes. Altogether, our results support evidence for apoptotic events that might be started by clotrimazole involving inhibition of glycolytic flux in MCF-7 cells and makes this drug a promising agent in the fight against human breast cancer.

Seborrhoeic dermatitis: current treatment practices

Seborrhoeic dermatitis (SD) is a recurrent, chronic inflammation of the skin that occurs on sebum rich areas such as the face, scalp and chest, characterised by red scaly lesions. The are many studies indicating that Malassezia yeasts play an important role in the aetiology of this condition, most of the evidence for which comes from demonstrated responsiveness to treatment with antifungal agents. Its aetiology, however, is far from being resolved. Some believe that it is the immune response of the skin to the Malassezia that is the cause of the disease. Traditional treatments of SD have been the use of keratolytic agents or corticosteroids. Since the discovery of ketoconazole, a considerable amount of research has been focused on determining the efficacy of various antifungal agents. This article reviews clinical trial data on treatment options available for SD.

Inhibition of TRPM2 channels by the antifungal agents clotrimazole and econazole

TRPM2 is a Ca(2+)-permeable non-selective cation channel that uniquely is activated by intracellular ADP-ribose. To date, only one pharmacological blocker of this channel, namely flufenamic acid (FFA), has been described. Here we demonstrate, using patch clamp electrophysiology, that the antifungal imidazoles clotrimazole and econazole inhibit ADP-ribose-activated currents in HEK-293 cells expressing recombinant human TRPM2 (hTRPM2). For both compounds, all concentrations in a range from 3 microM to 30 microM produced an essentially complete inhibition of the TRPM2-mediated current. The rate of current antagonism was dependent on the concentration applied, with higher concentrations producing faster block. In addition, decreasing extracellular pH accelerated inhibition of TRPM2 by both clotrimazole and econazole; extracellular alkalisation produced the converse effect. Additional experiments indicated hTRPM2 activation was required for the antagonism of either compound to develop, and that neither compound blocked from the intracellular face of the plasma membrane. ADP-ribose-activated whole-cell and single-channel currents in the rat insulinoma cell-line CRI-G1 were also antagonised by clotrimazole. Contrary to the observations made with hTRPM2, antagonism in CRI-G1 cells could be largely reversed following clotrimazole removal. These experiments suggest that imidazole antifungals may be useful tool antagonists for future studies of TRPM2 function.

Topical therapy for fungal infections

Fungi often infect the skin surface and subsequently invade the stratum corneum to avoid being shed from the skin surface by desquamation. Pharmacologic agents applied to the surface of the skin in the form of creams, lotions, or sprays, readily penetrate into the stratum corneum to kill the fungi (fungicidal agents), or at least render them unable to grow or divide (fungistatic agents). Thus, topical therapies work well to rid the skin of topical fungi and yeasts. Azole drugs such as miconazole, clotrimazole, and ketoconazole are fungistatic, limiting fungal growth but depending on epidermal turnover to shed the still-living fungus from the skin surface. Allylamines and benzylamines such as terbinafine, naftifine, and butenafine are fungicidal, actually killing the fungal organisms. Fungicidal drugs are often preferred over fungistatic drugs for treatment of dermatophytic fungal infections, since treatment times as short as one application daily for 1 week are associated with high cure rates. Furthermore, patients often stop treatments when the skin appears healed, usually after about a week of treatment. If this short-term treatment is stopped, fungi recur more often when fungistatic, rather than fungicidal, drugs have been used. Yeast infections such as those caused by Candida albicans respond less well to allylamine drugs. The azole drugs are often preferred for these types of infections. Nail infections are difficult to cure with topical therapies because the infections usually occur under the nail instead of on top of it and products penetrate poorly, if at all, through the nail plate. Infections of hair follicles, nails, and widespread infections often require systemic treatments. Antifungal agents are compounded into many different types of vehicles. Patients often prefer to treat weeping infections with spray formulations. Most physicians prescribe branded products in cream or lotion bases. Cost is a factor dictating prescription choice, especially since most products work well regardless of mechanism of action. Cost becomes especially important when infections involve large areas of the body surface. This article reviews various treatments of cutaneous fungal infections, with special emphasis on cure rates and rationales for choosing particular products.

