Chitosan nanoparticles as elicitors of phenolic compounds in cell cultures of Dracocephalum polychaetum Boiss.: A dose-dependent in vitro study

Chitosan nanoparticles (CNPs) are considered promising elicitors for enhancing secondary metabolite production under in vitro conditions. In the present study, CNPs were applied at different concentrations (0, 10, 25, 50, 100, and 150 ppm) to cell suspension cultures of Dracocephalum polychaetum Boiss. to assess physiological changes and secondary metabolite responses. Notably, treatments with 10 and 25 ppm CNPs significantly enhanced the accumulation of phenolic compounds, including chlorogenic acid (up to 13.25 µg g⁻¹ FW), catechin (up to 247.45 µg g⁻¹ FW), and quercetin (up to 1837.28 µg g⁻¹ FW). In contrast, higher concentrations of CNPs led to significant increases in MDA and H₂O₂ levels. Correlation analysis indicated that MDA content was negatively correlated with most measured parameters. A strong negative association was observed between oxidative biomarkers and phytochemical compounds, whereas specialized metabolites showed positive interrelations among themselves. Overall, the results demonstrated that low to moderate doses of CNPs effectively activated the phenylpropanoid pathway, leading to enhanced accumulation of phenolic and flavonoid compounds in D. polychaetum without causing cellular damage. This study represents a promising biocompatible elicitor for controlled metabolite production under in vitro conditions and may provide a strategy for metabolite production in valuable medicinal plants. • Dracocephalum polychaetum is a medicinal herb with valuable phenolic compounds. • Low and moderate chitosan nanoparticle enhanced phytochemical accumulation in D. polychaetum . • High concentrations of chitosan nanoparticle increased oxidative stress indicators (MDA, H₂O₂). • Chitosan nanoparticle elicitation is a scalable, eco- friendly method for enhancing the valuable metabolites.