Icariside II

Peroxisome proliferator-activated receptor α and-γ (PPARα/γ) are known to play crucial roles in acute liver injury (ALI). Icariside II (ICS II), a natural flavonoid compound derived from Herba EpimedII, confers neuroprotection with PPARα/γ induction potency.

This study was aimed to explore whether ICS II has the capacity to protect against ALI, and the role of PPARα/γ in the beneficial effect of ICS II on ALI.

Mice challenged by D-galactosamine (GalN)/lipopolysaccharide (LPS) and Kupffer cells (KCs) upon LPS insult were used as ALI models in vivo and in vitro. PPARα/γ-deficient mice were treated with ICS II to validate the potential targets of ICS II on ALI.

We found that ICS II (5, 10, 20 mg/kg) dose-dependently improved the survival rate and liver histology, decreased ALT and AST in GalN/LPS-treated mice. Furthermore, ICS II directly bound to PPARα/γ and increased their activities. The protective properties of ICS II were counteracted when PPARα/γ were knocked out in GalN/LPS-induced mice and LPS-induced KCs, respectively. Mechanistically, ICS II restored mitochondrial function, reduced oxidative stress and inflammation through activating PPARα/γ, which activated Sirt6 and inhibited NF-κB nuclear translocation.

Our findings not only highlight PPARα/γ-SIRT6 signaling as a vital therapeutic target to combat ALI, but also reveal ICS II may serve as a novel dual PPARα/γ agonist to safeguard ALI from the oxidation-inflammation vicious circle by mediating SIRT6/NF-κB.

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 Epimedium was 16.9%. The enzyme, which was produced from Aspergillus 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^oC and 5.0. The purified enzyme hydrolyzed the 7-O-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-Oxyloside 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^oC 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 Epimedium extract using a non-GMO, crude enzyme from Aspergillus sp.y48. The obtained icariside II and the byproduct icaritin can be directly applied in the production of cosmetics and pharmaceuticals.