Quercetin-3-O-glucose-6''-acetate

J Food Sci. 2011 Aug;76(6):C869-73.

Flavonol content in the water extract of the mulberry (Morus alba L.) leaf and their antioxidant capacities.[Pubmed: 22417484]

The biological activities of the mulberry (Morus alba L.) leaf have been attributed to its flavonoid content.
METHODS AND RESULTS:
The water extract of the mulberry leaf (WEML) was prepared by autoclaving at 121 °C for 15 min, and the flavonol content of the WEML was determined by HPLC The WEML contained 4 flavonols in the following order: quercetin-3-β-D-glucose (QT-G) > quercetin-3-O-glucose-6″-acetate (QT-GA) > rutin (RT) > quercetin (QT). In the oxygen radical absorbance capacity (ORAC) assay, QT had the highest peroxyl radical-scavenging capacity and a similar hydroxyl radical-scavenging capacity as its glycosides (QT-G, QT-GA, and RT).
CONCLUSIONS:
QT exhibited a stronger cellular antioxidant capacity (CAC) against 2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH)- and Cu²⁺-induced oxidative stress in HepG2 cells compared to its glycosides, indicating that the intracellular antioxidant capacity of QT and its glycosides may depend upon both the permeability across the cell membrane and the peroxyl or hydroxyl radical-scavenging capacity.

Mol Cell Biochem. 2011 Jun;352(1-2):91-8.

A Drosophila model for the screening of bioavailable NADPH oxidase inhibitors and antioxidants.[Pubmed: 21312054]

NADPH oxidase is the major source of non-mitochondrial cellular reactive oxygen species (ROS), and also is reported to be a major cause of various diseases including atherosclerosis and hypertension.
METHODS AND RESULTS:
In order to screen a new curative reagent that can suppress NADPH oxidase activity, we developed a Drosophila melanogaster fly that would overexpress human Dual oxidase 2 (hDuox2), a member of the NADPH oxidase family, as a screening model. These flies (GMR-GAL4/UAS-hDuox2) had a high generation of ROS in the posterior region of the eye discs along with an easily recognizable rough-eye phenotype, which is an ideal and convenient marker for further screening steps. Moreover, the hDuox2-induced rough-eye phenotype can be rescued by feeding with a culture medium containing mulberry leaves (MLs), which reportedly have an antimetabolic effect. Some commercially available antioxidants such as quercetin-3-O-D-glucoside or Quercetin-3-O-glucose-6''-acetate, or the naringin contained in MLs and other herbs, also have shown a similar suppressing effect on the rough-eye phenotype.
METHODS AND RESULTS:
Our results suggest that flavonoid glycoside is absorbed from the intestine and functions in the body of D. melanogaster as it does in mammalian models such as rats. Thus, the GMR-GAL4/UAS-hDuox2 fly line is a promising model for the screening of novel drugs such as NADPH oxidase inhibitors and/or antioxidants.