Icariside II Preparation from Icariin Separated from <i>Epimedium</i> Herbal Extract Powder by a Special Icariin Glycosidase

In this study, icariside II was prepared from icariin by a special enzyme. The yield of the substrate icariin from a powdered extract of the popular herb <i>Epimedium</i> was 16.9%. The enzyme, which was produced from <i>Aspergillus</i> sp.y48 fermentation, hydrolyzes icariin to icariside II and was characterized. The molecular weight was 75 kDa, while the optimum temperature and pH were 45°C and 5.0. The purified enzyme hydrolyzed the 7-<i>O</i>-glucoside of icariin or epimedin A, B, and C to icariside II, or sagittatoside A, B, and C, respectively, and further hydrolyzed the terminal 3-<i>O</i>-xyloside of sagittatoside B to icariside II. The enzyme is a special icariin glycosidase that hydrolyzed icariin to icariside II at low cost. Based on the crude enzyme's reaction dynamics, the optimal conditions for icariside II preparation showed that 2% icariin reacted at 45°C for 6 to 9 h. Here, we obtained 13.3 g icariside II and 0.45 g of the by-product icaritin from 20 g icariin. The icariside II molar yield was 87.4%, the by-product icaritin yield was 4.1%, and the total molar yield was 91.5%. Therefore, icariside II was resoundingly prepared from an icariin glycosidase of an <i>Epimedium</i> extract using a non-GMO, crude enzyme from <i>Aspergillus</i> sp.y48. The obtained icariside II and the by-product icaritin can be directly applied in the production of cosmetics and pharmaceuticals.