Cardiotonic glycoside determination in in vitro and ex vitro samples of Digitalis lamarckii Ivan, an endemic species to Anatolia

Digitalis lamarckii Ivan is an endemic species to Turkey. Digitalis species are medicinally and economically important as they contain cardiac glycosides that strengthen diffusion and regulate the heart rhythm [1]. Moreover, preliminary studies have revealed that digoxin and digitoxin are also effective agents in several cancer treatments [2]. In this study cardenolide patterns in in vitro and ex vitro (from natural populations) samples of D. lamarckii were studied. In in vitro samples, digoxin was predominantly found in different tissues (lamina, petiole or whole shoot) of 12 or 18-week old regenerants. Digoxin content was, in general, lower in the 18-week old regenerants than 12-week old ones (Fig.1).

Fig.1: In vitro regenerant (12 weeks old) produced from 2.0mg/l BA+0.5mg/l NAA

Highest digoxin was, however, observed in lamina excised from 12-week old regenerants (130mg/kg). When varying concentrations of BA alone or in combination with NAA, BA at 1.0mg/l was found most productive (6.9mg digoxin/kg). For ex vitro, natural populations were studied with reference to different vegetation periods (June to September). Accumulation of digoxin, gitoxigenin, lanatoside C and digitoxin were estimated in leaf samples, and the higher amounts of digoxin were found in June samples extracted from mid-leaves (1010mg/kg) and reddish leaves collected in September (1062mg/kg). On the other hand, gitoxigenin, lanatoside C or digitoxin were found in trace amount.

Acknowledgements: The authors deeply appreciate the financial support of The Scientific and Technological Research Council of Turkey (TUBITAK) for the project TOVAG-106O470.

References: 1. Baytop T (1999). Therapy with medicinal plants in Turkey: Past and present. (2nd ed). Nobel kitabevi, Istanbul.

2. Newman et al. (2008). Cardiac glycosides as novel cancer therapeutic agents. Mol. Intv. 8(1): 36–49.