Steroid sapogenins ofDigitalis ciliata Trautv
SummaryTigogenin and gitogenin have been isolated from the leaves and flowers, and digitogenin (0.283%) and tigogenin (0.062%) from the seeds ofD. ciliata Trautv. The presence of gitogenin in the seeds has also been established by paper chromatography.
A preliminary phytochemical investigation of Digitalis ferruginea.
The cardiac glycosides of the fresh first-year leaves of Digitalis ferruginea have been resolved into alpha acetyl digitoxin and an amorphous glycoside whose properties resemble digitoxin. The saponin tigonin was also very readily isolated in the amount of about two per cent of the dry weight of the leaves.
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.