The sensitivity of carthamin and safflor yellow B colours towards redox substances

Abstract

The sensitivities of carthamin and safflor yellow B towards oxidants and antioxidants were compared in bufferized solutions at various given concentrations. The test chemicals affected variously on the pigment colourations: (1) externally charged 0<sub>2</sub> had less effect on the colour change of carthamin, (2) organe-yellow coloured safflor yellow B was bleached by the gas flush, (3) carthamin showed little or no affinitive property for H<sub>2</sub>0<sub>2</sub> at 0.001-230 µM level, (4) safflor yellow B reacted positively with the oxidant and was changed readily to faint yellow unknown compounds, (5) double-faced responses could be found in carthamin solution with L-ascorbic acid or with D-isoascorbic acid, namely the former antioxidant intensified the colour of carthamin and the latter reduced the red colouration, (6) hydroquinone emphasized the red colour of carthamin in solution, (7) safflor yellow B shifted bathochromically in hydroquinone containing solution, however, it showed no shift in L-ascorbic acid and D-isoascorbic acid solutions. The data are discussed from the standpoint of oxidative dissimilation of the quinochalconoids in the floral tissues of dyer's saffron capitula.