Impacts of manganese bio-based nanocomposites on phytochemical classification, growth and physiological responses of Hypericum perforatum L. shoot cultures.

We report a new green route for preparing MnO2/perlite nanocomposites (NCs) by leaf extract of Hypericum perforatum. Characterization of the physicochemical properties of the MnO2/perlite-NCs was performed using XRD, FESEM, EDX, FT-IR, and DLS techniques. Furthermore, their effects on the phytochemical classification and growth parameters of H. perforatum shoot cultures were assessed. According to the FESEM image, the synthesized spherical MnO2 nanoparticles on the sheet-like structure of nano-perlite were formed, ranging about 20-50 nm. In addition, based on the EDX spectra, the elemental analysis showed the presence of Carbon, Oxygen, Silicon, Aluminum, and Manganese elements in the as-synthesized MnO2/perlite-NCs. Biological studies confirmed that nano-perlite and MnO2/perlite-NCs were non-toxic to H. perforatum shoot cultures and showed positive effects on plant growth in specific concentrations. Overall, phytochemical classification demonstrated that the terpenoids decreased in the evaluated treatments, while hypericin and pseudohypericin were increased in some treatments (25, 50 and 150 mg/L of nano-perlite) relative to control. Metabolomics results suggested that both nano-perlite and MnO2/perlite-NCs can be used as elicitors and new nanofertilizers for generating some secondary metabolites.

Effect of explant source, perlite nanoparticles and TiO2/perlite nanocomposites on phytochemical composition of metabolites in callus cultures of Hypericum perforatum.

It appears that the biologically-synthesized nanoparticles (NPs) have potential to perform as effective elicitors for the production of valuable secondary metabolites in plants. Besides, it has been reported that the toxicity of the biologically-synthesized NP is not as much as that of the chemically-synthesized NPs. Therefore, it is necessary to test their advantages aspects. In this study, the physical synthesis of perlite NPs and biologically-synthesis of TiO2/perlite nanocomposites (NCs) were conducted. Subsequently, their effects and explant source influence on the growth characteristics and secondary metabolite profiles of Hypericum perforatum callus cultures were evaluated. According to the obtained results, morphology of the synthesized perlite NPs and TiO2/perlite NCs were mesoporous and spherical with sizes ranging about 14.51-23.34 and 15.50-24.61 nm, respectively. Addition of perlite NPs and TiO2/perlite NCs to the culture medium at the concentration range of 25-200 mg/L showed no adverse impacts on the growth characteristics of H. perforatum calli. According to the GC-MS analysis, the stress caused by perlite NPs and TiO2/perlite NCs led to an increase in the variety, amount and number of volatile compounds. The calli obtained from in vitro grown plants produced more volatile compounds relative to the calli obtained from field grown plants under the nanomaterial stress conditions. The production of hypericin and pseudohypericin were also determined in the callus cultures under desired nanomaterials elicitation. Accordingly, our results suggest that perlite NPs and TiO2/perlite NCs can possibly be considered as effective elicitors for the production of volatile compounds, hypericin, and pseudohypericin in callus cultures of H. perforatum.