Effect of three kinds of nanoparticles and methyl jasmonate on antioxidant system activity in Cannabis sativa L.

Introduction
Cannabis sativa L. is an annual dioecious plant from Central Asia. It has been used since ancient times as a medicinal plant, but also it is the source of hemp fibers and of a vegetable oil used as food. Cannabis has been used for medicinal purposes, for treating pain, spasms, asthma, insomnia, depression, and loss of appetite, in many cultures for hundreds of years. Antioxidants are the most important chemical compounds found in the C. sativa species. Cannabis contains a diverse group of active compounds, including cannabinoids, terpenes, and flavonoids, which exhibit multidirectional biological activity and can influence each other’s pharmacological profile. Hemp leaves, often considered waste in the industry, have been found to contain high levels of active compounds, making them a valuable resource for extraction. Utilizing hemp leaves can contribute to a zero-waste approach and sustainable development of the industry. Considering the climatic diversity of Iran, as well as the importance of the medicinal plant cannabis and also the use of nanoparticles in agriculture, the present study was conducted with the aim of the effect of these abiotic elicitors on the antioxidant system of cannabis.
Materials and Methods
In order to evaluate the effect of nanoparticles of titanium dioxide (TiO2) (250 and 500 mg/l), zinc dioxide (ZnO2) (125 and 250 mg/l), cerium dioxide (CeO2) (125 and 250 mg/l) and methyl jasmonate (MJ) (50 and 100 μM) on the antioxidant activity of hemp plant, a factorial experiment was conducted based on a completely randomized design with three replications. The elicitors solution was applied as irrigation and the sampling of plant leaves was done 24, 48 and 72 hours after elicitors treatment, respectively. After preparing the enzyme extracts from the leaf tissue of treated cannabis plants, the activity of antioxidant enzymes catalase, ascorbate peroxidase, superoxide dismutase, glutathione reductase and guaiacol peroxidase was measured using a spectrophotometer.
Results and Discussion
The analysis of variance results indicated the significance (p≤0.01) of the effect of different elicitors and sampling times on all antioxidant activities. Also, all the two-way elicitor × time interaction effects were significant (p≤ 0.01) on all studied traits. In means comparison of the two-way interaction effect, it was found that the 125 mg/l of CeO2 and 250 mg/l of ZnO2 in the sample taken 48 hours after the treatment had the highest amount of protein. Also, 250 mg/l TiO2 in 48 hours sampling after the treatment showed the highest amount of catalase, 125 mg/l ZnO2 in the 72 and 48 hours sampling after the treatment showed the highest amount of ascorbate peroxidase, the 250 mg/l CeO2 in 48 hours sampling after the treatment showed the highest amount of glutathione reductase, the 125 mg/l CeO2 in 48 hours sampling and 250 mg/l ZnO2 in 72 hours sampling showed the highest levels of guaiacol peroxidase, and 50 µM methyl jasmonate in the sample taken 48 hours after the treatment had the highest amount of superoxide dismutase in the leaves of the hemp plant.
Conclusion
In this research, the highest amount of protein was observed with cerium and zinc nanoparticles at 48 hours sampling time after treatment. Also, the highest amount of catalase with titanium nanoparticles at 48 hours, the highest amount of ascorbate peroxidase with zinc nanoparticles at 72 and 48 hours, the highest amount of glutathione reductase and Guaiacol peroxidase with cerium nanoparticles in 48 hours and the highest amount of superoxide dismutase with methyl jasmonate in 48 hours sampling time after treatment were observed in hemp leaves.