Clotrimazole decreases glycolysis and the viability of lung carcinoma and colon adenocarcinoma cells

Glycolysis is known to be the primary energy source in most cancer cells. We investigated here the effect of clotrimazole (1-(alpha-2-chlorotrityl)imidazole), the antifungal azole derivative, which was recently recognized as calmodulin antagonist, on the levels of glucose 1,6-bisphosphate and fructose 1,6-bisphosphate, the two stimulatory signal molecules of glycolysis, and on ATP content and cell viability in LL/2 Lewis lung carcinoma cells and CT-26 colon adenocarcinoma cells. We found that clotrimazole induced a significant, dose- and time-dependent reduction in the levels of glucose 1,6-bisphosphate, fructose 1,6-bisphosphate, ATP, and cell viability. These findings suggest that clotrimazole causes a reduction in glycolysis and ATP levels, which eventually leads to cell destruction after 3 h of treatment. Since cell proliferation was also reported to be inhibited by calmodulin antagonists, this substance is most promising agent in treatment of cancer by inhibiting both cell proliferation and the glycolytic supply of ATP required for cancer cell growth.

Antifungal activity in Saccharomyces cerevisiae is modulated by calcium signalling

The most important group of antifungals is the azoles (e.g. miconazole), which act by inhibiting lanosterol demethylase in the sterol biosynthesis pathway. Azole activity can be modulated through structural changes in lanosterol demethylase, altered expression of its gene ERG11, alterations in other sterol biosynthesis enzymes or altered expression of multidrug transporters. We present evidence that azole activity versus Saccharomyces cerevisiae is also modulated by Ca2+-regulated signalling. (i) Azole activity was reduced by the addition of Ca2+. Conversely, azole activity was enhanced by the addition of Ca2+ chelator EGTA. (ii) Three structurally distinct inhibitors (fluphenazine, calmidazolium and a W-7 analogue) of the Ca2+-binding regulatory protein calmodulin enhanced azole activity. (iii) Two structurally distinct inhibitors (cyclosporin and FK506) of the Ca2+-calmodulin-regulated phosphatase calcineurin enhanced azole activity. (iv) Strains in which the Ca2+ binding sites of calmodulin were eliminated and strains in which the calcineurin subunit genes were disrupted demonstrated enhanced azole sensitivity; conversely, a mutant with constitutively activated calcineurin phosphatase demonstrated decreased azole sensitivity. (v) CRZ1/TCN1 encodes a transcription factor regulated by calcineurin phosphatase; its disruption enhanced azole sensitivity, whereas its overexpression decreased azole sensitivity. All the above treatments had comparable effects on the activity of terbinafine, an inhibitor of squalene epoxidase within the sterol biosynthesis pathway, but had little or no effect on the activity of drugs with unrelated targets. (vi) Treatment of S. cerevisiae with azole or terbinafine resulted in transcriptional upregulation of genes FKS2 and PMR1 known to be Ca2+ regulated. A model to explain the role of Ca2+-regulated signalling in azole/terbinafine tolerance is proposed.

Detachment of glycolytic enzymes from cytoskeleton of Lewis lung carcinoma and colon adenocarcinoma cells induced by clotrimazole and its correlation to cell viability and morphology

