Distribution and taxonomic implications of some phenolics in the family Lamiaceae determined by ESR spectroscopy

The dihydric phenolics from the leaves of 365 specimens representing 355 species and varieties of 110 genera of Lamiaceae (Labiatae) have been examined as semiquinones by ESR spectroscopy. Of these 89 genera comprising 194 species belong to the Lamiaceae, whereas 21 genera comprising 161 species have been transferred from the Verbenaceae in the most recent classification. Two chemical characters give strong support to the subfamily division of the Lamiaceae as recognised by Erdtman (1945). (Svensk Bet. Tidskr. 29, 279-285) and others. Rosmarinic acid was observed in 110 species out of 127 studied and confined to the subfamily Nepetoideae sensu Erdtman. These species produce tricolpate pollen grains. 3,4-Dihydroxyphenylethanoid glycosides were observed in 111 species all confined to Lamioideae sensu Erdtman with hexacolpate pollen grains. The acid and the phenylethanoid glycosides were found to be mutually exclusive, apart from one species, Teucrium scorodonia. A compound tentatively assigned as a beta-hydroxy-(3,4-dihydroxyphenyl) ethanoid glycoside, was observed in 49 species, solely confined to subfamily Lamioideae. Furthermore, rosmarinic acid was observed in Aegiphila mollis and in Hymenopyramis brachiata, both belonging to Lamioideae. No phenylethanoid glycosides were observed from any of 5 Hymenopyramis or from any of 30 species of Vitex. The latter result questions the transfer of the genus to Lamiaceae, but strengthens its isolated position. Chlorogenic acid was observed in 34 species and protochatechuic acid in 16 species. Hydroquinone is scattered in the family (4 species) and thymohydroquinone was observed in 7 species all belong to the Nepetoideae. (C) 2000 Elsevier Science Ltd. All rights reserved.