1,2,4-Triazolo-quinazoline-thiones: Non-conventional synthetic approach, study of solvatochromism and antioxidant assessment

Abstract

A non-conventional methodology has been utilized for the synthesis of a series of 1,2,4-triazolo-quinazoline-thiones (2a-l). Here the reaction was carried out between 1,2,4-triazolo-quinazolinones (1a-l), in the presence of 1,4-dioxane. The mixture was irradiated under microwave (100W) for 7min to obtain targeted molecules (2a-l). All the synthesized molecules were confirmed by (1)H, (13)C NMR and HRMS. The solvatochromic property (absorption spectra) of compounds (2a-l) in solvents of different polarities was studied. The compounds (2a-l) were further subjected for their in vitro free radical screening using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and also screened for their in vitro anti-fungal property against Aspergillus flavus (A. flavus) and Aspergillus niger (A. niger). The results from free radical scavenging assay showed promising activity for compounds 2a, e-i, whereas compound 2d showed significant antioxidant activity when compared to ascorbic acid. In vitro anti-fungal study showed that the 1,2,4-triazolo-quinazoline-thiones (2a-l) had significant activity against A. flavus and A. niger compared with widely used antifungal agent Fluconazole.

Keywords: 1,2,4-Triazolo-quinazoline-thiones; Free radical scavenging activity; Lawesson reagent; Organosulfur; UV–visible spectroscopy.