C-methyl-flavonoids from the leaf waxes of some Myrtaceae.

The thin waxy coatings on leaves of nine species of Callistemon, two of Melaleuca and one species of Metrosideros, have been studied for the occurrence of leaf surface flavonoids. The Callistemon species and Metrosideros robusta exhibit only C-methylated flavonoids, while O-methyl flavonoids were detected in Melaleuca huegelii. The new natural C-methyl flavonol, 5,7-dihydroxy-3,8,4'-trimethoxy-6-C-methylflavone, was isolated from Metrosideros robusta. The leaf wax of Callistemon coccineus contains the novel C-methylflavonoid, 5,4'-dihydroxy-8-C-methyl-7-methoxy flavanone.