Antibacterial activity of tea saponin from Camellia oleifera shell by novel extraction method

Abstract Natural preservatives are substances that are secreted by organisms or present in the body and have bacteriostatic effects, so they are not toxic to humans. Natural preservatives have become a research focus because of their high safety and strong antibacterial effects. Some commodities in the market are added with tea saponins, such as a brand of foaming cleanser, shampoo, and toothpaste rich in tea saponins. In this study, A high concentration of tea saponin was obtained through extraction and purification from Camellia oleifera shells, and its antibacterial activity for the two tested bacteria was determined in vitro. The results revealed that AB-8 macroporous adsorption resin was used in combination with Sephadex G-15 to obtain tea saponin with 82.5 % purity. The optimal purification process conditions were: the loading quantity of sample is 1 bed volume (BV), the loading solution is 25 mg/mL, the loading solution PH is 5, the loading flow rate is 3 BV/h, the elution volume is 4 BV, the elution flow rate is 3 BV/h, the eluent ethanol concentration is 95 %, and the eluent pH is 9. Tea saponin had good bacteriostatic effect on Escherichia coli and Staphylococcus aureus with its minimum inhibitory concentration of 1 and 0.5 mg/mL, respectively. In addition, its minimum bactericidal concentration was 4 mg/mL. Tea saponin could change membrane permeability, destroy cell membrane structure, and inhibit bacterial growth. This study provides basic guidance for the application of tea saponin in the development of natural antibacterial agents, is conducive to the high-value utilization of tea saponin, provides a reference for the economical of camellia tea waste, and plays a benefit in increasing agricultural income.