Impact of Green Synthesis of Silver Nanoparticles on Antioxidant Activity in Drought-Sensitive and Drought-Tolerant Pimpinella anisum L.

The rapid advancement and evolution of nanotechnology have raised concerns about the potential release of nanoparticles (NPs) into the environment. Since plants are vital components of ecosystems, they play a crucial role in interacting with these substances. This study is the first to investigate how green-labeled silver nanoparticles (AgNPs) affect the activity of three key antioxidant enzymes: catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (GPOx), in anise (Pimpinella anisum L.). Two varieties of anise were examined: drought-sensitive (DS) and drought-tolerant (DT). These plants were exposed to varying concentrations of AgNPs (1, 5, and 10 mg/L) for 21 and 28 days. The results showed no significant difference in CAT activity across all AgNP concentrations for both cultivars. However, SOD activity increased significantly in DT plants treated with 5 mg/L AgNPs for 21 days. In contrast, SOD activity at other concentrations and exposure durations did not yield statistically significant results. For GPOx activity, DT plants exhibited a significant increase after 21 days at both 1 mg/L and 5 mg/L AgNPs. Results at other concentrations varied and were not statistically significant according to the exposure duration and plant variety. Overall, this study suggests that the increased enzyme activity at low AgNP concentrations in DT plants after 21 days indicates an acceptable, harmless level of toxicity. These findings underscore the complexity of AgNP effects on antioxidant enzyme activity in anise plants, highlighting the need for further investigation into the underlying mechanisms and long-term effects of AgNP exposure on plant antioxidant defense systems.