In vitro and in silico evaluation of antifungal potential of 2-amino-5-(3-nitrophenyl)-1,3,4-thiadiazole against aspergillus niger: implications for nanotechnology-based antifungal design

Abstract

The antifungal activity of 2-Amino-5-(3-nitrophenyl)-1,3,4-thiadiazole is investigated against Aspergillus niger using combined experimental and computational approaches. The compound is synthesized via a one-step cyclization reaction and structurally characterized using FT-IR and ¹H NMR spectroscopy, confirming its chemical integrity. In vitro agar well-diffusion assays demonstrated significant, concentration-dependent inhibition of fungal growth, with the highest activity observed at 5000 µg/mL. Density Functional Theory (DFT) calculations revealed a HOMO–LUMO gap of 3.709 eV and intramolecular charge transfer characteristics, suggesting electronic stability and reactivity. Homology modeling of A. niger sterol 14-α-demethylase (CYP51) is performed using CYP51B from Aspergillus fumigatus (PDB ID: 6CR2) as the template, and model validation using MolProbity and QMEANDisCo confirmed high stereochemical quality. Molecular docking showed favorable binding interactions of the compound within the heme-containing active site, while QSAR analysis further supported structure-activity relationships correlating molecular features with antifungal potency. Collectively, these results highlight 2-Amino-5-(3-nitrophenyl)-1,3,4-thiadiazole as a promising lead for antifungal drug development against A. niger. From a nanotechnology perspective, the molecular size, electronic structure, and surface-interaction capability of 2-Amino-5-(3-nitrophenyl)-1,3,4-thiadiazole suggest its suitability for incorporation into nano-enabled antifungal systems. The compound’s favorable electronic properties, strong binding affinity to CYP51, and concentration-dependent biological activity support its potential use in nanoparticle-based delivery platforms or nano-structured coatings aimed at enhancing antifungal efficacy and selectivity. These findings highlight the relevance of the present study for the rational design of nanotechnology-driven antifungal therapeutics.