Synthesis and photophysical studies of new benzo[a]phenoxazinium chlorides as potential antifungal agents

Abstract

A set of four new benzo[a]phenoxazinium chlorides possessing ethyl, propyl, decyl and tetradecyl groups at the 9-amino function of the heterocycle along with a propyl group at the 5-amino position was efficiently synthesised. These compounds displayed fluorescence with maximum emission wavelengths of 673 and 685 nm, in anhydrous ethanol and water. All the benzo[a]phenoxazines were evaluated against the yeast Saccharomyces cerevisiae in a broth microdilution assay. It was found that their antifungal activity depended on the variation in the lengths of the aliphatic chains. The highest MIC activity of 1.56 µM was obtained for compound 7 comprising a di-alkylated propyl substituent at 9-amino position and a propyl chain at the 5-amino position of the heterocycle core.