Digitalis lanata Ehrh. – Woolly foxglove

Digitalis lanata is a biennial, herbaceous plant in Plantaginaceae family (TH). In the first year of the vegetation only leaf rosettes develop, which are 15-30 cm long, lanceolate and glossy. The flowers bloom in the second year, the flower stems are 80-120 cm tall the leaves are alternate, acute, lanceolate and they don’t have stalks. The thimble-shaped flowers are located in loose, terminal racemes, the petals are white with brown netting, the bracts and sepals are covered with woolly hair. The flowers bloom in the beginning of June. The small, reddish brown seeds develop in pods that have small hooks. Thousand seed weight: 0.4-0.5 g. From the closely related purple foxglove (Digitalis purpurea) Digitalis lanata can be easily distinguished by the different morphological features: woolly, wrinkled, oval leaves, purple flowers in terminal racemes.

Woolly foxglove distributed through South-Eastern Europe, in Hungary it can occur wildly: several populations are known in Buda hills and in Mecsek. The plant grows well in dry, warm places. The natural populations of Digitalis lanata are highly protected; the commercial drug can originate only from cultivated plants.

The official drug of the plant is the dried leaf: Digitalis lanatae folium. The quality requirements are written in the Hungarian Standards (MSZ 19855-1968), the drug is also mentioned by the German Pharmacopoeia (DAB 9).

The active agents of woolly foxglove are cardenolides (triterpene steroids): lanatoside C glycoside and its aglycon digoxigenin, which is responsible for the biological activity. The whole plant accumulates cardenolids, but the leaf rosettes have the highest steroid content (0.2-0.6 %). Flavonoids and saponins are also active agents of the drug.

Digitalis lanata has been applied for treating poor cardiac functions for a long time. The drug is an important material for pharmaceutical industry, several medicaments are made from digoxigenin (¢Digoxin¢, ¢Isolanid¢, ¢Neoadigan¢). These medicaments can be applied only with constant, medical control. The overdoses can cause toxic symptoms, such as nausea, visual disorders or rare pulse. During the utilization of foxglove medicaments breaks should be kept in application, because both the steroid glycosides and the aglycones can cumulate in the body.