Quercetin-induced benzophenanthridine alkaloid production in suspension cell cultures of Sanguinaria canadensis.

Addition of micromolar concentrations of quercetin or rutin to suspension cell cultures of Sanguinaria canadensis L. (bloodroot) induced the biosynthesis of sanguinarine and chelerythrine in a dose-dependent manner. In contrast, related compounds: baicalein, naringin, naringenin, catechin, caffeic acid and benzoic acid displayed very weak inductive activity. Of the two active flavonoids, quercetin was the most effective for inducing benzophenanthridine alkaloid biosynthesis, with doses of 100 microM increasing alkaloid production over 375% as compared to negative controls. Quercetin's inductive effects were similar to that of an elicitor derived from fungus Penicillium expansum (PE-elicitor). Suppression of quercetin and PE-induced alkaloid biosynthesis by low doses of actinomycin D (5 micrograms/ml, alpha-amanitin (20 micrograms/ml), or cycloheximide (1 microgram/ml) demonstrate a requirement for both RNA and de novo cytoplasmic protein synthesis and suggest that alterations in gene expression are involved in the inductive mechanism. Furthermore, quercetin-induced alkaloid biosynthesis was significantly reduced by pretreatment of the cells with the calcium chelator, EGTA (3 mM), or the calcium channel inhibitor, verapamil (100 microM), suggesting that this process was calcium dependent.