Cardiovascular activity of a methanolic extract of Digitalis purpurea spp. heywoodii

[Panciu Corina-Maria]

Digitalis heywoodii is a subspecies (ssp) of Digitalis purpurea L. that has not been thoroughly investigated. Differences and similarities exists between D. purpurea spp. heywoodii and D. pupurea from botanical (Silva and Silva, 1959; Werner, 1966; Valdes, 1987; Ayuso et al., 1991) and phytochemical (Lungeanu et al., 1963; Lungeanu, 1968) perspectives. This subspecies was discovered by Silva and Silva in 1959, however, no pharmacological study has been carried out on this taxon until now because of its small habitat. The presence of steroid glycosides in leaves of D. purpurea spp. heywoodii, was described by Langeanu et al., in 1963. Eight compounds have been isolated: lanatoside A, lanatoside B, purpurea glycoside A, purpurea glycoside B, glucoevatromonoside, glucolanatoside, digitalinum verum and strospeside. Although pharmacological effects of the plant extracts have been found previously (Ayuso et al., * Corresponding author. 1993; Navarro et al., 1994), it was decided to broaden the understanding about their cardiovascular activity. In 1930 Smith investigated an alternative plant source, the Digitalis lanata, and isolated from it the compound digoxin that is now commonly used when a cardiac glycoside is required. When in 1933 Stoll and Kreis crystallised digilanids, lanatosides A, B and C from D. lanata, the major components of both D. purpurea and D. lanata had been characterised (Stoll and Kreis, 1933). From a methanolic extract of leaves of D. purpurea spp. heywoodii we have identified four cardenolides: digitalinum verum, strospeside, purpureaglycoside A, and lanatoside A by its relative R as well as by direct comparison with authentic samples. On the other hand, a quantitative relationship does appear to exist between the cardiac action of extract and its emetic activity. The emetic potency of extract and digoxin was similar with doses 0.5 mg/kg and 40 mg/kg, respectively. In conclusion, early results of the pharmacological activity of methanolic extract of D. purpurea spp. heywoodii demonstrate that this plant has an interesting biological activity, due to the digitalis compounds present on it. There is a good methanolic extract: digoxin relationship with respect to the dose-response obtained with the different tests and the presence of gitoxin derivatives (digitalinum verum, strospeside). These compounds have been very rarely mentioned in the pharmacological literature (Abiko et al., 1965; Abiko and Ito, 1967; Abiko, 1967).

Cardiovascular activity of a methanolic extract of Digitalis purpurea spp. heywoodii