Türkiye?ye endemik Digitalis L. türlerinin kallus kültürlerinde stress faktörleri ile kardenolitler de dahil belli metabolitler arasındaki ilişkinin araştırılması

The genus Digitalis L., whose Latin name is ?finger of a glove? referring to the shape of the flowers, is a member of the Plantaginaceae. Members of the genus Digitalis are medicinally and economically important plants which contain important cardioactive compounds used to treat heart problems. The plant is well-known in Turkey for its cardenolides (glycosides) content, which is used for myocardial infarction, edema, angina, cardiac dysfunction, hyertropy and arterial hypertension. Commercial production of bioactive secondary metabolites by traditional agriculture is an inefficient process. Strategies, based on in vitro culture methods, have been extensively studied to improve the production of specific plant derived chemicals. The aim of the present research is to obtain relationship between different stress treatments and content of cardiotonic glycosides (digoxigenin, gitoxigenin, lanatoside C, digoxin and digitoxin) as secondary metabolites of commercial valuefor the pharmaceutical industry and to determine the antioxidant metabolites against stress conditions. The effects of different stress treatments (media strength,macronutrient deficiency, oxidative, chemical, temperature and UV) on cardiotonic glycoside accumulation in D. lamarckii Ivanina, D. trojana Ivanina, D. davisiana Heywood and D. cariensis Boiss. ex Jaub. et Spach were investigated. HPLC analysis revealed that all stress conditions were significantly effective at 5% significance level according to their control groups. The predominant cardiac glycoside was lanatoside C (Lan C) followed by digitoxin, digoxigenin, gitoxigenin and digoxin. No digoxin was detected in all treatments as well as in control groups. Moreover, the effects of these stress treatments on the total phenolics, proline content and antioxidant enzymes activities were investigated. The results revealed that all stress conditions significantly increased the total phenolic and proline content. It was also concluded that CAT and SOD activities were markedly stimulated under all stress conditions in all Digitalis species, except for high temperature treatment. In contrast, high temperature stress resulted in lower CAT and SOD activities. All these results indicated that different stress treatments have induced changes in the redox state of callus cells and suggest that this alteration stimulates cardenolide formation in Digitalis callus cultures.