Cancer cells are characterized by a high rate of glycolysis, which is their primary energy source. Glycolysis is known to be controlled by allosteric regulators, as well as by reversible binding of glycolytic enzymes to cytoskeleton. We report here that clotrimazole (l-(alpha-2-chlorotrityl)imidazole), the antifungal azole derivative, which was recently recognized as calmodulin antagonist, induced a dose-dependent detachment of the glycolytic enzymes, phosphofructokinase (ATP: D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) and aldolase (D-fructose-l,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13), from cytoskeleton of LL/2 Lewis lung carcinoma cells and CT-26 colon adenocarcinoma cells. The detachment of glycolytic enzymes from cytoskeleton would reduce the provision of local ATP, in the vicinity of the cytoskeleton membrane, and would also affect cytoskeleton structure and cell shape. We show here that clotrimazole decreased the viability of LL/2 Lewis lung carcinoma cells and CT-26 colon adenocarcinoma cells. After 3h of incubation with clotrimazole, complete cell destruction was detected. Ultrastructural cell damage was manifested by disintegration of the outer membrane by scanning electron microscopy (SEM). The detachment of glycolytic enzymes from cytoskeleton, induced by clotrimazole, preceded the decrease in cell viability, which indicates that this is an early effect and not a result of cell death. Since the cytoskeleton is being recognized as an important modulator of cell function, proliferation, differentiation, and neoplasia, detachment of the glycolytic enzymes from cytoskeleton induced by clotrimazole, as well as its reported inhibitory action on cell proliferation, makes this drug the most promising agent in the treatment of cancer.

Anti-mycotics suppress interleukin-4 and interleukin-5 production in anti-CD3 plus anti-CD28-stimulated T cells from patients with atopic dermatitis

It is reported that anti-mycotic agents are effective for the treatment of patients with atopic dermatitis. We studied the in vitro effects of anti-mycotics on T helper-1 and T helper-2 cytokine production in anti-CD3 plus anti-CD28-stimulated T cells from atopic dermatitis patients and normal donors. The amounts of interleukin-4 and interleukin-5 secreted by anti-CD3/CD28-stimulated T cells were higher in atopic dermatitis patients than in normal donors. Azole derivatives, ketoconazole, itraconazole, miconazole, and nonazole terbinafine hydrochloride, and tolnaftate reduced interleukin-4 and interleukin-5 secretion without altering that of interferon-gamma and interleukin-2 in anti-CD3/CD28-stimulated T cells from both atopic dermatitis patients and normal donors. The azole derivatives were more inhibitory than nonazole anti-mycotics. These anti-mycotics reduced the anti-CD3/CD28-induced mRNA expression and promoter activities for interleukin-4 and interleukin-5. The 3',5'-cyclic adenosine monophosphate analog dibutyryl 3',5'-cyclic adenosine monophosphate reversed the inhibitory effects of the anti-mycotics on interleukin-4 and interleukin-5 secretion, mRNA expression, and promoter activities. Anti-CD3/CD28 transiently (< or = 5 min) increased intracellular 3',5'-cyclic adenosine monophosphate in T cells, and the increase was greater in atopic dermatitis patients than in normal donors. The increase of 3',5'-cyclic adenosine monophosphate by anti-CD3/CD28 correlated with interleukin-4 and interleukin-5 secretion by anti-CD3/CD28. The transient 3',5'-cyclic adenosine monophosphate increase was suppressed by anti-mycotics, and azole derivatives were more suppressive than nonazoles. Azole derivatives inhibited the activity of cyclic adenosine monophosphate-synthesizing adenylate cyclase whereas terbinafine hydrochloride and tolnaftate enhanced the activity of 3',5'-cyclic adenosine monophosphate-hydrolyzing cyclic nucleotide phosphodiesterase in atopic dermatitis and normal T cells. These results suggest that the anti-mycotics may suppress interleukin-4 and interleukin-5 production by reducing 3',5'-cyclic adenosine monophosphate signal, and stress their potential use for the suppression of T helper-2-mediated allergic reactions.

The ACVD task force on canine atopic dermatitis (XIX): general principles of therapy

The treatment of canine atopic dermatitis is multifaceted and consists of a combination of actions that include the use of allergen avoidance, anti-inflammatory agents, allergen-specific immunotherapy and antimicrobial drugs. The importance and order of these treatment steps vary from patient to patient. General recommendations for each of the therapeutic steps are highlighted in this paper. Specific details are covered in other papers of this issue.

