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Five coumarins and two flavonoid glycosides are reported from Philotheca pinoides of which one, 3-(3-hydroxy-3-methylbut-1-enyl)-7,8-dimethoxycoumarin, appears to be novel. HPLC analysis of extracts of a number of other Philotheca species revealed that 5,7-dioxygenated-6,8-prenylated coumarins were present in P. apiculata, P. coccinea, P. deserti, P. pachyphylla, P. rhomboidea, P. thryptomenoides and P. gardneri, but not in P. nodiflora, P. pinoides, P. sericea, P. spicata, P. tomentella or P. woganensis. An analysis of the distribution of coumarins demonstrate that Geleznowia verrucosa is chemically indistinguishable from many species of Philotheca section Philotheca, whereas Philotheca section Erionema is more variable. Typical avicennol type coumarins have been found in the Boronieae only in Philotheca section Philotheca, in Geleznowia and in one species of Asterolasia. Coumarins that characterise Philotheca section Philotheca are not currently known from Eriostemon s.s., and sympatric genera such as Phebalium and Drummondita. |
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