Flavonoid and carotenoid pigments in flower tissue of Sandersonia aurantiaca (Hook.)

Luteolin, cryptoxanthin and zeaxanthin were detected as the major pigments present in mature flowers of Sandersonia aurantiaca (Hook.). Both the flavonoids and carotenoid Figments were examined at four stages of flower development from green flower bud to senescent flower prior to tepal necrosis. The major component of the orange colour of the Sandersonia flowers is due to the presence of the carotenoids zeaxanthin and cryptoxanthin, both predominantly present in the esterified form. The main change during development is the loss of chlorophyll, beta-carotene and lutein, and the increase in zeaxanthin and cryptoxanthin as the flower matures from a green bud to an open flower. The major flavonoids present were luteolin and luteolin 7-O-glucoside. Flavonoid concentration decreased over the course of development to a mature flower but there was an increase in content per flower. The flavonoids were present in greater quantities than the carotenoids. However. as they absorb mostly in the UV region, they are not believed to contribute significantly to the observed colour. (C) 1998 Elsevier Science B.V.