Optimization of Enzyme-Assisted Extraction from Ginger (Zingiber officinale) Leaf and Its Immune-Stimulating Effects on Macrophages.

The ginger leaves contain terpenoids and phenolic compounds, such as gingerol and shogaol, which exert various physiological effects. This study focused on determining the optimal conditions for an enzyme (Ultimase MFC) extraction to enhance the bioactive components of underutilized ginger leaves using the response surface method. The extracted material was evaluated in terms of its yield and antioxidant capacity (total phenolic content, total flavonoid content, and activities of 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid). As a result, the optimal conditions included an enzyme concentration of 0.1% (v/v), a liquid-solid ratio of 33.939 mL/g, and an extraction time of 4 h. The optimized conditions resulted in an improvement in yield and antioxidant capacity, except for the total phenolic content of ginger leaves, when compared to the reference control extract. Additionally, the possibility of improving immunity was confirmed as nitric oxide and cytokines increased in macrophage cells compared with non-treatment control. Therefore, these extraction conditions enhance the potential industrial value of ginger leaves and underscore their promise as a natural ingredient for functional foods.