Rapid Fungicidal Activity Research Articles

Natural phytoalexins inspired the discovery of new biphenyls as potent antifungal agents for treatment of invasive fungal infections

With the aim of discovering novel and effective antifungal agents derived from natural sources, a series of new biphenyls based on natural biphenyl phytoalexins were designed, synthesized and evaluated for their antifungal activities against four invasive fungi. By modifying the two benzene rings of noraucuparin, a well-known biphenyl phytoantitoxin, some promising compounds with remarkable antifungal activity were discovered. Notably, compounds 23a, 23e and 23h exhibited potent activities and a broad antifungal spectrum with low MICs of 0.25–16 μg/mL, which were 8−256-fold more potent than that of the lead compound noraucuparin. Particularly, they displayed comparable potency to the positive control amphotericin B against Cryptococcus neoformans. Some interesting structure-activity relationships have also been discussed. Preliminary mechanism studies revealed that compound 23h might achieve its rapid fungicidal activity by disrupting the fungal cell membrane. Moreover, compound 23h exhibited significant inhibition against some virulence factors of Cryptococcus neoformans, low toxicity to normal human cells, as well as favorable pharmacokinetic and drug-like properties. The above results evidenced that the development of new antifungal candidates derived from natural phytoalexins was a bright and promising strategy.

Novel antimicrobial peptide DvAMP serves as a promising antifungal agent against Cryptococcus neoformans

Cryptococcus neoformans is an important opportunistic human fungal pathogen that causes cryptococcosis in immunocompromised patients. However, the number of drugs for the treatment of cryptococcosis is restricted, and the development of novel antifungal drugs and innovative strategies for the treatment of cryptococcosis is urgently needed. In this study, we validated that DvAMP is a novel antimicrobial peptide with antimicrobial activity and that it was obtained by pre-screening from the UniProt database of more than three million unknown functional sequences based on the quantitative structure–activity relationships (QSARs) protocol (http://www.chemoinfolab.com/antifungal). The peptide exhibited satisfactory biosafety and physicochemical properties, and relatively rapid fungicidal activity against C. neoformans. Meanwhile, DvAMP was able to inhibit the static biofilm of C. neoformans and cause a reduction in the thickness of the capsule. In addition, DvAMP exerts antifungal effects through membrane-mediated mechanisms (membrane permeability and depolarization) and mitochondrial dysfunction, involving a hybrid multi-hit mechanism. Furthermore, by using the C. neoformans-Galleria mellonella infection model, we demonstrated that DvAMP has significant therapeutic effects in vivo and that it significantly reduces the mortality and fungal burden of infected larvae. These results suggest that DvAMP may be a potential antifungal drug candidate for the treatment of cryptococcosis.

Antifungal Properties of Hydrazine-Based Compounds against Candida albicans.

Candida albicans, an opportunistic yeast, is the most common cause of fungal infection. In the past decade, there has been an increase in C. albicans resistance to existing antifungal drugs, which has necessitated the development of new antifungal agents. In the present study, screening 60 compounds from the JUNIA chemical library enabled us to explore an additional 11 hybrid compounds that contain pyrrolidinone rings and hydrazine moieties for their potential antifungal activities. This chemical series was identified with fair to excellent antifungal activities. Among this series, three molecules (Hyd.H, Hyd.OCH3, and Hyd.Cl) significantly reduced C. albicans viability, with rapid fungicidal activity. In addition, these three compounds exhibited significant antifungal activity against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. Hyd.H, Hyd.OCH3, and Hyd.Cl did not show any cytotoxicity against human cancer cell lines up to a concentration of 50 µg/mL and decreased Candida biofilm formation, with a significant reduction of 60% biofilm formation with Hyd.OCH3. In an infection model of Caenorhabditis elegans with C. albicans, hydrazine-based compounds significantly reduced nematode mortality. Overall, fungicidal activity was observed for Hyd.H, Hyd.OCH3, and Hyd.Cl against C. albicans, and these compounds protected C. elegans from C. albicans infection.