Effects of Ca(2+)-ionophore A23187 and calmodulin antagonists on regulatory mechanisms of glycolysis and cell viability of NIH-3T3 fibroblasts

We studied here, in NIH-3T3 fibroblasts, the effect of the Ca(2+)-ionophore A23187 (which is known to increase intracellular-free Ca(2+)) on the control of glycolysis and cell viability and the action of calmodulin antagonists. Time-response studies with Ca(2+)-ionophore A23187 have revealed dual effects on the distribution of phosphofructokinase (PFK) (EC 2.7.1.11), the rate-limiting enzyme of glycolysis, between the cytoskeletal and cytosolic (soluble) fractions of the cell. A short incubation (maximal effect after 7 min) caused an increase in cytoskeleton-bound PFK with a corresponding decrease in soluble activity. This leads to an enhancement of cytoskeletal glycolysis. A longer incubation with Ca(2+)-ionophore caused a reduction in both cytoskeletal and cytosolic PFK and cell death. Both the "physiological" and "pathological" phases of the Ca(2+)-induced changes in the distribution of PFK were prevented by treatment with three structurally different calmodulin antagonists, thioridazine, an antipsychotic phenothiazine, clotrimazole, from the group of antifungal azole derivatives that were recently recognized as calmodulin antagonists, and CGS 9343B, a more selective inhibitor of calmodulin activity. The longer incubation with Ca(2+)-ionophore also induced a decrease in the levels of glucose 1,6-bisphosphate and fructose 1,6-bisphosphate, the two allosteric stimulatory signal molecules of glycolysis. All these pathological changes preceded the reduction in cell viability, and a strong correlation was found between the fall in ATP and cell death. All three calmodulin antagonists prevented the pathological reduction in the levels of the allosteric effectors, ATP and cell viability. These experiments may throw light on the mechanisms underlying the therapeutic action of calmodulin antagonists that we previously found in treatment of the proliferating melanoma cells, on the one hand, and skin injuries, on the other hand.

The antifungal agent butenafine manifests anti-inflammatory activity in vivo

BACKGROUND

Dermatophyte infections are often accompanied by a striking inflammatory reaction, alleviation of which has often been achieved by the concomitant but controversial use of topical steroidal agents. Recent investigations have suggested the presence of inherent anti-inflammatory properties associated with certain antifungal agents, particularly those within the allylamine class. Butenafine, the first and only approved representative of the benzylamine antifungals, possesses a chemical structure and antifungal activity similar to the allylamines. Although several studies have demonstrated excellent antimycotic efficacy, none has addressed anti-inflammatory properties associated with butenafine.

OBJECTIVE

This study was designed to determine whether butenafine, a benzylamine antifungal, expresses anti-inflammatory activity in vivo.

METHODS

A randomized single-blinded control investigation comparing the attenuation of UVB irradiation-induced erythema by butenafine, its proprietary base cream, and no application (negative control) was performed in humans.

RESULTS

Butenafine demonstrated a significant and marked decrease in UVB-induced erythema as compared with both the base cream and the unaltered control.

CONCLUSION

The benzylamine antifungal agent butenafine demonstrates inherent anti-inflammatory properties, in vivo, as demonstrated by reduced cutaneous erythema response after UVB irradiation.

Antifungal imidazoles block assembly of inducible NO synthase into an active dimer

Cytokine-inducible nitric oxide synthase (iNOS) is a homodimeric enzyme that generates nitric oxide (NO) and L-citrulline from L-arginine (L-Arg) and O2. The N-terminal oxygenase domain (amino acids 1-498; iNOSox) in each subunit binds heme, L-Arg, and tetrahydrobiopterin (H4B), is the site of NO synthesis, and is responsible for the dimeric interaction, which must occur to synthesize NO. In both cells and purified systems, iNOS dimer assembly is promoted by H4B, L-Arg, and L-Arg analogs. We examined the ability of imidazole and N-substituted imidazoles to promote or inhibit dimerization of heme-containing iNOSox monomers, or to affect iNOS dimerization in cells. Imidazole, 1-phenylimidazole, clotrimazole, and miconazole all bound to the iNOSox monomer heme iron. Imidazole and 1-phenylimidazole promoted iNOSox dimerization, whereas clotrimazole (30 microM) and miconazole (15 microM) did not, and instead inhibited dimerization normally promoted by L-Arg and H4B. Clotrimazole also bound to iNOSox dimers in the absence of L-Arg and H4B and caused their dissociation. When added to cells expressing iNOS, clotrimazole (50 microM) had no effect on iNOS protein expression but almost completely inhibited its dimerization and consequent NO synthesis over an 8-h culture period, without affecting calmodulin interaction with iNOS. Thus, imidazoles can promote or inhibit dimerization of iNOS both in vitro and in cells, depending on their structure. Bulky imidazoles like clotrimazole block NO synthesis by inhibiting assembly of the iNOS dimer, revealing a new means to control cellular NO synthesis.

