Furan derivatives. Their common molecular denominator responsible for bleaching of Euglena gracilis.

Abstract

We studied the effect of 38 furan derivatives on the green micro-organism Euglena gracilis and on Bacillus subtilis and Escherichia coli, with the aim of finding the common molecular denominator responsible for bleaching of Euglena gracilis by furan derivatives. The results confirmed that the nitro-group in position 5 of the furan nucleus is essential to the bleaching activity of these derivatives. It was also found, however, that the substituent in position 2 of the furan nucleus was likewise important. Only 5-nitrofuran derivatives with a −CH=N−linkage in position 2 of the furan nucleus (Schiff bases) are active bleachers. Derivatives with a −CH=CH− linkage are weak bleachers and derivatives with a thiourea at this site have no bleaching activity at all. All 5-nitrofurans and some bromo- or iodo-furans were active against Bacillus subtilis, but not one of the tested derivatives was active against Escherichia coli.