Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P47989 (xanthine oxidase)
 8,633 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The abilities of 15 flavonoids as a scavenger of active oxygens (hydroxyl radical and superoxide anion) were studied. Hydroxyl radical (.OH) was generated by the Fenton system, and assayed by the determination of methanesulfonic acid (MSA) formed from the reaction of dimethyl sulfoxide (DMSO) with .OH. (+)-Catechin, (-)-epicatechin, 7,8-dihydroxy flavone, and rutin showed the .OH scavenging effect 100-300 times superior to that of mannitol, a typical .OH scavenger. The other flavonoids showed no .OH scavenging effect at their concentrations up to 50 microM. Baicalein, quercetin, morin, and myricetin unexpectedly increased the .OH production in the Fenton system. The flavonoids tested now, except monohydroxy flavones, were more or less inhibitive to the superoxide anion (O2) generation in the hypoxanthine-xanthine oxidase system. A great part of this inhibitory effect was likely owing to suppression of xanthine oxidase activity by the flavonoids. The flavonoids, which scavenged .OH or O2-, were necessarily antioxidants to the peroxidation of methyl linoleate. However, there was a type of flavonoid such as morin, which have neither .OH nor O2- scavenging effect, but was a strong antioxidant.
 ...
PMID:The correlation between active oxygens scavenging and antioxidative effects of flavonoids. 807 Jun 90

The stems of Bougainvillea spectabillis Wild (Nyctaginaceae) have been used in folk medicine for hepatis, and spinasterol and quercetin were isolated and characterized from the plant leaves in this study. These constituents have not been previously isolated from Bougainvillea spectabillis W. Quercetin, the flavonoid, was found as active principle because it showed a strong activity on xanthine oxidase inhibition (IC50 = 7.23 microM) in this study as well as in the literature. Since xanthine oxidase serum levels are increased in hepatitis and tumoral brain tissues, quercetin may be used for remission of hepatitis or brain tumor. In order to study the structure-activity relationship of the flavonoids as regards xanthine oxidase inhibition, nine naturally occurring flavonoids have been tested the inhibitory effects on xanthine oxidase, such as baicalein, baicalin, capillarisin, d-catechin, d-epicatechin, hesperidin, liquiritin, puerarin and wogonin. The results showed that baicalein displayed the strongest activity (IC50 = 9.44 microM), followed by wogonin (IC50 = 52.46 microM) and then baicalin (IC50 = 71.73 microns). Baicalein induced uncompetitive inhibition of the enzyme with respect to xanhtine and the apparent inhibition constant (Ki) was 2.48 x 10(-6) M.
 ...
PMID:Inhibitory effects of flavonoids on xanthine oxidase. 829 30

Baicalein (5,6,7-trihydroxy-2-phenyl-4H-1-benzopyran-4-one), a naturally occurring flavonoid, was found to prevent human dermal fibroblast cell damage induced by reactive oxygen species such as hydrogen peroxide (H2O2), tert-butyl hydroperoxide (BuOOH) and superoxide anions (.O2-) in a concentration-dependent manner, and was more effective than the iron chelator, deferoxamine, hydroxyl radical (.OH) scavengers such as dimethyl sulfoxide (DMSO) and ethanol (EtOH), the lipid peroxidation chain blocker, alpha-tocopherol (Vit. E) and the xanthine oxidase inhibitor, allopurinol. To probe the mechanism of cell defense, the reaction of baicalein with oxygen free radicals was investigated using electron spin resonance (ESR) spectrometry. Baicalein decreased the signal intensities due to the 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) spin adducts of .OH, .O2- and tert-butyl peroxyl (BuOO.) radicals in a concentration-dependent manner. The IC50 values, which are the 50% inhibition concentrations of baicalein for the free radicals, were 10, 45 and 310 microM, respectively. These results suggested that baicalein possesses free radical scavenging ability which prevents the fibroblast damage induced by these free radical species.
 ...
PMID:Protective effects of baicalein against cell damage by reactive oxygen species. 977 34

Xanthine oxidase inhibitors are known to be therapeutically useful for the treatment of hepatitis and brain tumor. Baicalein, baicalin and wogonin, isolated from Scutellaria rivularis, have been reported to exhibit a strong activity on xanthine oxidase inhibition. In this study, their antioxidant activity was evaluated by modified xanthine oxidase inhibition and cytochrome c reduced methods. The results showed that the order of activity on xanthine oxidase inhibition was baicalein > wogonin > baicalin, IC50 = 3.12, 157.38 and 215.19 microM, respectively, whereas the activity on cytochrome c reduction was baicalin > wogonin > baicalein (IC50 = 224.12, 300.10 and 370.33 microM, respectively). In another study, an electron spin resonance (ESR) technique was used to further confirm the direct free radical scavenging activity. Both baicalein and baicalin demonstrated a strong activity on eliminating the superoxide radical (.O2-) (baicalein: 7.31 x 10(4) u/g; baicalin: 1.19 x 10(5) u/g). The IC50 of baicalein was 2.8 fold higher than that of baicalin. However they had no significant effect on scavenging hydroxyl radical (.OH). The present results demonstrated that baicalein and baicalin posed a different pathological pathway. The antioxidant function of baicalin was mainly based on scavenging superoxide radical whilst baicalein was a good xanthine oxidase inhibitor.
 ...
PMID:Antioxidant and free radical scavenging effects of baicalein, baicalin and wogonin. 1106 94

The dried roots of Scutellaria baicalensis (S. baicalensis) Georgi (common name: Huangqin in China) have been widely employed for many centuries in traditional Chinese herbal medicine as popular antibacterial and antiviral agents. They are effective against staphylococci, cholera, dysentery, pneumococci and influenza virus. Baicalein, one of the major flavonoids contained in the dried roots, possesses a multitude of pharmacological activities. The glycoside of baicalein, baicalin is a potent anti-inflammatory and anti-tumor agent. This review describes the biological properties of baicalein (Table 1), which are associated with the prevention and treatment of cardiovascular diseases. Baicalein is a potent free radical scavenger and xanthine oxidase inhibitor, thus improving endothelial function and conferring cardiovascular protective actions against oxidative stress-induced cell injury. Baicalein lowers blood pressure in renin-dependent hypertension and the in vivo hypotensive effect may be partly attributed to its inhibition of lipoxygenase, resulting in reduced biosynthesis and release of arachidonic acid-derived vasoconstrictor products. On the other hand, baicalein enhances vasoconstricting sensitivity to receptor-dependent agonists such as noradrenaline, phenylephrine, serotonin, U46619 and vasopressin in isolated rat arteries. The in vitro effect is likely caused by inhibition of an endothelial nitric oxide-dependent mechanism. The anti-thrombotic, anti-proliferative and anti-mitogenic effects of the roots of S. baicalensis and baicalein are also reported. Baicalein inhibits thrombin-induced production of plasminogen activator inhibitor-1, and interleukin-1beta- and tumor necrosis factor-alpha-induced adhesion molecule expression in cultured human umbilical vein endothelial cells. The pharmacological findings have highlighted the therapeutic potentials of using plant-derived baicalein and its analogs for the treatment of arteriosclerosis and hypertension.
 ...
PMID:Biological properties of baicalein in cardiovascular system. 1585 50