(-)-Dihydroquercetin

Brain Res., 2003, 965(1-2):130-6.

Neuroprotective effects of antioxidative flavonoids, quercetin, (+)-dihydroquercetin and quercetin 3-methyl ether, isolated from Opuntia ficus-indica var. saboten.[Pubmed: 12591129]

The flavonoids quercetin, (+)-dihydroquercetin, and quercetin 3-methyl ether were isolated from the ethyl acetate fractions of the fruits and stems of Opuntia ficus-indica var. saboten.
METHODS AND RESULTS:
In the present study, we evaluated their protective effects against oxidative neuronal injuries induced in primary cultured rat cortical cells and their antioxidant activities by using three different cell-free bioassays. Quercetin was found to inhibit H(2)O(2)- or xanthine (X)/xanthine oxidase (XO)-induced oxidative neuronal cell injury, with an estimated IC(50) of 4-5 micro g/ml. However, it was no more protective at concentrations of 30 micro g/ml and above. (+)-Dihydroquercetin concentration-dependently inhibited oxidative neuronal injuries, but it was less potent than quercetin. On the other hand, quercetin 3-methyl ether potently and dramatically inhibited H(2)O(2)- and X/XO-induced neuronal injuries, with IC(50) values of 0.6 and 0.7 micro g/ml, respectively. All three principles markedly inhibited lipid peroxidation and scavenged 1,1-diphenyl-2-picrylhydrazyl free radicals. In addition, quercetin and quercetin 3-methyl ether were shown to inhibit XO activity in vitro, with respective IC(50) values of 10.67 and 42.01 micro g/ml.
CONCLUSIONS:
These results indicate that quercetin, (+)-dihydroquercetin, and quercetin 3-methyl ether are the active antioxidant principles in the fruits and stems of Opuntia ficus-indica var. saboten exhibiting neuroprotective actions against the oxidative injuries induced in cortical cell cultures. Furthermore, quercetin 3-methyl ether appears to be the most potent neuroprotectant of the three flavonoids isolated from this plant.

Int. J.Toxicol., 2015, 34(2): 243-310.

Toxicological and Genotoxicity Assessment of a Dihydroquercetin-Rich Dahurian Larch Tree (Larix gmelinii Rupr) Extract (Lavitol).[Pubmed: 25850419 ]

Safety assessment is reported of an orally ingested dihydroquercetin-rich extract (Lavitol) derived from the Dahurian larch tree, used as a food additive and as a dietary supplement ingredient.
METHODS AND RESULTS:
Dihydroquercetin, a potent antioxidant, is also known as taxifolin. The results of genotoxicity and toxicological tests (Comet assay, micronucleus test in human lymphocytes, chromosomal aberration test, subacute 7-day oral toxicity study, subchronic 90-day toxicology study with histopathologies, and, prenatal and postnatal developmental toxicity studies) on the extract provide further support for the safety of its consumption as a food supplement and food additive.