Tea, the water extract of natural resources, is a traditional beverage expecting to provide various healthful benefits. To obtain expecting benefits from the tea, not only materials but the extraction method plays significant role. Due to complexity and diversity in effective component of those extracts, however, associated researches are limited. Here, we explored possible diversity in optimum conditions of tea extraction upon biological activities employing Jujube leaf. The jujube leaf is used as medicines and food ingredients in East Asia, but is normally abandoned as the waste of agricultural industry. Considering both healthful benefits and bio-industrial applications, we choose four useful biological activities possibly present in jujube leaf tea; anti-oxidant and inhibitory activities against alpha-amylase, alpha and beta-glucosidase. The optimum conditions of jujube leave tea extraction upon maximizing each biological activity were pursuit and compared employing response surface methodology. Three conditional factors including relative content of jujube leaf, temperature and time of extraction, were set as independent variables for deriving 15 extraction conditions based on preliminary experiments using Box-Benken design. Anti-oxidant property was measured by DPPH assay. And inhibitory effect of each enzyme was evaluated by employing enzyme activity assay based on Michaelis-Menten equation. As expected, the yield of extraction was increased as increase of those three variables. Temperature was the most significant factor but time was the least. Anti-oxidative effect follows the trends of extraction yield and the optimum condition was estimated as 70 °C, 31 min, 34 mg/mL of leaf for 74.91%. Amylase inhibition also follows the trends of extraction yield, but more sensitive on temperature. Maximum inhibitory effect on β-glucosidase could be achieved as 69% at 56 °C, 29 min, 34.91 mg/mL. IC50 of α-glucosidase can be maximized as 28 % (v/v) at 78 °C, 22 min, 31.79 mg/mL, but inhibitory effect could be increased via two processes; long time at low temperature and short time at high temperature. Based on our observation, the optimum condition for tea extraction should be diverse upon an objective bioactivity, and it is possible because tea extract should contain numerous phytochemicals and they should have synergetic effects.

Diversity in optimum conditions of tea extraction upon expecting biological activities

2019 Spring National Meeting

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