Insulin stimulates binding of phosphofructokinase to cytoskeleton and increases glucose 1,6-bisphosphate levels in NIH-3T3 fibroblasts, which is prevented by calmodulin antagonists

We report here a novel mechanism of insulin action in cultures of NIH-3T3 fibroblasts. Our experiments revealed that in these cells, insulin induced a rapid and transient increase in cytoskeleton-bound phosphofructokinase (EC 2.7.1.11), the rate-limiting enzyme in glycolysis, with a corresponding decrease in soluble (cytosolic) activity. Insulin also induced a slower increase in the levels of glucose 1,6-bisphosphate, the potent activator of cytosolic glycolysis. Both the rapid and the slower stimulatory actions of insulin were prevented by treatment with structurally different calmodulin antagonists, which strongly suggest that calmodulin is involved in these effects of insulin. The present and our previous experiments in muscle suggest that rapid, Ca2+-calmodulin-mediated increase in the binding of glycolytic enzymes to cytoskeleton, as well as the slower increase in glucose 1,6-bisphosphate, may be a general mechanism, in different cells, in signal transduction of insulin.

Clotrimazole and bifonazole detach hexokinase from mitochondria of melanoma cells

Cancer cells are characterized by a high rate of glycolysis. Hexokinase (ATP: D-hexose 6-phosphotransferase, EC 2.7.1.1), the only glycolytic enzyme which binds to mitochondria, is exceptionally high in cancer cells, and believed to play a key role in regulating cell energy metabolism and cancer cell growth rate. We have previously found that clotrimazole (1-(alpha-2-chlorotrityl)imidazole) and bifonazole (1-(alpha-biphenyl-4-ylbenzyl)imidazole), the antifungal azole derivatives, which were recently recognized as calmodulin antagonists, are calmodulin antagonists which most effectively reduce glycolysis and ATP level in B16 melanoma cells. They act through allosteric regulation and detachment of glycolytic enzymes from cytoskeleton. Here we report of a novel, additional, mechanism of action of these drugs. We show that they induce a dose-dependent detachment of hexokinase from mitochondria of B16 melanoma cells. This effect preceded the decrease in cell viability. These results suggest that clotrimazole and bifonazole may be promising drugs in treatment of melanoma.

Detachment of glycolytic enzymes from cytoskeleton of melanoma cells induced by calmodulin antagonists

Glycolysis, which is the primary energy source in cancer cells, is known to be controlled by allosteric regulators, as well as by reversible binding of glycolytic enzymes to cytoskeleton. We have previously found that different calmodulin antagonists decrease the levels of allosteric activators of glycolysis, and reduce ATP content and cell viability in B16 melanoma cells. Here we report of a novel, additional, mechanism of action of calmodulin antagonists in melanoma cells. We show that these drugs cause a detachment of the glycolytic enzymes, phosphofructokinase (ATP: D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) and aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13), from cytoskeleton of B16 melanoma cells. This effect was dose- and time-dependent, and preceded the decrease in cell viability. The detachment of glycolytic enzymes from cytoskeleton would reduce the provision of local ATP, in the vicinity of the cytoskeleton-membrane and would affect cytoskeleton structure. Since the cytoskeleton is being recognized as an important modulator of cell function, proliferation, differentiation and neoplasia, detachment of the glycolytic enzymes from cytoskeleton induced by calmodulin antagonists, as well as their reported inhibitory action on cell proliferation, make these drugs most promising agents in treatment of cancer.

