Quaternary alkaloids in Chelidonium majus in vitro cultures

Abstract

Chelidonium majus L. is a medicinal plant containing several alkaloids, such as chelidonine, chelerythrine, sanguinarine, protopine, and coptisine that are stored and secreted from laticifers—highly specialized elongated cells of aerial and terrestrial parts of the plant. For use as a drug, several cultivars of this specialized crop are cultivated but the content and composition of bioactive substances is variable. Based on the observation of a characteristic orange-yellow color of latex in dedifferentiated tissue of in vitro callus cultures we investigated the alkaloid composition and the anatomy of callus and organ cultures of C. majus maintained on media enriched in plant growth regulators and illuminated with white or photosynthetically active light. Alkaloid composition was analyzed using DAD-HPLC, whereas tissue and organ anatomy was studied using light and scanning electron microscopy.The fully developed organs and rhizogenic callus compared to the undifferentiated cells, produced larger proportion of alkaloids, and complex alkaloid composition. In roots, sanguinarine was the predominant alkaloid exceeding 4 mg/g dry mass. In microshoots, coptisine was the major compound, with the maximum content exceeding 14 mg/g, depending on the medium composition. In callus cultures, either protopine or sanguinarine predominated on different media and under different illumination, with maximum content over 13 mg/g dry mass of protopine reached under PAR (Photosynthetically Active Radiation), and sanguinarine over 0.9 mg/g. The presence of laticifers was confirmed with microscopy and the scanning electron microscopy revealed an abundant extracellular matrix in the callus tissues.These results suggest the high biosynthetic potential of in vitro grown organs and dedifferentiated callus tissue that are able to produce significant amounts of pharmacologically relevant alkaloids from C. majus in various proportions that depend on the culture conditions such as supplementation with growth substances and sugars as well as on the illumination with light of different spectrum.