Syntheses, spectral, X-ray and DFT studies of 5-benzyl-N-phenyl-1,3,4-thiadiazol-2-amine, 2-(5-phenyl-1,3,4-thiadiazol-2-yl) pyridine and 2-(5-methyl-1,3,4-thiadiazole-2-ylthio)-5-methyl-1,3,4-thiadiazole obtained by Mn(II) catalyzed reactions

An integrated approach towards the development of novel antifungal agents containing thiadiazole: synthesis and a combined similarity search, homology modelling, molecular dynamics and molecular docking study

Background

This study aims to synthesise and characterise novel compounds containing 2-amino-1,3,4-thiadiazole and their acyl derivatives and to investigate antifungal activities. Similarity search, molecular dynamics and molecular docking were also studied to find out a potential target and enlighten the inhibition mechanism.

Results

As a first step, 2-amino-1,3,4-thiadiazole derivatives (compounds 3 and 4) were synthesised with high yields (81 and 84%). The target compounds (6a–n and 7a–n) were then synthesised with moderate to high yields (56–87%) by reacting 3 and 4 with various acyl chloride derivatives (5a–n). The synthesized compounds were characterized using the IR, ¹H-NMR, ¹³C-NMR, Mass, X-ray (compound 7n) and elemental analysis techniques. Later, the in vitro antifungal activities of the synthesised compounds were determined. The inhibition zones exhibited by the compounds against the tested fungi, their minimum fungicidal activities, minimum inhibitory concentration and the lethal dose values (LD₅₀) were determined. The compounds exhibited moderate to high levels of activity against all tested pathogens. Finally, in silico modelling was used to enlighten inhibition mechanism using ligand and structure-based methods. As an initial step, similarity search was carried out and the resulting proteins that belong to Homo sapiens were used as reference in sequence similarity search to find the corresponding amino acid sequences in target organisms. Homology modelling was used to construct the protein structure. The stabilised protein structure obtained from molecular dynamics simulation was used in molecular docking.

Conclusion

The overall results presented here might be a good starting point for the identification of novel and more active compounds as antifungal agents.

Electronic supplementary material

The online version of this article (10.1186/s13065-018-0485-3) contains supplementary material, which is available to authorized users.

Ag(i), Cu(ii), Co(iii) and Hg(ii) complexes and metal-assisted products derived from 4-methyl-piperidine-carbodithioate: syntheses, structures, thermal analyses, redox behaviour and fluorescence properties

Ag(i), Cu(ii), Co(iii) and Hg(ii) complexes and metal-assisted products derived from 4-methyl piperidine have been synthesized. The Cu(ii) complex is redox reversible and compounds3and5are fluorescent.

Crystal structure of 5-(furan-2-yl)-N-phenyl-1,3,4-oxa-diazol-2-amine

The title compound, C12H9N3O2, was obtained as a cyclized oxa-diazole derivative from substituted thio-semicarbazide in the presence of manganese(II) acetate. The furan ring is disordered over two orientations, with occupancies of 0.76 (2) and 0.24 (2). The dihedral angles between the central oxa-diazole ring and the pendant phenyl ring and furan ring (major disorder component) are 3.34 (18) and 5.7 (6)°, respectively. A short intra-molecular C-H⋯O contact generates an S(6) ring. In the crystal, inversion dimers linked by pairs of N-H⋯N hydrogen bonds generate R 2 (2)[8] loops. The dimers are linked by C-H⋯π and π-π inter-actions [range of centroid-centroid distances = 3.291 (2)-3.460 (8) Å], generating a three-dimensional network.