Effect of Ozone Treatment on the Contents of Selected Bioactive Phytochemicals in Leaves of Alligator Plant Kalanchoe daigremontiana

The study investigated the effect of ozone treatment applied to Kalanchoe daigremontiana plants on the contents of selected phytochemicals and on markers of oxidative stress in the leaves. For this purpose, alligator plants were exposed to the gaseous ozone applied at a rate of 5 and 10 ppm for 1, 5, and 10 min. Subsequently, tests were performed to assess the ozone-treated plants for the ability to produce reactive oxygen species (ROS), and for the activation of superoxide dismutase (SOD) and catalase (CAT), i.e., enzymes responsible for the decomposition of ROS. Measurements were also carried out to determine antioxidant potential, total contents of polyphenols, and vitamin C in plants as well as their mechanical properties. The findings show that the use of controlled conditions of ozone treatment (10 ppm; 1 min) resulted in increased contents of selected bioactive compounds (enhancement of total polyphenols 79%, enhancement of antioxidant potential ABTS 55.6% and DPPH 65.8%) in the ozone-treated raw material, with no phytotoxic effects of the process observed. It was shown that a short duration of ozone treatment is related to the increased activity of SOD (max 44%) and CAT (max 18.8%), which contributes to the lower production of ROS in cells of Kalanchoe daigremontiana.