The Effect of Iron Oxide Nano-Particles on the Production of Tropane Alkaloids, h6h gene Expression and Antioxidant Enzyme Activity in Atropa belladonna Hairy Roots

Atropa belladonna L. from the Solanaceae family is one of the major commercial sources of tropane alkaloids such as atropine and scopolamine. These types of alkaloids are more often used as anti-spasmodic, anti-cholinergic, sedative, analgesic, and dilatation of the pupil. The effect of different iron oxide nano-particles concentrations (0, 250, 500, 750, and 1000 mg/L) with two exposure time (24 and 48 hours) on total phenol and flavonoid content, antioxidant enzymes activity, tropane alkaloids content (atropine and scopolamine), and hyoscyamine 6β-hydroxylase ( h6h ) gene expression level were evaluated. The results of ANOVA analysis revealed that the antioxidant enzymes, including catalase, guaiacol peroxidase and ascorbate peroxidase activity was significantly enhanced in induced samples compared to control treatments. The highest amounts of phenol (4.05 mg gallic acid per gram fresh weight) and flavonoid (2.66 mg quercetin per gram fresh weight) were obtained in hairy roots elicited with 250 mg/L elicitor. The maximum content of atropine (345.74 μg/g dry weight, about 34.6-fold compared to the control) and scopolamine (979.45 μg/g dry weight, about 51.5-fold compared to the control) were recorded in hairy roots treated with 250 and 1000 mg/L iron oxide nano-particles during 48-hourexposure time, respectively. The semi-quantitative RT-PCR analysis declared that the highest h6h expression in hairy roots stimulated with 750 mg/L iron oxide for 48 hours. Based on these results, it can be concluded that iron oxide nano-particles may be used as an effective stimulant for the production of tropane alkaloids due to the stimulation effects on the expression of h6h gene.