Enzymatic Activity Assays for P. notoginseng

The SOD (superoxide dismutase) activity of the P. notoginseng leaves was quantified using a WST-8 assay kit (Suzhou Keming Biotechnology Co., Ltd.) following previous reports (Cao et al., 2022 (link)). In brief, 0.1 g of leaves and 1 mL of extraction solution are ground into homogenate on ice, and then centrifuged at 8000 g and 4°C for 10 min, taking the supernatant as the extract. After treatment, the extract was incubated with reaction solution for 30 min at 25 °C. The absorbance at a wavelength of 450 nm was measured with an enzyme-labeled instrument (Molecular Devices, Sunnyvale, CA, United States). Another assay kit (Nanjing Jiancheng Bioengineering Institute, Nanjing, China) was used to measure the POD (peroxidase) enzyme activity of P. notoginseng leaves (Hu et al., 2022 (link)). Briefly, 0.1 g of leaves and 0.9 mL physiological saline solution were homogenized and centrifuged for 10 min at 4°C and 8000 g. The enzyme activity was measured by taking the supernatants and determining its absorbance at the wavelength of 470 nm on enzyme-labeled instrument.