thiourea and Candidiasis

Mannich bases and its derivatives are regarded as supreme pharmacophores in therapeutics. The study investigates the antimycotic potential of Mannich bases, 1-((1H-benzimidazol-1-yl) methyl) urea (C1) and 1-((3-hydroxynapthalen-2-yl) methyl) thiourea (C2), against Candida albicans. Biofilm and hyphal inhibitory activities of the Mannich bases were tested by crystal violet quantification, fluorescence imaging cAMP rescue, qRT PCR, and by molecular docking analysis. The compounds inhibited the biofilms of C. albicans and restrained the filamentation abilities of the pathogen. Structure-activity relationship studies revealed that the presence of urea or thiourea moiety in the tail section is essential for interacting with adenylate cyclase (AC). The Mannich bases seemed to block Ras-cAMP-PKA pathway by inhibiting second messenger activity required for hyphal induction and biofilm formation. In conclusion, the study warrants point-of-care testing of C1/C2 and provides a starting point for deriving several structurally modified Mannich bases which might plausibly replace the prevailing antimycotic drugs in future.

Topics: Antifungal Agents; Biofilms; Candida albicans; Candidiasis; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Fungal Proteins; Humans; Mannich Bases; Molecular Docking Simulation; ras Proteins; Signal Transduction; Thiourea

Eukaryotic transcription activators stimulate the expression of specific sets of target genes through recruitment of co-activators such as the RNA polymerase II-interacting Mediator complex. Aberrant function of transcription activators has been implicated in several diseases. However, therapeutic targeting efforts have been hampered by a lack of detailed molecular knowledge of the mechanisms of gene activation by disease-associated transcription activators. We previously identified an activator-targeted three-helix bundle KIX domain in the human MED15 Mediator subunit that is structurally conserved in Gal11/Med15 Mediator subunits in fungi. The Gal11/Med15 KIX domain engages pleiotropic drug resistance transcription factor (Pdr1) orthologues, which are key regulators of the multidrug resistance pathway in Saccharomyces cerevisiae and in the clinically important human pathogen Candida glabrata. The prevalence of C. glabrata is rising, partly owing to its low intrinsic susceptibility to azoles, the most widely used antifungal agent. Drug-resistant clinical isolates of C. glabrata most commonly contain point mutations in Pdr1 that render it constitutively active, suggesting that this transcriptional activation pathway represents a linchpin in C. glabrata multidrug resistance. Here we perform sequential biochemical and in vivo high-throughput screens to identify small-molecule inhibitors of the interaction of the C. glabrata Pdr1 activation domain with the C. glabrata Gal11A KIX domain. The lead compound (iKIX1) inhibits Pdr1-dependent gene activation and re-sensitizes drug-resistant C. glabrata to azole antifungals in vitro and in animal models for disseminated and urinary tract C. glabrata infection. Determining the NMR structure of the C. glabrata Gal11A KIX domain provides a detailed understanding of the molecular mechanism of Pdr1 gene activation and multidrug resistance inhibition by iKIX1. We have demonstrated the feasibility of small-molecule targeting of a transcription factor-binding site in Mediator as a novel therapeutic strategy in fungal infectious disease.

Topics: Animals; Antifungal Agents; Binding Sites; Candida glabrata; Candidiasis; DNA-Binding Proteins; Drug Resistance, Fungal; Drug Resistance, Multiple, Fungal; Fluconazole; Fungal Proteins; Gene Expression Regulation, Fungal; Hydrazines; Ketoconazole; Mediator Complex; Mice; Models, Molecular; Nuclear Magnetic Resonance, Biomolecular; Protein Binding; Protein Structure, Tertiary; Saccharomyces cerevisiae Proteins; Thiourea; Trans-Activators; Transcription Factors; Transcriptional Activation; Up-Regulation

Topics: Amphotericin B; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Bacterial Infections; Candida albicans; Candidiasis; Escherichia coli; Escherichia coli Infections; Mice; Neomycin; Nystatin; Penicillins; Polymyxins; Staphylococcal Infections; Streptomycin; Tetracycline; Thiourea; Undecylenic Acids

Topics: Acetylcholine; Administration, Topical; Animals; Anti-Bacterial Agents; Anti-Infective Agents; Anti-Inflammatory Agents; Antifungal Agents; Arthritis; Arthrodermataceae; Bacteria; Blood Pressure; Burns; Candida; Candidiasis; Carrageenan; Depression, Chemical; Dextrans; Gastrointestinal Motility; Guinea Pigs; Hindlimb; Kaolin; Mice; Rabbits; Rats; Staphylococcal Infections; Thiourea