Recrystallization of dihydromyricetin from Ampelopsis grossedentata and its anti-oxidant activity evaluation.

A fast and efficient method for purification of dihydromyricetin (3,5,7,3',4',5'-six hydroxy-2,3-dihydro flavonol; DMY) from Ampelopsis grossedentata was created by crystallization eight times at 25°C, and a purity of 98% was finally achieved. The purified DMY exhibited high oxygen radical absorbance capacity (ORAC) (30.21 μmol Trolox equiv/mg) and strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (half-maximal inhibitory concentration [IC50]=0.235 μg/mL). The addition of DMY could also effectively attenuate 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH)-induced human erythrocyte hemolysis and cupric chloride (CuCl2)-induced human plasma lipid peroxidation via inhibition of intracellular reactive oxygen species (ROS) generation. It was also found that DMY (>12 μg/mL) treatment significantly inhibited intracellular malondialdehyde (MDA) formation. Meanwhile, DMY treatment significantly inhibited the obvious increase of anti-oxidant enzymes levels (superoxide dismutase [SOD]; glutathione peroxidase [GPX], and catalase [CAT]) induced by AAPH radicals, suggesting that stress defense mechanisms are associated with protection of DMY against intracellular oxidation.