Quantitative evaluation of cardiac glycosides and their seasonal variation analysis in Nerium oleander using UHPLC-ESI-MS/MS

Introduction Nerium oleander is an eminent source of structurally diverse cardiac glycosides (CGs), plays a prominent role in the treatment of heart failure, and inhibits the proliferation of cancer cell lines. CGs exert their cardiotonic action by binding to the extracellularly exposed recognition sites on Na+/K+-ATPase, an integral membrane protein that establishes the electrochemical gradient of Na+ and K+ ions across the plasma membrane. Objective We aimed to quantitatively determine CGs and their seasonal variation in leaf and stem samples of N. oleander utilizing UHPLC-ESI-MS/MS techniques. Methods The UHPLC-ESI-MS/MS analytical method was developed utilizing multiple reaction monitoring (MRM) mode. The Waters BEH C18 (150 mm x 2.1 mm, 1.7 mu m) column was used with a 22-min linear gradient consisting of acetonitrile and 5 mM ammonium acetate buffer. Results In total 21 CGs were quantitatively determined in the seasonal leaf and stem samples of N. oleander along with the absolute quantitation of the three chemical markers odoroside H (244.8 mu g/g), odoroside A (231.4 mu g/g), and oleandrin (703.9 mu g/g). The season-specific accumulation of chemical markers was observed in the order of predominance odoroside A (summer season, stem), odoroside H (winter season, stem), and oleandrin (rainy season, leaf). Besides this, the remaining 18 CGs were relatively quantified in the same samples. Conclusion The developed method is simple and reliable and can be used for the identification and quantification of multiple CGs in N. oleander.

Automated summary

In this study, UHPLC-ESI-MS/MS techniques were used to quantitatively determine cardiac glycosides (CGs) and their seasonal variation in leaf and stem samples of Nerium oleander. A total of 21 CGs were quantitatively determined, including three chemical markers: odoroside H (244.8 μg/g), odoroside A (231.4 μg/g), and oleandrin (703.9 μg/g). The season-specific accumulation of these chemical markers was observed. Additionally, the remaining 18 CGs were relatively quantified in the same samples. The developed method is simple and reliable for the identification and quantification of multiple CGs in N. oleander.