Evaluation of synthesized magnetic nanoparticles and salicylic acid effects on improvement of antioxidant properties and essential oils of Calotropis procera hairy roots and seedlings

Abstract

Calotropis procera (Aiton) W.T.Aiton presents high levels of medicinally important terpenes and phenolics with antiinflammatory, antimicrobial, and antioxidant properties. The present study aimed to develop a suitable platform for mass production of pharmacological metabolites and improvement of antioxidant activity of C. procera. Motivated by such aim, potential effects of Fe3O4 nanoparticles (Fe3O4 NPs) and salicylic acid (SA) on antioxidant defense response and essential oils in seedlings and hairy roots were investigated. 21-day-old seedlings were treated by five levels of Fe3O4 NPs (0, 50, 100, 150, and 200 mg L−1) and three SA concentrations (0.0, 0.05, 0.1 mM). Moreover, the hairy roots about 2 cm were transferred into MS liquid medium supplemented with the above-mentioned concentrations of Fe3O4 NPs and 0 and 0.01 mM SA. After treatment, total phenolics, flavonoids, flavonol, anthocyanin, activity of polyphenol oxidase and l-phenylalanine ammonia-lyase, ferric-reducing antioxidant power, 2, 2‑diphenyl‑1‑picrylhydrazyl and production of essential oils were analyzed. Results demonstrated that hairy root culture is a powerful alternative for improving and inducing secondary metabolites of C. procera as compared to seedlings. Moreover, it was found that Fe3O4 NPs combined with SA have the more ability than all other treatments to improve antioxidant activity and essential oil in both seedlings and hairy roots. Here, 100 and 200 mg L−1 Fe3O4 NPs combined with 0.01 mM SA had more pronounced impact on induction of pharmacological constituents and antioxidant activity. Results suggest that Fe3O4 NPs and SA in hairy root culture can bring great insights into development in vitro biosynthesis of valuable secondary metabolites. Synthesized magnetic Fe3O4 nanoparticle combined with the salicylic acid in hairy root culture may be considered as a good alternative approach for the mass production of antioxidant and novel pharmacological metabolites of Calotropis procera.