Accumulation of furanic labdane diterpenes in Marrubium vulgare and Leonurus cardiaca.

Accumulation of furanic labdane diterpenes has been investigated in different parts of field-grown plants of MARRUBIUM VULGARE (Lamiaceae) and LEONURUS CARDIACA (Lamiaceae). Furanic labdane diterpenes were produced and accumulated only in the aerial parts. Greatest amounts were measured in leaves and flowers. Up to 4 mg furanic labdane diterpenes per g fresh weight were found. Accumulation of furanic labdane diterpenes in plantlets seemingly depends on a developmental programme. No furanic labdane diterpenes were detected in plantlets during the first four to five weeks following germination. At this time the leaves became more differentiated and the number of trichomes on leaves was obviously increasing. Young leaves and buds contained most furanic labdane diterpenes. It was proven that at least a part of the non-volatile furanic labdane diterpenes is stored in peltate glandular trichomes. NMR signals of marrubiin were investigated with correlated spectra. Some (1)H- and (13)C-NMR assignments reported in literature were revised.