Highest Quercetin Content Research Articles

Quercetin regulates Th1/Th2 balance in a murine model of asthma

Quercetin is found to be the most active of the flavonoids in studies and many medicinal plants owe much of their activity to their high Quercetin content. Quercetin has demonstrated significant anti-inflammatory activity because of direct inhibition of several initial processes of inflammation. However, its anti-allergic effect in the Th1/Th2 immune response was poorly understood. Recently, it was shown that T-bet and GATA-3 were master Th1 and Th2 regulatory transcription factors. In this study, we have attempted to determine whether Quercetin regulates Th1/Th2 cytokine production, T-bet and GATA-3 gene expression in OVA-induced asthma model mice. Quercetin reduced the increased levels of IL-4, Th2 cytokine production in OVA-sensitized and -challenged mice. The other side, it increased IFN-γ, Th1 cytokine production in Quercetin administrated mice. We also examined to ascertain whether Quercetin could influence Eosinophil peroxidase (EPO) activity. The administration of Quercetin before the last airway OVA challenge resulted in a significant inhibition of all asthmatic reactions. Accordingly, this study may provide evidence that Quercetin plays a critical role in the amelioration of the pathogenetic process of asthma in mice. These findings provide new insight into the immunopharmacological role of Quercetin in terms of its effects in a murine model of asthma, and also broaden current perspectives in our understanding of the immunopharmacological functions of Quercetin.

Antioxidant activity and phenolic composition of herbhoneys

A study of 10 herbhoneys of various origin revealed differences in their antioxidant activity and profiles of phenolic acids and flavonoids. The total phenolic content of herbhoneys determined spectrophotometrically varied between 21.7 and 75.3 mg gallic acid equivalents per 100 g product, and the total flavonoid content ranged from 6.9 to 28.5 mg quercetin equivalents per 100 g. Dark herbhoneys, such as raspberry, thyme, hawthorn and black chokeberry, exhibited a high antioxidant activity and contained high total levels of polyphenols and flavonoids. There was a significant linear correlation between total phenolic and flavonoid contents and antioxidant activity in the reactions with DPPH and ABTS + free radicals. The profiles of phenolic acids and flavonoids determined by HPLC depended on the variety of herbhoney. Among the products studied, raspberry and thyme herbhoneys were the richest in phenolic acids and flavonoids. The dominant phenolic acid in most samples was p-coumaric acid; the herbhoneys contained also a considerable amount of gentisic acid. The dominant flavonoids were hesperetin and naringenin. Thyme herbhoney had an especially high quercetin content.

Quercetin and rutin contents in Siamese neem flower extracts prepared by different extraction methods

Siamese neem tree (Azadirachta indica A. Juss. var. siamensis Valeton) is a medicinal plant found in every part of Thailand. The young flowers of this plant are commonly consumed with sweet sauce as a bitter tonic vegetable for elemental tonic purpose [1]. The flower extract has been reported to exhibit in vitro free radical scavenging activity and inhibit lipid peroxidation of bronchogenic cancer cell line [2]. Active components in Siamese neem flowers are flavonoids such as quercetin and rutin. The content of these compounds in the crude extract is depended on the method of extraction. This work investigated the quantity of rutin and quercetin in the flower extracts of Siamese neem tree prepared by several extracting methods using high performance liquid chromatography (HPLC) to find the appropriate extraction method which gives the maximum contents of rutin and quercetin. The flowers were extracted using maceration, percolation, decoction, soxhlet extraction, ultrasonic extraction (UE) and microwave assisted extraction methods. The solvent used in maceration, percolation and soxhlet extraction was 50% ethanol, in decoction and MA was distilled water, while in UE was both 50% ethanol and distilled water. By HPLC, the results showed that soxhlet extraction method gave the extract containing the maximum contents of rutin and quercetin (10.21 and 0.12% w/w of the extract, respectively). Quercetin was detected only in the extract prepared using 50% ethanol as the solvent. Thus, soxhlet extraction should be the appropriate extraction method for Siamese neem flowers to yield the extract with high contents of active components, rutin and quercetin.

Alpinia zerumbet Potentially Elevates High-Density Lipoprotein Cholesterol Level in Hamsters

In folkloric plant medicines, Alpinia zerumbet (AZ) has been popularly recognized as an exellent hepatoprotector. To search for a good high-density lipoprotein cholesterol (HDL-C) elevating herbal preparation, we examined AZ for its antioxidant and hypolipidaemic bioactivities, especially its HDL-C elevating activity. AZ seeds contain 0.51% essential oils (SO), which are comprised of monoterpenoids, oxygenated monoterpenoids, sesquiterpenoids, oxygenated sesquiterpenoids, aldehydes, acid, and esters. Gas chromatography/mass spectrometry analysis indicated that most of the monoterpenes and sesquiterpenes were recoverable in pentane eluent, whilst the oxygenated monoterpenoids and sesquiterpenoids remained in ether eluent. The high contents of rutin, quercetin, and polyphenolics in ethanolic extract of AZ seeds exhibit moderate antilipoperoxidative but potent DPPH free radical scavenging bioactivities. Conclusively, both seed powder (SP) and SO are effective hypolipidaemics with amazingly potent HDL-C elevating capabilities. On the basis of hepatoprotectivity, SP is a more feasible hypolipidemic agent as well as a promising HDL-C elevating plant medicine.

