3-methylquercetin

Quercetin 3-O-methyl ether is a potent phosphodiesterase (PDE)3/4 inhibitor, it has potential for treating asthma against ovalbumin-induced airway hyperresponsiveness.

3-O-Methylquercetin is a selective and competitive PDE3 PDE4 inhibitor, and inhibits PDE3 than PDE4 with a low K(m) value; it inhibits total cAMP- and cGMP-phosphodiesterase (PDE) of guinea pig trachealis at low concentrations.

3-O-Methylquercetin 4',7-di-β-D-glucopyranoside, a flavonoside, is isolated from *Ophioglossum pedunculosum* [1].

Isorhamnetin (3-methylquercetin) is the methylated metabolite of quercetin. Quercetin is an important dietary flavonoid with in vitro antioxidant activity. Isorhamnetin prevents endothelial cell injuries from oxidized LDL via inhibition of lectin-like ox-LDL receptor-1 upregulation, interference of ox-LDL-mediated intracellular signaling pathway (p38MAPK activation, NF-kappaB nuclear translocation, eNOS expression) and the antioxidant activity of isorhamnetin. Isorhamnetin prevents endothelial dysfunction, superoxide production, and overexpression of p47phox induced by angiotensin II. Isorhamnetin appears to be a potent drug against esophageal cancer due to it's in vitro potential to not only inhibit proliferation but also induce apoptosis of Eca-109 cells.

Neochilenin (3-O-Methylquercetin 4'-O-glucoside) is a glycoside derivative of 3-O-methylquercetin that is extractable from the sub-family Cereoideae of the Cactaceae family. [1]