Changes in some carotenoids and apocarotenoids during flower development in Boronia megastigma (Nees)

The carotenoid profile of an acetone extract from the flowers and leaves of Boronia megastigma (Nees) was examined. A comparison was made of the major carotenoids found in boronia flowers and leaves. The C-40 carotenoids beta-carotene, zeaxanthin, lutein, and neoxanthin were positively identified in boronia flowers using known standards, UV-vis spectra, and mass spectrometry. Two other carotenoids were tentatively assigned as the palmitic acid ester of 3-hydroxy-10'-apocaroten-10'-oic acid and 9,15,9'-tri-cis-zeta-carotene. Additionally, changes in the levels of C-40 carotenoids, C-27 apocarotenoids, and beta-ionone during flower development were measured. Significant increases in beta-carotene and apocarotenoids that could be derived from cleavage in the 9,10-position, including beta-ionone and various C-27 apocarotenoids, were observed at the time of flower opening. An increase in lutein, which is derived through an alternative biosynthetic pathway, was not observed during flower opening, thus indicating the possibility that the beta-carotene pathway was activated during flower opening in boronia. The understanding of these processes may assist in optimizing harvest and postharvest processes useful to the boronia extraction industry.