Standardizing Medicinal Products with Convallaria majalis Cardiac Glycosides: The Prospect of Phasing out Biological Method

INTRODUCTION. The approved Russian regulations and guidelines on identification of medicinal products containing Convallaria majalis cardiac glycosides use group identification tests and thin-layer chromatography; spectrophotometry and bioassay are applied to quantify glycosides. Phasing out animal tests and lack of precision and reproducibility for bioassay methods necessitate the development of new physicochemical methods for the quality control of Convallaria majalis products.

AIM. This study aimed to replace in vivo assay of cardiac glycosides in Convallaria majalis medicinal products with physicochemical analysis.

MATERIALS AND METHODS. The study objects included Russian products: Convallaria tincture and Zelenin drops; Convallaria majalis extract reference standard, convallatoxin reference standard (93.0%). Biological activity was assessed on Rana ridibunda according to a compendial method. Convallatoxin content was determined using high-performance liquid chromatography (HPLC) within our method. Spearman’s rank correlation was assessed between the results of bioassay and HPLC/HPLC and spectrophotometry.

RESULTS. The study proved validity of an HPLC method for identification and quantitation of medicinal products containing Convallaria majalis cardiac glycosides. The content of convallatoxin, the predominant and most biologically active glycoside was determined by HPLC: Convallaria majalis extract standard reference — 0.14578 mg/mL; Convallaria majalis tincture — 0.01397 mg/mL; Zelenin drops — 0.00630 mg/mL; biological activity was determined as well. Spearman’s rank correlation of the findings was performed.

CONCLUSIONS. An HPLC-based method providing precise and reproducible results has been proposed for convallatoxin identification and quantitation in Convallaria tincture and Zelenin drops. Recommended convallatoxin content: Convallaria tincture 0.01–0.02 mg/mL; Zelenin drops 0.004–0.008 mg/mL.

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