Antifungal activity of alexidine dihydrochloride in a novel diabetic mouse model of dermatophytosis

Alexidine as a Potent Antifungal Agent Against Candida Hemeulonii Sensu Stricto

The increasing prevalence of infections byCandida hemeulonii sensu stricto, particularly due to its resistance to standard antifungal therapies, represents a significant healthcare challenge. Traditional treatments often fail, emphasizing the need to explore alternative therapeutic strategies. Drug repurposing, which reevaluates existing drugs for new applications, offers a promising path. This study examines the potential of repurposing alexidine dihydrochloride as an antifungal agent againstC. hemeulonii sensu stricto. Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) values were established using broth microdilution methods. To further assess antifungal activity, different assays were conducted, including growth inhibition, biofilm inhibition, biofilm eradication, and cell damage. Checkerboard assays were employed to study the compound's fungicidal potential and interactions with other antifungals. Additional tests, sorbitol protection assay, efflux pump inhibition, cell membrane permeability assays, and nucleotide leakage were performed. In vivo efficacy and safety were evaluated inTenebrio molitor larvae. Alexidine demonstrated fungicidal activity againstC. hemeulonii sensu stricto, with an MIC of 0.5 μg/mL. Biofilm formation was significantly inhibited, with a reduction of 78.69%. Mechanistic studies revealed nucleotide leakage, indicating membrane impact, but no significant protein leakage was detected. In vivo, alexidine displayed a favorable safety profile, with no evidence of hemolysis or acute toxicity in the T. molitor model. These findings support alexidine as a strong candidate for antifungal drug repurposing, especially for treatingC. hemeulonii sensu stricto infections. Its efficacy in inhibiting growth and biofilm formation, combined with a positive safety profile, underscores its potential for clinical development as an antifungal therapy.

Naamidine A reveals a promising zinc-binding strategy for topical antifungal therapy

Fungal disease affects over a billion people worldwide. Naamidine A inhibits the growth of diverse fungal pathogens through an unknown mechanism. Here, we show that the supplementation of medium with excess zinc abolishes the antifungal activity of naamidine A. Furthermore, we highlight that naamidine A has in vitro activity against terbinafine-resistant Trichophyton spp. and in vivo efficacy in a mouse model of dermatomycosis caused by T. mentagrophytes, highlighting its therapeutic potential as a topical treatment.

Clinical Use of Super-Bioavailable Itraconazole for the Management of Dermatophytosis: Consensus Statement by Dermatologists from India via the Modified Delphi Technique

Super-bioavailable itraconazole (SB ITZ) overcomes the limitations of conventional itraconazole (CITZ) such as interindividual variability and reduced bioavailability. It has been approved for systemic mycoses in Australia and Europe as 50 mg and the USA as 65 mg and in India as 50 mg, 65 mg, 100 mg, and 130 mg. However, data on the ideal dose and duration of SB ITZ treatment in managing dermatophytosis are insufficient. This consensus discusses the suitability, dosage, duration of treatment, and relevance of using SB ITZ in managing dermatophytosis in different clinical scenarios. Sixteen dermatologists (>15 years of experience in the field and ≥2 years clinical experience with SB ITZ), formed the expert panel. A modified Delphi technique was employed, and a consensus was reached if the concordance in response was >75%. A total of 26 consensus statements were developed. The preferred dose of SB ITZ is 130 mg once daily and if not tolerated, 65 mg twice daily. The preferred duration for treating naïve dermatophytosis is 4-6 weeks and that for recalcitrant dermatophytosis is 6-8 weeks. Moreover, cure rates for dermatophytosis are a little better with SB ITZ than with CITZ with a similar safety profile as of CITZ. Better patient compliance and efficacy are associated with SB ITZ than with CITZ, even in patients with comorbidities and special needs such as patients with diabetes, extensive lesions, corticosteroid abuse, adolescents, and those on multiple drugs. Expert clinicians reported that the overall clinical experience with SB ITZ was better than that with CITZ.

Allosteric inhibition of tRNA synthetase Gln4 by N-pyrimidinyl-β-thiophenylacrylamides exerts highly selective antifungal activity

Candida species are among the most prevalent causes of systemic fungal infections, which account for ∼1.5 million annual fatalities. Here, we build on a compound screen that identified the molecule N-pyrimidinyl-β-thiophenylacrylamide (NP-BTA), which strongly inhibits Candida albicans growth. NP-BTA was hypothesized to target C. albicans glutaminyl-tRNA synthetase, Gln4. Here, we confirmed through in vitro amino-acylation assays NP-BTA is a potent inhibitor of Gln4, and we defined how NP-BTA arrests Gln4's transferase activity using co-crystallography. This analysis also uncovered Met496 as a critical residue for the compound's species-selective target engagement and potency. Structure-activity relationship (SAR) studies demonstrated the NP-BTA scaffold is subject to oxidative and non-oxidative metabolism, making it unsuitable for systemic administration. In a mouse dermatomycosis model, however, topical application of the compound provided significant therapeutic benefit. This work expands the repertoire of antifungal protein synthesis target mechanisms and provides a path to develop Gln4 inhibitors.

Antibacterial and Antibiofilm Properties of the Alexidine Dihydrochloride (MMV396785) against Acinetobacter baumannii

Antibiotic-resistant Acinetobacter baumannii infections among patients in hospital settings are rising at an alarming rate. The World Health Organization has designated carbapenem-resistant A. baumannii as a priority pathogen for drug discovery. Based on the open drug discovery approach, we screened 400 compounds provided as a Pandemic Response Box by MMV and DNDi to identify compounds with antibacterial and antibiofilm activity against two A. baumannii reference strains using a highly robust resazurin assay. In vitro screening identified thirty compounds with MIC ≤ 50μM having growth inhibitory properties against the planktonic state. Five compounds, with MMV IDs MMV396785, MMV1578568, MMV1578574, MMV1578564, and MMV1579850, were able to reduce metabolically active cells in the biofilm state. Of these five compounds, MMV396785 showed potential antibacterial and antibiofilm activity with MIC, MBIC, and MBEC of 3.125 μM, 12.5, and 25-100 µM against tested A. baumannii strains, respectively, showing biofilm formation inhibition by 93% and eradication of pre-formed biofilms by 60-77.4%. In addition, MMV396785 showed a drastic reduction in the surface area and thickness of biofilms. Further investigations at the molecular level by qRT-PCR revealed the downregulation of biofilm-associated genes when exposed to 50 µM MMV396785 in all tested strains. This study identified the novel compound MMV396785 as showing potential in vitro antibacterial and antibiofilm efficacy against A. baumannii.