Chromatography of cardiac glycosides

Immunosensor for Rapid and Sensitive Detection of Digoxin

Digoxin is a cardiac glycosylated steroid-like drug with a positive inotropic effect and has been widely used in treating congestive heart failure, atrial fibrillation, atrial flutter, and other heart diseases. Digoxin is also a dangerous drug, which can cause drug poisoning at a low blood drug concentration (2.73-3.9 nmol/L, i.e., 2.14-3.05 ng/mL). Therefore, the timely detection of a patient's blood drug concentration plays a significant role in controlling blood drug concentration, reducing the occurrence of drug poisoning events, and maximizing the role of drug therapy. In this study, a DNA vector for the expression of the antidigoxin antibody Fab fragment was constructed. With the vector, Fab was expressed in E. coli and purified, and 1.2 mg of antibodies was obtained from 100 mL of culture. An immunofluorescent sensor based on the mechanism of photoinduced electron transfer was constructed by labeling additional cysteines in the heavy chain variable region and light chain variable region of the antibody Fab fragment with fluorescent dyes. The assay for digoxin with the immunosensor could be finished within 5 min with a limit of detection of 0.023 ng/mL, a detectable range of 0.023 ng/mL to 100 μg/mL, and an EC₅₀ of 0.256 ng/mL. A new approach for the rapid detection of digoxin was developed and will contribulte to therapeutic drug monitoring.

Cardenolides: Insights from chemical structure and pharmacological utility

Cardiac glycosides (CGs) are a class of naturally occurring steroid-like compounds, and members of this class have been in clinical use for more than 1500 years. They have been used in folk medicine as arrow poisons, abortifacients, heart tonics, emetics, and diuretics as well as in other applications. The major use of CGs today is based on their ability to inhibit the membrane-bound Na⁺/K⁺-ATPase enzyme, and they are regarded as an effective treatment for congestive heart failure (CHF), cardiac arrhythmia and atrial fibrillation. Furthermore, increasing evidence has indicated the potential cytotoxic effects of CGs against various types of cancer. In this review, we highlight some of the structural features of this class of natural products that are crucial for their efficacy, some methods of isolating these compounds from natural resources, and the structural elucidation tools that have been used. We also describe their physicochemical properties and several modern biotechnological approaches for preparing CGs that do not require plant sources.