Applicability of high-performance liquid chromatography to the analysis of cardiac glycosides in lily-of-the-valley medicines (review)

Introduction. The standardisation of lily-of-the-valley (Convallaria majalis) herbal drugs containing cardiac glycosides of the cardenolide group currently uses either animal bioassays or spectrophotometry. The need to explore the possibility of abandoning animal testing makes it essential to find a selective and sensitive physicochemical method for the determination of cardiac glycosides in lily of the valley.

Aim. This study aimed to select an appropriate alternative to animal testing through a comparative analysis of scientific publications on physicochemical methods for the determination of cardenolide cardiac glycosides.

Discussion. According to the analysis of identification and quantification methods for cardenolides, animal testing does not provide sufficient accuracy and reproducibility for the standardisation of herbal drugs, herbal drug preparations, and herbal medicinal products. However, spectrophotometry does not provide sufficient specificity, and thin-layer chromatography is mainly applicable to the identification of cardenolides. This article presents the results of comparing the chromatographic conditions used for cardenolide determination by high-performance liquid chromatography (HPLC) with various detectors. According to the study results, HPLC can replace animal bioassays or insufficiently selective methods in the determination of cardiac glycosides in lily-of-the-valley products. The development of analytical procedures for cardenolide determination can be based upon reverse-phase HPLC with octadecylsilyl (С18) as the stationary phase, a solvent mixture comprising water, acetonitrile, and/or methanol in different proportions as the mobile phase, and a diode-array detector at 220 ± 2 nm.

Conclusions. The results of this comparative analysis indicate that the method for the identification and quantification of cardiac glycosides in lily-of-the-valley herbal drugs, herbal drug preparations, and herbal medicinal products is promising for further study and experimentation. HPLC is applicable for routine use and can replace animal bioassays or insufficiently selective methods in the determination of lily-of-the-valley cardiac glycosides.