GR-2397: Review of the Novel Siderophore-like Antifungal Agent for the Treatment of Invasive Aspergillosis.

GR-2397 (previously VL-2397, ASP2397) is a first-in-class antifungal agent for the treatment of invasive aspergillosis. This siderophore-like molecule resembles ferrichrome; however, it is differentiated by three amino acid changes and an aluminum rather than iron chelate. GR-2397 is transported into fungal cells via the Sit1 transporter, which is not found in humans, leading to fungal specificity. Although the precise mechanism of action is currently unknown, GR-2397 is active against Aspergillus spp. including azole-resistant strains, Fusarium solani, and Candida glabrata in addition to other organisms. Efficacy has been demonstrated in several animal models of invasive aspergillosis, including a 24 h delayed-treatment model where rapid fungicidal activity was observed. Phase 1 single- and multiple-ascending intravenous dose studies showed that GR-2397 was safe and well-tolerated in humans. No signs of GR-2397 accumulation were observed following IV infusions of 300, 600, and 1200 mg every 24 h (q24h) for 7 days. The favorable safety, tolerability and drug–drug interaction profile, along with good tissue distribution, support further development of GR-2397 as a new treatment option for patients with invasive aspergillosis. This systematic review summarizes the published findings of GR-2397.

Comparative Fungicidal Activities of N-Chlorotaurine and Conventional Antiseptics against Candida spp. Isolated from Vulvovaginal Candidiasis.

N-chlorotaurine (NCT), the N-chloro derivative of the amino acid taurine, is a long-lived oxidant produced by stimulated human leucocytes. NCT has antimicrobial activities which are generally enhanced in the presence of organic material. The aim of this study was to investigate fungicidal effects of NCT and conventional antiseptics against Candida isolated from vulvovaginal candidiasis (VVC). Chlorhexidine (CHX, 1.6%), octenidine dihydrochloride (OCT, 0.08%), povidone iodine (PVP-I, 8%), boric acid (8%), and NCT (0.1% (5.5 mM)) were evaluated against forty-four Candida isolates, according to European Standard methods, at 30, 60, 90, and 120 min and 24 h in the presence of skim milk as an organic material. CHX, OCT, and PVP-I showed rapid fungicidal activity against all Candida isolates with 5–6 log10 reduction of viable counts after 30 min, whereas boric acid and NCT needed 1 h against Candida albicans and 2 h against non-albicans Candida for a significant 3 log10 reduction. NCT showed fungicidal activity (defined as ≥4 log10 reduction) against C. albicans within 90 min and C. non–albicans within 24 h. Based upon all presently available data, including our results, NCT could be used as a new agent for treatment of local fungal infections such as VVC.

Antifungal activity of [K3]temporin-SHa against medically relevant yeasts and moulds.

Few antifungal agents are currently available for the treatment of fungal infections. Antimicrobial peptides (AMPs), which are natural molecules involved in the innate immune response of many organisms, represent a promising research method because of their broad killing activity. The aim of this study was to assess the activity of a frog AMP, [K3]temporin-SHa, against some species of yeasts and moulds, and to further explore its activity against Candida albicans. MIC determinations were performed according to EUCAST guidelines. Next, the activity of [K3]temporin-SHa against C. albicans was explored using time-killing curve experiments, membrane permeabilization assays, and electron microscopy. Finally, chequerboard assays were performed to evaluate the synergy between [K3]temporin-SHa and amphotericin B or fluconazole. [K3]temporin-SHa was found to be active invitro against several yeasts with MIC between 5.5 and 45 µM. [K3]temporin-SHa displayed rapid fungicidal activity against C. albicans (inoculum was divided into two in less than an hour and no viable colonies were recovered after 5 h) with a mechanism that could be due to membrane permeabilization. [K3]temporin-SHa was synergistic with amphotericin B against C. albicans (FICI = 0.303). [K3]temporin-SHa could represent an additional tool to treat several Candida species and C. neoformans.

