0.45 m multiscreen filter plate

Biological triplicates were prepared from the first pair of true leaves of individual plants grown in separate pots. Leaves of D. lanata and D. purpurea were freeze-dried for 24 hours using a Labconco FreeZone 2.5 lyophilizer (Kansas, Missouri, USA). The samples were then homogenized using polypropylene pellet pestles (DWK life sciences, NJ, USA) in 1.5 ml tubes. 100 µL of 80% methanol was used to resuspend per mg of dry tissue at room temperature. The samples were vortexed and incubated at 65 ˚C for 10 min. The extract was then centrifuged at 18,000 g for 10 minutes and the supernatant was filtered through a 0.45 µm multiscreen filter plate (Merck Millipore, Carrigtwohill, Ireland). The samples were stored at -20 ˚C before LC/MS analysis.

The leaf samples for HRLC/MS analysis were freeze-dried for 24 hours using a Lab-conco FreeZone 2.5 lyophilizer (Kansas, Missouri). The dry weights of samples were recorded. The samples were then homogenized using plastic pestles (DWK life sciences, New Jersey) and dissolved in 1 ml of 80% methanol with vortexing. The samples were then incubated at 65 °C for 10 min. The internal standard, digoxin-d3, was added at a final concentration of 50 nM to the extracts. The samples were then centrifuged at 18,000xg for 2 min, and the supernatant was filtered through a 0.45 µm multiscreen filter plate (Merck Millipore, Carrigtwohill, Ireland) . The samples were stored at -20 °C until HRLC/MS analysis.