Serotonin decreases cytoskeletal and cytosolic glycolytic enzymes and the levels of ATP and glucose 1,6-bisphosphate in skin, which is prevented by the calmodulin antagonists thioridazine and clotrimazole

Serotonin (5-hydroxytryptamine) is believed to play a pathogenic role in skin damage and various skin abnormalities; however, its mechanism of action remains unknown. We show here that intradermal injection of serotonin in rats induced a marked reduction in the activities of the glycolytic enzymes, phosphofructokinase (EC 2.7.1.11) and aldolase (EC 4.1.2.13), in both the cytoskeletal and cytosolic fractions from skin. Serotonin also decreased the levels of glucose 1,6-bisphosphate in skin, the powerful regulator of glucose metabolism. These serotonin-induced changes were accompanied by a marked decrease in ATP content in skin. All these pathological changes induced by serotonin were prevented by treatment with two structurally different calmodulin antagonists: thioridazine, an antipsychotic phenothiazine, or clotrimazole, from the group of the antifungal azole derivatives that were recently recognized as calmodulin antagonists. The present results suggest that calmodulin antagonists may be effective drugs in the treatment of skin damage under various pathological conditions and diseases in which serotonin levels are increased.

Calmodulin antagonists decrease glucose 1,6-bisphosphate, fructose 1,6-bisphosphate, ATP and viability of melanoma cells

Glycolysis is known to be the primary energy source in cancer cells. We investigated here the effect of four different calmodulin antagonists: thioridazine (10-[2-(1-methyl-2-piperidyl) ethyl]-2-methylthiophenothiazine), CGS 9343B (1,3-dihydro-1-[1-[(4-methyl-4H,6H-pyrrolo[1,2-a] [4,1]-benzoxazepin-4-yl)methyl]-4-piperidinyl]-2 H-benzimidazol-2-one (1:1) maleate), clotrimazole (1-(alpha-2-chlorotrityl)imidazole) and bifonazole (1-(alpha-biphenyl-4-ylbenzyl)imidazole), on the levels of glucose 1,6-bisphosphate and fructose 1,6-bisphosphate, the two stimulatory signal molecules of glycolysis, and on ATP content and cell viability in B16 melanoma cells. We found that all four substances significantly reduced the levels of glucose 1,6-bisphosphate, fructose 1,6-bisphosphate and ATP, in a dose- and time-dependent manner. Cell viability was reduced in a close correlation with the fall in ATP. The decrease in glucose 1,6-bisphosphate and fructose 1,6-bisphosphate did not result from the cytotoxic effects of the calmodulin antagonists, since their content was already reduced before any cytotoxic effect was observed. These findings suggest that the fall in the levels of the two signal molecules of glycolysis, induced by the calmodulin antagonists, causes a reduction in glycolysis and ATP levels, which eventually leads to cell death. Since cell proliferation was also reported to be inhibited by calmodulin antagonists, these substances are most promising agents in treatment of cancer by inhibiting both cell proliferation and the glycolytic supply of ATP required for cell growth.

Effects of calmodulin antagonists and anesthetics on the skin lesions induced by 2-chloroethylethyl sulfide

The effects of calmodulin antagonists and anesthetics on the skin lesions induced by an alkylating vesicant, 2-chloroethylethyl sulfide, were investigated using female hairless mice. 2-Chloroethylethyl sulfide, topically applied (0.6 microliter/5 mm in diameter) on the back skin of hairless mice, induced mild to moderate petechiae on the 1st day, and ulcers with a thick scab after 3 days. The healing process started after 6 days, resulting in shedding of scabs on 9.52 days. Water-soluble ointment bases showed some beneficial effects, whereas oily bases made the skin lesions worse. Trifluoperazine (0.5-1%) and thioridazine (2%), potent calmodulin antagonists, in Pluronic F-127 base substantially prevented the development of 2-chloroethylethyl sulfide-induced skin lesions. A similar effect was achieved with pentamidine (10%), another type of calmodulin antagonist, but not with ketoconazole, a weak calmodulin antagonist. In addition, anesthetics, such as lidocaine and pentobarbital, showed some protection, although at high concentrations (> 5%). As judged by the microscopic appearance, trifluoperazine successfully reduced the hemorrhage and the infiltration of inflammatory cells in early skin lesions, and the formation of thick scabs, which leads to granulomatous scar tissue in late lesions. These results suggest that some calmodulin antagonists and anesthetics in water-soluble bases might be a choice for the treatment of 2-chloroethylethyl sulfide-induced skin burns.