Two New Compounds Containing Pyridinone or Triazine Heterocycles Have Antifungal Properties against Candida albicans.

Candidiasis, caused by the opportunistic yeast Candida albicans, is the most common fungal infection today. Resistance of C. albicans to current antifungal drugs has emerged over the past decade leading to the need for novel antifungal agents. Our aim was to select new antifungal compounds by library-screening methods and to assess their antifungal effects against C. albicans. After screening 90 potential antifungal compounds from JUNIA, a chemical library, two compounds, 1-(4-chlorophenyl)-4-((4-chlorophenyl)amino)-3,6-dimethylpyridin-2(1H)-one (PYR) and (Z)-N-(2-(4,6-dimethoxy-1,3,5-triazin-2-yl)vinyl)-4-methoxyaniline (TRI), were identified as having potential antifungal activity. Treatment with PYR and TRI resulted in a significant reduction of C. albicans bioluminescence as well as the number of fungal colonies, indicating rapid fungicidal activity. These two compounds were also effective against clinically isolated fluconazole- or caspofungin-resistant C. albicans strains. PYR and TRI had an inhibitory effect on Candida biofilm formation and reduced the thickness of the mannan cell wall. In a Caenorhabditis elegans infection model, PYR and TRI decreased the mortality of nematodes infected with C. albicans and enhanced the expression of antimicrobial genes that promote C. albicans elimination. Overall, PYR and TRI showed antifungal properties against C. albicans by exerting fungicidal activities and enhancing the antimicrobial gene expression of Caenorhabditis elegans.

Antifungal activity of peptide MSI-1 against Cryptococcus neoformans infection in vitro and in murine cryptococcal meningoencephalitis

The development of novel antifungal agents with high efficacy, low drug tolerance and few side effects is urgent. MSI-1 (GIWKFLKKAKKFWK-NH2), a cationic antimicrobial peptide, may be an attractive antifungal agent because of its structural characteristics, perfect stability against pH and high-temperature/salt, low toxicity towards mammalian cells and low potential for emergence of drug tolerance. In this study, the antifungal activity of MSI-1 in vitro and in a murine model of cryptococcal meningoencephalitis was evaluated. Zeta potential assay, flow cytometry, fluorescence microscope, transmission electron microscopy and microscale thermophoresis were performed to clarify the mechanisms underlying MSI-1 against C. neoformans. The results showed that MSI-1 exerted effective anti-cryptococcal activity in vitro, with MICs of 8−16 μg/mL and MFCs of 8−32 μg/mL, and in a C neoformans-infected mouse model, with significantly improved animal survival, decreased production of pro-inflammatory cytokines and alleviated lung injury, because the potent and rapid fungicidal activity of MSI-1 could effectively eliminate fungal counts in mouse organs. We confirmed that the positively charged peptide bound to C. neoformans by electrostatic attraction after interacting with glucuronoxylomannan (the primary component of C. neoformans capsule). Subsequently, MSI-1 increased the membrane fluidity of fungal cells and the cell membrane permeability, causing destabilized membrane integrity and leading to the final death of fungi. Collectively, MSI-1 possessed potent anti-cryptococcal activity via its notable membrane disruption effect and may be a potential candidate for use in antifungal infection induced by C. neoformans, especially azole-resistant cryptococcus.

Identification of a Phenylthiazole Small Molecule with Dual Antifungal and Antibiofilm Activity Against Candida albicans and Candida auris

