Silver nanoparticles (AgNPs) are widely used in many applications of biotechnology, including medicine and agriculture. They are released to the nature as waste materials, which can cause physiological and biochemical effects on plants. Indigo, indirubin and tryptanthrin are valuable indole alkaloid compounds in Isatis constricta due to both medicinal effects and dye properties. This research was conducted to determine the effects of different concentrations (0, 0.25, 0.5, 1, 1.5 and 2 mg L-1) of AgNPs on the production of indigo, indirubin and tryptanthrin compounds in leaves of in vitro grown shoots of I. constricta Davis. Indigo production was 1.15-fold of control (869 +/- 8.33 mu g g(-1)) in the leaves of shoots regenerated in Murashige and Skoog supplemented with 2 mg L-1 of AgNPs (1003 +/- 11.42 mu g g(-1)) on 5 days post-treatment. Tryptanthrin production showed an increase in all applications of AgNPs, but the highest increase was observed at a concentration of 2 mg L-1 (4.59 +/- 0.046 mu g g(-1)) and this increase was 1.71-fold of control (2.68 +/- 0.031 mu g g(-1)) on 5 days post-treatment. The production of indigo and tryptanthrin decreased on 10 and 15 days post-treatment with AgNPs. The contents of indirubin decreased during day 5-10-15 and at all concentrations of AgNPs compared to the control