Functional effects of econazole on inducible nitric oxide synthase: production of a calmodulin-dependent enzyme

1. We performed experiments to examine the effects of an anti-fungal imidazole compound, econazole, on the regulation and effects of lipopolysaccharide-inducible nitric oxide synthase (iNOS) activity in rat aortic rings and cultured J774 murine macrophage cells. 2. In endothelium-intact rings of thoracic aorta, phenylephrine caused a concentration-dependent contraction with EC50 of 1.9 +/- 0.15 x 10(-8) M (n = 5). Following incubation with lipopolysaccharide (LPS, 5 micrograms ml-1) for 8 h there was a right-shift in the concentration-response curve (EC50 3.1 +/- 0.28 x 10(-7) M, P < 0.05) with a depression in the maximum contraction from 1.44 +/- 0.25 g to 0.86 +/- 0.26 g (n = 4). Co-incubation of rings with econazole (1 x 10(-5) M) partially inhibited the LPS-induced loss of reactivity to phenylephrine (EC50 6.5 +/- 0.72 x 10(-8) M) and fully inhibited the reduction in maximum tension (1.49 +/- 0.19 g; n = 5). 3. In J774 cells, incubation with LPS (10 micrograms ml-1, 24 h) resulted in significant nitrite production that was inhibited by co-incubation with econazole (IC50 5.0 +/- 0.9 x 10(-6) M; n = 5). In cells stimulated with LPS, production of L-[3H]-citrulline from L-[3H]-arginine was 6.41 +/- 0.22 pmol mg-1 protein min-1 (n = 3). This was inhibited by 92 +/- 6% by addition of NG-monomethyl-L-arginine (L-NMMA, 1 x 10(-3) M; n = 3) to the homogenate but not by econazole (1 x 10(-5) M; n = 3). In contrast pretreatment of cells with econazole (1 x 10(-5) M) markedly reduced the LPS-induced [3H]-citrulline production (0.86 +/- 0.053 pmol mg-1 protein min-1; P < 0.01; n = 3). 4. In cells treated with LPS and econazole, L-[3H]-citrulline production was restored in a concentration-dependent manner by addition of calmodulin (1 x 10(-8)-3 x 10(-7) M) with an IC50 of 4.2 +/- 0.9 x 10(-8) M. 5. We have shown that econazole inhibits the functional and biochemical activity of iNOS in rat aortic rings and cultured J774 cells. Treatment of cells with econazole renders the NO synthase functionally inactive. In econazole-treated cells enzyme activity is restored by calmodulin suggesting that econazole may inhibit the binding of this essential co-factor to the enzyme following its production. These studies may have implications for the design of novel anti-inflammatory agents working through the L-arginine-nitric oxide pathway.

Potent antagonism of calmodulin activity in vitro, but lack of antiproliferative effects on keratinocytes by the novel leukotriene biosynthesis inhibitor MK-886

