Effect of pH extraction buffer on antioxidant enzymes activities in water lily’s leaves and petioles

Water lily (Nymphaea antares) is one of the most valuable aquatic ornamental plants which has bright potential in the floriculture industry. It may be useful as an urban ecosystem and as a source of medicinal compounds. Due to its potential to become a new value-added product in the food industry, water lily (N. antares) was investigated in this study. Therefore, the goal of this study was to determine the nutritional content and antioxidant activity in water lily leaves and petioles with different pH extraction buffers. Water lily extract was obtained using three different pH extraction buffers, Tris buffer at pH 6.8, pH 7.1 and pH 7.8. The heat capacity of the extract was analysed using differential scanning calorimetry (DSC) and different functional groups were identified using Fourier transform infrared spectroscopy (FTIR). Thermal denaturation of the leaves sample was detected at 81.84°C. The antioxidant enzymes activities including catalase (CAT), peroxidase (POX), polyphenol oxidase (PPO), and superoxide dismutase (SOD) were determined in the leaves and petioles of water lily. In leaves, PPO activity was found to be higher in samples with pH 7.1 of the extraction buffer while there were no significant differences for activities of CAT, POX and SOD in all samples. In petioles, PPO and POX activity were found to be higher in samples with pH 7.8 and 7.1 of extraction buffer, respectively. Thus, the study found that a pH range of 7 to 9 extraction buffers did not greatly affect most of the analysis performed.