Candida species are a leading source of healthcare infections globally. The limited number of antifungal drugs combined with the isolation of Candida species, namely C. albicans and C. auris, exhibiting resistance to current antifungals necessitates the development of new therapeutics. The present study tested 85 synthetic phenylthiazole small molecules for antifungal activity against drug-resistant C. albicans. Compound 1 emerged as the most potent molecule, inhibiting growth of C. albicans and C. auris strains at concentrations ranging from 0.25–2 µg/mL. Additionally, compound 1 inhibited growth of other clinically-relevant yeast (Cryptococcus) and molds (Aspergillus) at a concentration as low as 0.50 µg/mL. Compound 1 exhibited rapid fungicidal activity, reducing the burden of C. albicans and C. auris below the limit of detection within 30 minutes. Compound 1 exhibited potent antibiofilm activity, similar to amphotericin B, reducing the metabolic activity of adherent C. albicans and C. auris biofilms by more than 66% and 50%, respectively. Furthermore, compound 1 prolonged survival of Caenorhabditis elegans infected with strains of C. albicans and C. auris, relative to the untreated control. The present study highlights phenylthiazole small molecules, such as compound 1, warrant further investigation as novel antifungal agents for drug-resistant Candida infections.

Repurposing and Reformulation of the Antiparasitic Agent Flubendazole for Treatment of Cryptococcal Meningoencephalitis, a Neglected Fungal Disease.

ABSTRACTCurrent therapeutic options for cryptococcal meningitis are limited by toxicity, global supply, and emergence of resistance. There is an urgent need to develop additional antifungal agents that are fungicidal within the central nervous system and preferably orally bioavailable. The benzimidazoles have broad-spectrum antiparasitic activity but also have in vitro antifungal activity that includes Cryptococcus neoformans. Flubendazole (a benzimidazole) has been reformulated by Janssen Pharmaceutica as an amorphous solid drug nanodispersion to develop an orally bioavailable medicine for the treatment of neglected tropical diseases such as onchocerciasis. We investigated the in vitro activity, the structure-activity-relationships, and both in vitro and in vivo pharmacodynamics of flubendazole for cryptococcal meningitis. Flubendazole has potent in vitro activity against Cryptococcus neoformans, with a modal MIC of 0.125 mg/liter using European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodology. Computer models provided an insight into the residues responsible for the binding of flubendazole to cryptococcal β-tubulin. Rapid fungicidal activity was evident in a hollow-fiber infection model of cryptococcal meningitis. The solid drug nanodispersion was orally bioavailable in mice with higher drug exposure in the cerebrum. The maximal dose of flubendazole (12 mg/kg of body weight/day) orally resulted in an ∼2 log10CFU/g reduction in fungal burden compared with that in vehicle-treated controls. Flubendazole was orally bioavailable in rabbits, but there were no quantifiable drug concentrations in the cerebrospinal fluid (CSF) or cerebrum and no antifungal activity was demonstrated in either CSF or cerebrum. These studies provide evidence for the further study and development of the benzimidazole scaffold for the treatment of cryptococcal meningitis.

Discovery of a Membrane-Active, Ring-Modified Histidine Containing Ultrashort Amphiphilic Peptide That Exhibits Potent Inhibition of Cryptococcus neoformans

The new structural classes of ultrashort peptides that exhibit potent microbicidal action have potential as future drugs. Herein, we report that C-2 arylated histidines containing tripeptides His(2-Ar)-Trp-His(2-Ar) exhibit potent antifungal activity against Cryptococcus neoformans with high selectivity. The most potent peptide 12f [His(2-biphenyl)-Trp-His(2-biphenyl)] displayed high in vitro activity against C. neoformans (IC50 = 0.35 μg/mL, MIC = MFC = 0.63 μg/mL) with a selectivity index of >28 and 2 times higher potency compared to amphotericin B. Peptide 12f exhibited proteolytic stability, with no apparent hemolytic activity. The mechanism of action study of 12f by confocal laser scanning microscopy and electron microscopy indicates nuclear fragmentation and membrane disruption of C. neoformans cells. Combinations of 12f with fluconazole and amphotericin B at subinhibitory concentration were synergistic against C. neoformans. This study suggests that 12f is a new structural class of amphiphilic peptide with rapid fungicidal activity caused by C. neoformans.

