The relationship between pyrethrins and the yellow pigmentation in pyrethrum flowers

Various clones and varieties of Chrysanthemum cinerariaefolium flowers originating from various localities were used in this study to establish the link between pyrethrins and the yellow pigments in pyrethrum. Pyrethrins content was determined using spectrophotometric, AOAC and HPLC analytical techniques. Absorbances of I % (w/v) n-hexane extracts at various wavelengths in the UV and visible regions were read using a double beam spectrophotometer. This paper presents correlations between total Pyrethrins, individual ester distributions, Pyrethrins I and Pyrethrins11 ratios and specific colour absorbances (A1%1cm) in three different regions 260-300nm (1A1%cm), 300-400 nm (2A1%cm) and 400-470 nm (3A1%cm). The results depict negative colour absorbances in all the three regions. The pigments absorbing at 266-300 nm show a better correlation with the pyrethrins than pigments absorbing at 400- 470 nm. The pigments at the former region are flavonoids and the latter carotenoids from spectrophotometric scans and TLC screening. African Journal of Science and Technology Vol.4(2) 2003: 116-123