The distribution of methylated flavones in the Lamiaceae

The lipophilic flavones, 5,6,4′-trihydroxy-7,8,3′-trimethoxyflavone (thymonin), and 5,6,4′-trihydroxy-7,3′-dimethoxyflavone have been surveyed in 24 genera of the subfamily Nepetoideae (Lamiaceae). These flavonoids are deposited externally on the leaf surfaces, and they have been found in species of the taxonomically related Acinos, Micromeria, Satureja, Calamintha, Mentha, Thymbra, Thymus and Origanum. Other 5,6-dihydroxyflavones such as thymusin (5,6,4′-trihydroxy-7,8-dimethoxyflavone), pebrellin (5,6,-dihydroxy-7,8,4′-trimethoxyflavone), 5,6-dihydroxy-7,8,3′,4′-tetramethoxyflavone, ladanein (5,6-dihydroxy-7,4′-dimethoxyflavone) and 5,6-dihydroxy-7,3′,4′-trimethoxyflavone have been detected but they are relatively rare. The chemotaxonomic applications of this flavonoid data are discussed.