Synthesis and antifungal evaluation of head-to-head and head-to-tail bisamidine compounds

Herein, we describe the antifungal evaluation of 43 bisamidine compounds, of which 26 are new, having the scaffold [Am]–[HetAr]–[linker]–[HetAr]–[Am], in which [Am] is a cyclic or acyclic amidine group, [linker] is a benzene, pyridine, pyrimidine, pyrazine ring, or an aliphatic chain of two to four carbon, and [HetAr] is a 5,6-bicyclic heterocycle such as indole, benzimidazole, imidazopyridine, benzofuran, or benzothiophene. In the head-to-head series the two [HetAr] units are oriented such that the 5-membered rings are connected through the linker, and in the head-to-tail series, one of the [HetAr] systems is connected through the 6-membered ring; additionally, in some of the head-to-tail compounds, the [linker] is omitted. Many of these compounds exhibited significant antifungal activity against Candida albicans, Candida krusei, Candida glabrata, Candida parapsilosis, and Cryptococcus neoformans (MIC⩽4μg/ml). The most potent compounds, for example, P10, P19 and P34, are comparable in antifungal activities to amphotericin B (MIC 0.125μg/ml). They exhibited rapid fungicidal activity (>3log10 decrease in cfu/ml in 4h) at concentrations equivalent to 4× the MIC in time kill experiments. The bisamidines strongly inhibited DNA, RNA and cell wall biosynthesis in C. albicans in macromolecular synthesis assays. However, the half-maximal inhibitory concentration for DNA synthesis was approximately 30-fold lower than those for RNA and cell wall biosynthesis. Fluorescence microscopy of intact cells of C. albicans treated with a bisamidine exhibited enhanced fluorescence in the presence of DNA, demonstrating that the bisamidine was localized to the nucleus. The results of this study show that bisamidines are potent antifungal agents with rapid fungicidal activity, which is likely to be the result of their DNA-binding activity. Although it was difficult to obtain a broad-spectrum antifungal compound with low cytotoxicity, some of the compounds (e.g., P9, P14 and P43) exhibited favorable CC50 values against HeLa cells and maintained considerable antifungal activity.

Current pharmacological concepts for wise use of echinocandins in the treatment of Candida infections in septic critically ill patients

Candida infections represent challenging causes of severe sepsis and/or of septic shock in the critically ill patients. Knowledge of current pharmacological concepts may promote a more wise use of echinocandins in the management of Candida infections in this setting. Echinocandins have some advantages over azoles, both pharmacodynamically (rapid fungicidal activity, anti-biofilm activity, unmodified activity against Candida isolates with decreased susceptibility to azoles and anti-cytokine/anti-chemokine activity) and pharmacokinetically (low interindividual variability, low potential for drug–drug interactions), that may influence the timing and the choice of therapy of Candida diseases in the critically ill patients. However, concerns exist in regards to the feasibility of fixed dosing regimens of echinocandins in all of the different patient populations and in regards to the effectiveness of echinocandin monotherapy in some clinical settings. In presence of deep-seated infections, voriconazole or liposomal amphotericin B may be valuable alternatives or add-on therapy.

Candidacidal effect of fluconazole and chlorhexidine released from acrylic polymer

To investigate the efficacy and rate of killing of a fluconazole- or chlorhexidine-impregnated polymeric delivery system against fluconazole-susceptible and -resistant Candida albicans and fluconazole-resistant Candida glabrata. Poly(ethyl methacrylate)/tetrahydrofurfuryl methacrylate (PEM/THFM) discs impregnated with chlorhexidine, pure fluconazole (FLCp) or fluconazole from capsules (FLCc) were prepared by substituting a portion of PEM powder with an equivalent amount of each drug. Discs were incubated in sterile water for 1, 3, 7, 14, 21 and 28 days. The amounts of drugs in the leachates were measured spectrophotometrically and their antifungal activity against fluconazole-susceptible (n=1) and fluconazole-resistant (n=2) candidal isolates was determined using a time-kill method and by comparing the released concentrations with the corresponding MICs. Fluconazole and chlorhexidine leached from PEM/THFM polymer for up to 28 days and the released concentrations were fungicidal against all three Candida isolates for at least the first 7 days. Chlorhexidine leachates killed all Candida isolates more rapidly than the two fluconazole formulation leachates throughout the study period. FLCc leachates required longer incubation for 100% killing than FLCp leachates. The proportion of viable C. glabrata dropped more slowly than that of C. albicans with the same MIC. The concentrations of chlorhexidine and fluconazole leached from the PEM/THFM polymer were fungicidal against all Candida isolates, including those resistant to fluconazole, for the first 7 days. Chlorhexidine leachates showed a rapid fungicidal activity for up to 4 weeks, which can be of use in cases with poor response to conventional antifungals.