MK-886, a leukotriene biosynthesis inhibitor, which prevents the translocation and activation of 5-lipoxygenase, has been proposed as an effective drug for the treatment of inflammatory disorders, including psoriasis. In the present study, we investigated the effects of MK-886 on calmodulin as a potential target protein of anti-inflammatory drug activity, and on the proliferation of cultured human keratinocytes, a calmodulin-dependent cellular response with indicative value for antipsoriatic drug activity. Despite potent calmodulin-antagonistic activity in vitro, MK-886 failed to block cell proliferation in a human keratinocyte line, whereas trifluoperazine, a well characterized calmodulin antagonist with similar effects on calmodulin activity in our in vitro assays, inhibited cell proliferation in a dose-dependent manner. Further investigations on the mechanism of action revealed that, in contrast with trifluoperazine, calmodulin antagonism by MK-886 in vitro is likely to be mediated at the level of the allosteric calmodulin-recognition site of phosphodiesterase, rather than by binding to calmodulin itself. Therefore, our data do not conflict with the proposed role of calmodulin in the regulation of cell proliferation, but demonstrate that drug-induced antagonism of calmodulin, detected by inhibition of calmodulin-dependent enzymes in vitro, is not necessarily linked to antiproliferative activity in human keratinocytes.

Anti-inflammatory actions of benzoyl peroxide: effects on the generation of reactive oxygen species by leucocytes and the activity of protein kinase C and calmodulin

For many years, benzoyl peroxide has been used as a topical treatment for acne. Although the drug has been shown to interfere with a variety of pathways, believed to be of importance in the aetiopathogenesis of acne, its mechanism of action is thought to be principally antibacterial. Recent circumstantial evidence suggests that protein kinase C might serve as an additional pharmacological target of benzoyl peroxide. In the present study, we investigated the effects of benzoyl peroxide on the release of reactive oxygen species, regulated by protein kinase C and calmodulin, from human neutrophils, a potentially important step in acne inflammation. Micromolar drug concentrations were found to inhibit the release of reactive oxygen species, but there was marked drug-induced cytotoxicity in neutrophils. However, when tested in cell-free assays, benzoyl peroxide displayed marginal inhibition of protein kinase C, but failed to antagonize calmodulin. Further investigations on its mechanism of action revealed non-specific interference with nucleotide binding sites. Therefore, the data presented here indicate that, in contrast with our previous findings with tetracycline derivatives, the clinical anti-inflammatory activity of benzoyl peroxide is unlikely to be mediated by protein kinase C or calmodulin. The differential interaction of drugs with protein kinase C and calmodulin might help to explain their different clinical usefulness in various degrees of acne severity.

Effect of anti-fungal imidazoles on mRNA levels and enzyme activity of inducible nitric oxide synthase

1. Experiments were performed to examine the effects of anti-fungal imidazole compounds (clotrimazole, econazole and miconazole) on the induction of nitric oxide (NO) synthase and subsequent production of NO in the cultured murine monocyte/macrophage cell line J774 using a specific cDNA probe for inducible NO synthase mRNA and by monitoring nitrite production. 2. Stimulation of J774 cells with lipopolysaccharide (LPS, 10 micrograms ml-1) resulted in the induction of NO synthase activity as determined by nitrite accumulation in the culture medium (48 +/- 3 nmol per 10(6) cells over 24 h). Production of nitrite was inhibited by co-incubation of cells with LPS (10 micrograms ml-1) and either dexamethasone (10 microM) or NG-monomethyl-L-arginine (L-NMMA; 0.1 mM), however, only L-NMMA was an effective inhibitor of nitrite production when added after induction of NO synthase had occurred. 3. Co-incubation of J774 cells with LPS (10 micrograms ml-1) and either clotrimazole, econazole or miconazole (1-10 microM) resulted in a concentration-dependent inhibition of nitrite production over the subsequent 24 h without any evidence for a cytotoxic effect. However, addition of these imidazoles after induction of NO synthase did not inhibit nitrite production. 4. Messenger RNA for inducible NO synthase was not detected in unstimulated J774 cells. Treatment with LPS (10 micrograms ml-1) for 4 h resulted in significant expression of mRNA for inducible NO synthase which was not altered in the presence of econazole (10 microM) but was reduced significantly by dexamethasone (10 microM). 5. These results demonstrate that anti-fungal imidazoles inhibit the production of nitric oxide by cultured J774 cells by a mechanism which appears to differ from that of dexamethasone and substrate type inhibitors of NO synthase. Furthermore, the presence of mRNA for NO synthase does not indicate the presence of functionally active NO synthase.