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The occurrence of the anti-inflammatory flavonoids hypolaetin 8-glucoside, cirsiliol and sideritoflavone, and other flavonoids has been investigated in taxonomically related taxa of the genus Sideritis by HPLC. All the analysed taxa showed very similar flavonoid aglycone patterns, while they had clear differences in the flavonoid glycoside patterns. The analyses of flavonoid glycosides allowed the differentiation of five different groups of Sideritis taxa. There is a correlation between the chemical groups and the geographical location of the analysed taxa. In S. mugronensis, S. tragoriganum and S. reverchonii , the flavonoids hypolaetin 8-glucuronide, hypolaetin 4′-methyl ether 8-glucoside and 8-glucuronide have also been identified, this being the first time that these substances are reported in the Labiatae.

Subject and Source Micromeria albanica (Gris. ex K. Maly) ~ilic, M. thymifolia (Scop.) Fritsch., M. dalrnadca Bentham, M. juliana (L.) Bentham ex Gris.,/14. cristata (Hampe) Gris., M. parviflora Reichenb., M. graeca (L.) Bentham, M. pseudocroatica ~ilic and M. croatica (Pers.) Schott. were collected in Yugoslavia. Vouchers are deposited in the Herbarium of the Botanical Institute and Garden at Belgrade.

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.