Disseminated Candidiasis Caused by Candida albicans with Amino Acid Substitutions in Fks1 at Position Ser645 Cannot Be Successfully Treated with Micafungin

The clinical utility of the echinocandins is potentially compromised by the emergence of drug resistance. We investigated whether Candida albicans with amino acid substitutions at position Ser645 in Fks1 can be treated with either a conventional or an elevated dosage of micafungin. We studied Candida albicans (wild-type SC5314; MIC, 0.06 mg/liter) and four fks1 mutants (one FKS1/fks1 heterozygote mutant [MIC, 0.5 mg/liter] and three fks1/fks1 homozygous mutants [MICs for all, 2 mg/liter]) with a variety of amino acid substitutions at Ser645. The pharmacokinetic and pharmacodynamic relationships were characterized in a persistently neutropenic murine model of disseminated candidiasis. A mathematical model was fitted to all pharmacokinetic and pharmacodynamic data. This mathematical model was then used to "humanize" the murine pharmacokinetics, and the predicted antifungal effect was determined. The estimated maximal rate of growth and ultimate fungal densities in the kidney for each of the strains were similar. The administration of micafungin at 1 mg/kg of body weight to the wild type resulted in moderate antifungal activity, whereas the administration of 5 and 20 mg/kg resulted in rapid fungicidal activity. In contrast, the FKS1/fks heterozygote was killed only with 20 mg/kg, and the homozygous fks1 mutants failed to respond to any dosage. The bridging study revealed that human dosages of 100 and 400 mg/day were active only against the wild type, with no activity against either the heterozygote or the homozygote mutants. Ser645 Fks1 Candida albicans mutants cannot be treated with either conventional or elevated dosages of micafungin and should be deemed resistant.

The activity of polymethylene-bis-4-amino-quinaldinium salts against Pityrosporum ovale and Candida albicans.

Abstract A homologous series of polymethylene-bis-4-aminoquinaldinium salts has been shown to possess marked fungistatic activity against the potential pathogens Candida albicans and Pityrosporum ovale. The peak of antifungal activity against C. albicans occurs at a chain length (CH2)12, whilst against P. ovale the most active member of the series has a chain length (CH2)6. The decamethylene member (dequalinium), shows a potent and rapid fungicidal activity against both yeasts; quantitative data, from experiments involving short periods of drug-yeast contact, indicates that this activity of dequalinium is a function of the concentration of the quaternary compound and of the time of exposure.

Activity of antimicrobial peptide mimetics in the oral cavity: I. Activity against biofilms of Candida albicans

Naturally occurring antimicrobial peptides hold promise as therapeutic agents against oral pathogens such as Candida albicans but numerous difficulties have slowed their development. Synthetic, non-peptidic analogs that mimic the properties of these peptides have many advantages and exhibit potent, selective antimicrobial activity. Several series of mimetics (with molecular weight < 1000) were developed and screened against oral Candida strains as a proof-of-principle for their antifungal properties. One phenylalkyne and several arylamide compounds with reduced mammalian cytotoxicities were found to be active against C. albicans. These compounds demonstrated rapid fungicidal activity in liquid culture even in the presence of saliva, and demonstrated synergy with standard antifungal agents. When assayed against biofilms grown on denture acrylic, the compounds exhibited potent fungicidal activity as measured by metabolic and fluorescent viability assays. Repeated passages in sub-minimum inhibitory concentration levels did not lead to resistant Candida, in contrast to fluconazole. Our results demonstrate the proof-of principle for the use of these compounds as anti-Candida agents, and their further testing is warranted as novel anti-Candida therapies.

