Biologically synthesized CuO nanoparticles induce physiological, metabolic, and molecular changes in the hazel cell cultures.

The utilization of plant extracts in nanoparticle (NP) synthesis has been suggested as a nature-friendly method and an efficient alternative to the conventional approaches such as physical and chemical methods. Taxol is a valuable medicinal compound, and hazelnut has been suggested as one of the sustainable resources for producing this metabolite. In the present research, copper oxide (CuO) nanoparticles (NPs) were biologically synthesized by utilizing hazelnut leaf extracts. FTIR, XRD, EDAX, DLS, and SEM analyses were used for characterizing and confirming the synthesized NPs. The effect of biosynthesized CuO NPs (10 and 90 ppm), para-aminobenzoic acid (PABA) (20 ppm), and CuSO4 (10 ppm) on the cell viability, biochemical properties, expression of TAT and GGPPS genes, and accumulation of taxol and baccatin III in hazelnut cell cultures was investigated. The results indicated that biosynthesized CuO NPs significantly influenced the cell viability, amount of ROS, antioxidant capacity, lipid peroxidation, secondary metabolite production, and expression pattern of the genes engaged in the biosynthesis pathway of taxanes in the C. avellana L. cells. The cytotoxicity of CuO NPs to cells was dose dependent and increased with increasing its concentration, as evidenced by a decline in the survival rate and cell membrane integrity. Furthermore, the utilization of 10 ppm CuSO4 caused more toxicity in the cells than the same concentration of CuO NPs. This result could be attributed to the fact that plant extracts components act as a coating for the NPs and reduce their toxicity. Treatment of the cell cultures with CuO (10 ppm) + PABA (20 ppm) and CuO (10 ppm) induced the highest radical scavenging activity. The activity of antioxidant enzymes was increased with increasing the copper oxide NPs level from 10 to 90 ppm. Contrariwise, the cell's survival rate, radical scavenging activity, and amount of secondary metabolites were significantly reduced in the higher levels of copper oxide NPs (90 ppm) compared to the 10 ppm. The combined utilization of 10 ppm copper oxide NPs and 20 ppm PABA considerably stimulated the TAT and GGPPS genes expression and produced the highest amount of taxol and baccatin III. KEY POINTS: • CuO NPs were biologically synthesized using the hazel leaf extracts and confirmed by FTIR, XRD, EDAX, DLS, and SEM analyses. • CuO NPs significantly affected the amount of ROS, antioxidant capacity, and lipid peroxidation in C. avellana L. cells. • Treatment of the hazel cells with CuO NPs increased the production of secondary metabolites including taxol and baccatin III and expression of the genes involved in taxol and baccatin III biosynthesis (TAT and GGPPS).