Benzoxazinoids and iridoid glucosides from four Lamium species.

A new class of compounds for the plant family Lamiaceae, benzoxazinoids, was found in Lamium galeobdolon. From the aerial parts of the species were isolated the new 2-O-beta-D-glucopyranosyl-6-hydroxy-2H-1,4-benzoxazin-3(4H)-one (6-hydroxy blepharin) together with four known benzoxazinoids, DHBOA-Glc, blepharin, DIBOA, DIBOA-Glc, as well as harpagide, 8-O-acetyl-harpagide and salidroside. Eight known iridoid glucosides, 24-epi-pterosterone and verbascoside were isolated from Lamium amplexicaule, L. purpureum and L. garganicum. The iridoids, 5-deoxylamiol and sesamoside, as well as the phytoecdysone, 24-epi-pterosterone, were found for the first time for the genus Lamium. The phytochemical data are discussed from a systematic and evolutionary point of view.