NB-002, a Novel Nanoemulsion with Broad Antifungal Activity against Dermatophytes, Other Filamentous Fungi, and Candida albicans

NB-002 is an oil-in-water emulsion designed for use for the treatment of skin, hair, and nail infections. The activity of NB-002 was compared to the activities of the available antifungal drugs against the major dermatophytes responsible for cutaneous infections, Trichophyton rubrum, Trichophyton mentagrophytes, Epidermophyton floccosum, and Microsporum spp., as well as 12 other genera of filamentous fungi. NB-002 consistently displayed fungicidal activity against all dermatophytes. The comparator compounds were either fungistatic or fungicidal, and for some strain-drug combinations, tolerance was observed. Assessment of the development of spontaneous resistance to NB-002 in different dermatophyte species yielded few stably resistant mutants. For filamentous nondermatophyte fungi, the MIC range varied from 0.06 to 0.5 microg/ml for Alternaria spp. to 2 to 8 microg/ml for Paecilomyes spp. NB-002 had activity against both azole-susceptible and -resistant Candida albicans yeast isolates, with MIC(90)s of 2 microg/ml, respectively, and minimum fungicidal concentrations at which 90% of isolates are inhibited of 4 and 8 microg/ml, respectively. The kinetics of the fungicidal activity of NB-002 against T. rubrum isolates were compared to those of the other antifungal drugs. NB-002 killed both mycelia and microconidia even when the fungal forms were dormant or not actively growing. Electron micrographs of mycelia and spores treated with NB-002 showed the significant disruption of the fungal structure. The in vitro broad coverage of NB-002 against filamentous fungi, dermatophytes, and C. albicans, as well as its rapid fungicidal activity, warrants further investigations to ascertain if NB-002 would be useful for the treatment of cutaneous mycoses.

In-Vitro Activity of the Synthetic Protegrin IB-367 Alone and in Combination with Antifungal Agents Against Clinical Isolates of Candida spp.

The in vitro activity of the peptide IB-367, alone or combined with either fluconazole (FLU) or amphotericin B (AMB), was investigated against 25 Candida isolates belonging to five species. IB-367 minimum inhibitory concentrations (MICs) ranged from 2.0 to 32 μg/ml and it was active against both FLU-susceptible and -resistant isolates. A rapid fungicidal activity was observed. Synergism was documented in 41.6% and 44% of IB-367/FLU and IB-367/AMB interactions, respectively. Antagonism was never observed. The broad antifungal activity and the positive interactions with AMB and FLU suggest that IB-367 represents a promising candidate against infections due to Candida spp.

In vitro antifungal susceptibilities of Candida albicans and other fungal pathogens to polygodial, a sesquiterpene dialdehyde.

In vitro antifungal activities of polygodial were investigated against several fungal pathogens. Polygodial showed strong antifungal activity, comparable to amphotericin B, against yeast-like fungi Candida albicans, C. utilis, C. krusei, Cryptococcus neoformans, Saccharomyces cerevisiae and also filamentous fungi including Trichophyton mentagrophytes, T. ruburum, and Penicillium marneffei. Other strains such as Aspergillus fumigatus, A. flavus, P. chrysogenum, C. lipolytica, and C. tropicalis showed moderate to low susceptibility to polygodial. The anti-fungal activity of polygodial was generally not reduced by several susceptibility-testing conditions such as medium, incubation temperature, inoculum size, and medium pH. However, polygodial's antifungal activity was strongly increased at acidic conditions. Unlike amphotericin B, polygodial did not show any hemolytic activity and also its antifungal activity was not diminished in the presence of ergosterol. Based on killing kinetics against growing and nongrowing C. albicans, polygodial showed strong and rapid fungicidal activity.