Stimulation of tanshinone production in Salvia miltiorrhiza hairy roots by β-cyclodextrin-coated silver nanoparticles

Diterpenoid tanshinones, major bioactive constituents of Salvia miltiorrhiza roots are drug candidates against cardiocerebral diseases. To develop sustainable and effective elicitation strategies for the enhanced production of tanshinones, the spherical shaped beta-cyclodextrin-coated silver nanoparticles (AgNP-beta-CDs, empty set35.3 8.3 nm) were synthesized and applied as elicitor to hairy root cultures of S. miltiorrhiza. The content of total tanshinones including tanshinone I, IIA and cryptotanshinone in the cultures was stimulated by AgNP beta- CD at 30 mg/L. The elicitation effects of AgNP-beta-CD on tanshinone were found to be related to the released dissolved Ag+ and nanoparticle bumping to the root surface in the cultures. AgNP-beta-CD treatment induced reactive oxygen species (ROS) including H2O2 and O-2(-) production in the hairy roots, leading to enhance activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), and up-regulated expressions of key biosynthetic genes for tanshinones in hairy roots. The nano-elicitor increased total production of tanshinones in 18-day-old hairy root cultures to 10.8 mg/L, a 1.8-fold over that of the control. These results indicate that AgNP- beta-CD could be a novel effective elicitor in hairy root cultures for the production of pharmaceutical secondary metabolites.