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At least 793 records · Page 44Linked to original sources
PubMed1993

Purification of an UDP-glucose:flavone, 7-O-glucosyltransferase, from Silene latifolia using a specific interaction between the enzyme and phenyl-Sepharose.

An UDP-glucose:flavonoid, 7-O-glucosyltransferase, from Silene latifolia was isolated from petals and purified 450-fold using a combination of gel-filtration, affinity chromatography and anion-exchange chromatography. Affinity chromatography on a phenyl-Sepharose CL-4B column in combination with elution with the substrate, isovitexin (6-C-glucosylapigenin), was an especially effective purification step. A purification factor between 10 and 20 could be reached using this column. A possible mechanism for the specific interaction of the enzyme with the phenyl-Sepharose will be discussed. This method of purification may also be applicable to other enzymes which use aromatic compounds as substrates. On a SDS-PAGE gel a band of 54 kDa, which co-purified with enzyme activity, could be detected in the purest fraction.

Chromatography, Affinity↗
PubMed2006

The anti-inflammatory flavones quercetin and kaempferol cause inhibition of inducible nitric oxide synthase, cyclooxygenase-2 and reactive C-protein, and down-regulation of the nuclear factor kappaB pathway in Chang Liver cells.

We examined the ability of the flavonoids quercetin and kaempferol to modulate inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and reactive C-protein (CRP) expression, and to induce changes in the nuclear factor kappa B (NF-kappaB) pathway in the human hepatocyte-derived cell line Chang Liver. Cells were incubated with a cytokine mixture supplemented with quercetin or kaempferol (5 to 200 micromol/l). Kaempferol produced a significant concentration-dependent decrease of iNOS, COX-2 and CRP protein level at all concentrations, but the percentage of inhibition induced by quercetin was reduced at high concentrations. Both flavonoids significantly inhibited mRNA level of iNOS, COX-2, and CRP. Inhibitory effects by quercetin and kaempferol were also observed on NF-kappaB activation and on protein concentration of the phosphorylated form of the inhibitor IkappaB alpha and of IKK (IkappaB kinase)alpha. The present study suggests that the modulation of iNOS, COX-2 and CRP by quercetin or kaempferol may contribute to the anti-inflammatory effects of these two structurally similar flavonoids in Chang Liver cells, via mechanisms likely to involve blockade of NF-kappaB activation and the resultant up-regulation of the pro-inflammatory genes. Our data also indicate that the minor structural differences between both compounds determine differences in their inhibitory capacity.

C-Reactive Protein↗
PubMed2003

Immunosuppressive flavones and lignans from Bupleurum scorzonerifolium.

Two lignans, isochaihulactone and chaihunaphthone, together with eleven known compounds were isolated from the root of Bupleurum scorzonerifolium. Their structures were established on the basis of spectral evidence. In biological testing, eugenin and saikochromone potently inhibited CD28-costimulated activation of human peripheral blood T cells.

Antineoplastic Agents, Phytogenic↗
PubMed2004

Three acylated flavone glycosides from Sideritis ozturkii Aytac & Aksoy.

From the aerial parts of Sideritis ozturkii, three new flavonoids, chrysoeriol 7-O-[2'''-O-caffeoyl-O-acetyl-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside], chrysoeriol 7-O[2'''-O-caffeoyl-beta-D-glucopyranosyl-(1 -->2)-beta-D-glucopyranoside] and chrysoeriol 7-O[2'''-O-p-coumaroyl-6'''-beta-O-acetyl-D-glucopyranosyl-(1-->2)-beta-D-glucopyranoside] named as ozturkosides A, B and C, respectively, were isolated, along with three known phenylethanoid glycosides, verbascoside, leucoseptoside A, martynoside and five known diterpenoids, 7-epicandicandiol, linearol, sidol, sideroxol, epoxyisolinearol. The structures were elucidated mainly by spectroscopic methods.

Chromatography, Liquid↗
PubMed2005

Suppression of cyclooxygenase-2 expression of skin fibroblasts by wogonin, a plant flavone from Scutellaria radix.

