Extraction, Purification, Selenocarbamate Derivatization, and Biological Activities of Tea Saponins From Camellia Oleifera Cake

ABSTRACT With the increasing planting area of Camellia oleifera worldwide, its by‐products, Camellia oleifera cake, have also accumulated and increased, causing environmental pollution and resource waste. This work studied the extraction of tea saponin from Camellia oleifera cake by methanol/water method and optimized its process conditions. Single factor experiments and response surface experiments were carried out to determine the optimal process conditions for extracting tea saponins: methanol concentration of 75.7%, liquid‐to‐solid ratio of 16:1 (mL/mg), extraction temperature of 41.5°C, and extraction time of 3.3 h. The maximum effective extraction rate of tea saponins (TS) was 13.6%. Compared with the traditional ethanol–water system, the methanol–water system had the advantages of easy recovery of the extractant, low energy consumption, low cost, high product content, and light color. The crude tea saponins were separated by semi‐preparative high‐performance liquid chromatography, and two TS monomers TS1 and TS2 with a purity of over 98% were obtained. Fifteen Selenocarbamate derivatives of TS were obtained by reacting TS with selenium isocyanates. Biological activity tests showed that the antibacterial activity of TS monomers was significantly better than that of crude TS. The antioxidant activity of Selenocarbamate derivatives of TS is significantly better than that of TS.