Physicochemical properties of dihydromyricetin and the effects of ascorbic acid on its stability and bioavailability

Dihydromyricetin (DMY) is a natural dihydroflavonol with many bioactive effects. However, the physicochemical properties of DMY related to its bioavailability, especially its stability, are unclear.

The effects of pH, temperature, metal ions and ascorbic acid (AA) on the stability of DMY were studied using high-performance liquid chromatography (HPLC). The bioavailability of DMY in the presence and absence of AA was compared. Dihydromyricetin was unstable in weak alkaline solutions, and the degradation was significantly accelerated in the presence of Cu²⁺ and Fe³⁺ . The degradation process followed the first-order kinetic model. The degradation rate constant (k) increased with increasing pH and temperature. The remaining DMY was only 49% of its initial concnentration after 4 h in simulated intestinal fluid (SIF) at 37 °C. However, by supplementing with AA, the degradation of DMY was rarely occured within 6 h. The solubility of DMY at pH 3-5 was about 750 μg mL^-1 , slightly increasing to 853 μg mL^-1 at pH 6. Pharmacokinetic studies showed that the bioavailability of DMY increased from 0.122% to 0.341% by supplementing with AA (10% of DMY).

The degradation of DMY is one reason for its poor bioavailability. The presence of AA could significantly improve the stability of DMY, and further improve its bioavailability in rats. © 2020 Society of Chemical Industry.