Previously, wogonin (5,7-dihydroxy-8-methoxyflavone) was found to suppress proinflammatory enzyme expression including cyclooxygenase-2 (COX-2), contributing to in vivo anti-inflammatory activity against skin inflammation. However, the detailed effect on each skin cell type has not been understood. Therefore, present investigation was carried out to find the effect of wogonin on inflammation associated gene expression from skin fibroblasts in culture using reverse transcriptase-polymerase chain reaction. As a result, it was found that wogonin (10-100 microM) clearly down-regulated COX-2 expression from NIH/3T3 cells treated with 12-O-tetradecanoylphorbol 13-acetate, interleukin-1beta or tumor necrosis factor-alpha. But, the expression levels of COX-1, interleukin-1beta and fibronectin were not significantly affected. This finding was well correlated with significant reduction of prostaglandin E2 (PGE2) production by wogonin. As a comparison, NS-398 (selective cyclooxygenase 2 inhibitor) did not suppress COX-2 expression and other gene levels, while PGE2 production was potently reduced at 0.1-10 microM. All these results suggest that COX-2 down-regulation of skin fibroblasts may be, at least in part, one of anti-inflammatory mechanisms of wogonin against skin inflammation.

Animals↗
PubMed2003

Effects of wogonin, a plant flavone from Scutellaria radix, on skin inflammation: in vivo regulation of inflammation-associated gene expression.

Flavonoids from plant origin show anti-inflammatory activity in vitro and in vivo. In addition to inhibition of inflammation-associated enzymes, such as cyclooxygenases (COX) and lipoxygenases, they have been found to regulate the expression of inflammation-associated proteins from in vitro experiments. In order to prove in vivo behavior and the potential for beneficial use against inflammatory skin disorders, the effect of wogonin (5,7-dihydroxy-8-methoxyflavone) on in vivo expression of several inflammation-associated genes was examined in the intact as well as in the inflamed mouse skin by reverse transcriptase-polymerase chain reaction analysis. When applied topically on the intact skin, only a high dose treatment of wogonin (1000 microg/ear/3 days) slightly increased COX-1 and fibronectin mRNA. On the other hand, wogonin at the doses of 250-1000 microg/ear/3 days potently lowered mRNA levels of COX-2 and tumor necrosis factor-alpha with less effect on intercellular adhesion molecule-1 and interleukin-1beta in a sub-chronic skin inflammation model of tetradecanoylphorbol-13-acetate-induced ear edema (multiple treatment). The decrease of prostaglandin E(2) concentration (27.3-34.3%) was concomitantly observed in the wogonin-treated groups. A similar effect was also observed in an acute inflammation model of arachidonic acid-induced ear edema. From the present study, wogonin was proved to differentially regulate the expression of inflammation-associated genes in vivo and to become a useful therapeutic agent for skin inflammatory diseases mainly due to its modulation of the expression of proinflammatory molecules.

Animals↗
PubMed1999

Oxygen activation during peroxidase catalysed metabolism of flavones or flavanones.

Flavonoids containing phenol B rings, e.g. naringenin, naringin, hesperetin and apigenin, formed prooxidant metabolites that oxidised NADH upon oxidation by peroxidase/H2O2. Extensive oxygen uptake occurred which was proportional to the NADH oxidised and was increased up to twofold by superoxide dismutase. Only catalytic amounts of flavonoids and H2O2 were required indicating a redox cycling mechanism that activates oxygen and generates H2O2. NADH also prevented the oxidative destruction of flavonoids by peroxidase/H2O2 until the NADH was depleted. These results suggest that prooxidant phenoxyl radicals formed by these flavonoids cooxidise NADH to form NAD radicals which then activated oxygen. Similar oxygen activation mechanisms by other phenoxyl radicals have been implicated in the initiation of atherosclerosis and carcinogenesis by xenobiotic phenolic metabolites. This is the first time that a group of flavonoids have been identified as prooxidants independent of transition metal catalysed autoxidation reactions.

Catalysis↗