Total Synthesis of Quercetin 3-Sophorotrioside

Synthesis of Quercetin 3-O-[6″-O-(trans-p-Coumaroyl)] …
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This report describes the efficient synthesis of quercetin 3-O- ..

The lipid droplets and TG levels were lower in theberberine, high- and medium-dose quercetin groups compared to themodel group that used ORO staining and ORO-based colorimetricquantitative assay. This finding suggested that-quercetinsignificantly improved hepatic lipid accumulation. Hepatic lipidaccumulation is involved in various pathways, such as thesynthesis, transport and oxidation of long-chain fatty acids andTG. When the amount of intake and synthesis of fatty acid surpassesits outtake and catabolism, the lipid is expected to be depositedin the liver cells potentially resulting in a fatty liver (). To further investigate the mechanismof quercetin on the hepatic lipid accumulation amelioration, keyfactors of fatty acid synthesis and metabolism were determinedusing semi-quantitative RT-PCR and western blot analysis. A majorcause of steatosis is the increased fatty acid flux to the liverdue to a high availability of plasma FFA with regard to peripheraloxidative requirements. SREBP-1c and FAS are known to be involvedin fatty acid synthesis (). Theupregulated SREBP-1c and FAS levels in the model group indicatedthat SREBP-1c and FAS are involved in the development andpathogenesis of NAFLD with steatosis and IR. After treatment withquercetin, the expression of SREBP-1c and FAS was inhibited,showing that quercetin improved hepatic lipid accumulation byaffecting fatty acid synthesis mediated by the inhibition ofSREBP-1c and FAS expression.

Total synthesis of phenylpropanoid glycosides, ..
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The Stereoselective Total Synthesis of ..

To elucidate the suppressive effects of hyperin and quercetin on oxidative stress and melanin synthesis, peroxynitrite (ONOO) scavenging activity was measured as were quantifications of melanin content, intracellular total RS, ONOO, superoxide (O2), nitric oxide (NO), catalase activity and the reduced glutathione (GSH)/oxidized glutathione (GSSG) ratio.

Synthesis of quercetin 5-O-β-d-glucoside 13 and ..
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(4) The flavonoid account for more than 1% of total flavonoid in onion were quercetin-3-O-β-glucoside, 7-O-β-glucoside, 7, 4'-diO-β-glucoside and isorhamnetin-4'-O-β-glucoside.

Schematic representation of the synthesis of Cu–quercetin complex
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An expeditious synthesis of quercetin ..

AB - Quercetin has been shown to act as a hyperthermia sensitizer by inhibiting the synthesis of heat shock protein 70 (HSP70) in a variety of tumour cell lines. It is most effective under conditions of low pH. This study was designed to test the hypothesis that quercetin suppresses thermotolerance development in cells adapted to growth at low pH and renders them as responsive as acutely acidified cells to hyperthermia-induced cytotoxicity. Chinese hamster ovarian carcinoma cells (OvCa) were exposed to 42°C hyperthermia and/or quercetin (50-200 μm) at their growth pH of either 7.3 or 6.7 or after acute acidification from 7.3 to 6.7. Thermotolerance development was measured by colony survival. HSP70 synthesis and total protein synthesis were measured by radioactive precursor pulse labelling techniques. Quercetin, in a concentration-dependent manner, reduced the rate of total protein synthesis and increased cytotoxicity equally after acute acidification to pH 6.7 or growth at pH 6.7 at 37°C, and to a greater extent than it did in cells at pH 7.3. At 42°C, 100 μm quercetin inhibited total protein synthesis, HSP70 synthesis and thermotolerance development to a similar extent in cells grown at pH 6.7 or acutely acidified to pH 6.7. In contrast, quercetin reduced but did not completely inhibit HSP70 synthesis and thermotolerance development in cells grown and heated at pH 7.3. These results support the hypothesis that quercetin can specifically reduce thermotolerance development in tumour cells adapted to growth at pHe 6.7 so that they respond similarly to acutely acidified cells. Since many tumours are adapted to growth at low pH and may resist a wide variety of therapeutic modalities, inhibition of thermotolerance expression by quercetin may not only enhance the response to hyperthermia but the response to commonly used therapies such as chemotherapy and radiation.

Total Synthesis of Brevetoxin-B ..

Quercetin is one of the most studied flavonoids. Itis present in several fruits, vegetables, nuts and seeds mainly asglycoside and, thus, is a main component of the daily human diet(). Quercetin is known to protectcells from oxidative stress and it has also been shown to modifyeicosanoid biosynthesis, prevent platelet aggregation, protectlow-density lipoprotein from oxidation and promote relaxation ofcardiovascular smooth muscle ().The anti-oxidant activity of quercetin has often been suggested tobe associated with a pharmacological function in the cardiovascularsystem (). The aim of this studywas to investigate the effect of quercetin on NAFLD. Consequently,the effects of quercetin on FFA-induced steatosis andinsulin-induced IR in HepG2 cells as well as the underlyingmechanism of action were examined. The characteristics of the cellmodel used were consistent with the pathogenesis characteristics ofNAFLD, a fact facilitating the investigation of potential effectivetherapies for NAFLD.