Rosmarinic acid content and antioxidant capacity in Dracocephalum moldavica hairy roots affected by iron and copper nanoparticles

Abstract

The present study aimed to develop a protocol for hairy root induction from Dracocephalum moldavica leaf explants and evaluate the effects of iron nanoparticles (Fe NPs) (0, 250, 500 and 1000 ppm), copper nanoparticles (Cu NPs) (0, 25, 50 and 100 ppm) and the combination of both (Fe/Cu NPs) on antioxidant capacity, phenolic, flavonoids and rosmarinic acid content of hairy roots. Hairy root induction in D. moldavica was significantly (P ≤ 0.01) influenced by Agrobacterium rhizogenes strains, culture media and sucrose concentration. The highest hairy root induction (86/6%) was related to ATCC15834 strain on Murashige and Skoog culture medium supplemented with 30 g l− 1 sucrose. The individual and combined effect of Fe and Cu NPs on the measured traits was highly significant (P ≤ 0.01). The highest amount of rosmarinic acid (26.38 mg/g DW) was obtained in Cu NPs (100 ppm) with Fe NPs (1000 ppm) treatment that was 6.6-fold higher compared to control. The highest amount of flavonoids, malondialdehyde (MDA), phenolic compounds, hydrogen peroxide (H2O2), proline, and anthocyanin production was obtained in Cu NPs (100 ppm) + Fe NPs (1000 ppm) treatment that was 1.86, 1.56, 1.76, 2.07, 1.62 and 1.65-fold higher compared to respective control. Correlation and principal component analysis revealed a clear separation between treatments groups and control also a positive correlation among rosmarinic acid production and other traits. The findings of this study indicated the best results were obtained with the combined effect of Cu NPs (100 ppm) with Fe NPs (1000 ppm) treatment.