Effect of the green synthesized rGO and Mg/rGO nanocomposites on the phytochemical assay, toxicity, and metabolism of Mentha longifolia in vitro cultures

Reduced graphene oxide (rGO) and Mg/rGO nanocomposites (NCs) were prepared by an eco-friendly technique using Rosa canina fruit extract. Physicochemical properties and cytotoxicity to Mentha longifolia in vitro cultures of these nanomaterials were examined by using XRD, FESEM, EDX, FT-IR, DLS/zeta potential, UV-Visible, and GC-MS techniques. The characterization techniques confirmed the synthesis of rGO and Mg/rGO NCs with particle sizes less than 20 nm (based on FESEM). In accordance to the biological measurements, rGO showed in vitro cytotoxicity to M. longifolia shoot cultures. Mg/rGO NCs showed no significant difference in the growth parameters except for a decrease in the shoot number at the concentrations of 50 and 150 mg/L and a decrease in the length of the tallest root at the concentrations of 100 and 150 mg/L, however efficiently improved the photosynthetic pigment contents. The phytochemical assay depicted that the total content of volatile compounds was increased in the treated cultures with 25, 50, and 100 mg/L of rGO and Mg/rGO NCs in comparison to the control. Generally, the more oxygenated and hydrocarbon sesquiterpenes were observed in the cultures treated with 25 and 100 mg/L of rGO and 25 and 50 mg/L of Mg/rGO NCs.