Supplementary Ultraviolet Radiation B Together with Blue Light at Night Increased Quercetin Content and Flavonol Synthase Gene Expression in Leaf Lettuce (Lactuca sativa L.)

Establishment of an effective supplementary lighting procedure is necessary to increase the value of leaf lettuce grown using a hydroponic method involving a low production cost. In leaf lettuce extracts, quercetin, one of the flavonoids, was isolated and identified. It was investigated that quercetin has important functions that can be used as a dietary supplement. Flavonol synthase (FLS) is a key enzyme involved in quercetin biosynthesis, catalyzes the conversion of dihydroquercetin to quercetin. Therefore, we determined the sequence of the flavonol synthase gene (FLS) in red leaf lettuce. We harvested leaf lettuce grown using supplementary light sources, such as ultraviolet radiation B (UV-B), ultraviolet radiation A, blue, and red lamps during the night. It is noteworthy that FLS expression and the quercetin content were particularly increased to a greater extent in young leaves than in mature leaves when UV-B and blue light were used simultaneously at night. We suggest that UV-B with blue light is used simultaneously at night for producing leaf lettuce with high quercetin content.

Protective effects of ethanolic extracts of buckwheat groats on DNA damage caused by hydroxyl radicals

Buckwheat, including common buckwheat (Fagopyrum esculentum Moehch) and tartary buckwheat (Fagopyrum Tartaricum Gaerth), is widely cultivated in the northwest part of China and its groats is rich in antioxidant compounds. In order to understand its antioxidant activity, the protective effects of the ethanolic extracts from four buckwheat groats on DNA damage caused by hydroxyl radical are examined by two different methods, and the reducing power, chelating activity, and total phenolic contents are also determined. The results show that the buckwheat ethanol extracts (BEE) possess strong capability to protect DNA from being damaged by hydroxyl radical, which may be attributed to their chelating activity on iron and hydroxyl radical scavenging activity. Among the four buckwheat samples, ethanol extracts from two tartary buckwheat samples show that its DNA protective ability is higher than that from two common buckwheat samples because of their high rutin, quercetin and phenolic content.

Effect of Pectolytic Enzyme Preparations on the Phenolic Composition and Antioxidant Activity of Asparagus Juice

Commercial pectolytic enzymes were investigated for their influence on phenolics and antioxidant activities of asparagus juice. The antioxidant activity of asparagus juice was analyzed according to 2,2'-diphenyl-l-picrylhydrazyl and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) methods. The enzymes, with the exception of pectinase from Rhizopus sp., contained rutinase, which hydrolyzed rutin to quercetin. Asparagus juice treated with Viscozyme had the highest quercetin content without exhibiting a significant increase in the antioxidant activity. For a pectinase from Aspergillus niger, the antioxidant activity of asparagus juice was markedly reduced. Caution should be paid in the selection of pectolytic enzyme preparations for production of antioxidant activity-rich juice.

Direct HPLC analysis of quercetin and trans-resveratrol in red wine, grape, and winemaking byproducts.

A simple and fast reversed-phase HPLC method using diode array detection was developed and validated for the simultaneous determination of trans-resveratrol and quercetin in Sicilian red wine from the Nero d'Avola red grape variety. Investigation was also extended to the quantitative determination of resveratrol and quercetin in grape skins and winemaking byproducts obtained from the same cultivar. Samples were eluted using a C18 narrow-bore column under isocratic conditions in less than 20 min. Quantification of trans-resveratrol and quercetin in red wine was performed without any sample pretreatment, whereas the determination of these phenolic compounds in grape skins and wine pomage required a solvent extraction procedure. Linearity was demonstrated over the 0.39-12.5 and 0.45-57.6 microg/mL range for trans-resveratrol and quercetin, respectively. Detection limits in real samples were in the low ppm level (0.07 mg/L for trans-resveratrol and 0.12 mg/L for quercetin). The HPLC-UV/DAD method was applied for the routine analyses of red wine and grape skin and winemaking byproduct extracts to evaluate their trans-resveratrol and quercetin content. In particular, a very high content of quercetin was found in wine pomace, suggesting the use of this wine byproduct as a potential source of this health-promoting phenolic compound.

Quantification of Quercetin in Onion (Allium Cepa) after Domestic Processing

The flavonol quercetin has been reported as having many health benefits, including a reduction in the risk of developing cardiovascular disease, stroke, and some types of cancer. The overall content of quercetin in onion was examined in four yellow varieties (`Rio Rita', `RNX 10968', `Predator', and `Tamara') and one red variety purchased at a local grocery store. Each bulb was quartered, with one quarter saved as a control and the other three quarters subjected to three cooking treatments that simulated common domestic processing methods of preparing onion. The treatments included sautéing in sunflower oil for 5 minutes at 93 °C, baking for 15 min. at 176 °C, and boiling for 5 minutes in distilled water. Samples were frozen in liquid nitrogen, ground to a fine powder, blended with 80% EtOH, and filtered for quercetin extraction. The filtrate was then analyzed with a spectrophotometer (uv 374 nm). Quercetin concentrations were obtained in mg quercetin/kg fresh weight of tissue by regressing spectrophotometer readings onto a standard curve. Significant differences between varieties were found when examining fresh samples alone with the red variety containing the highest content of quercetin. Results of cooking showed that sautéing produced an overall 27% gain in quercetin concentration (significantly higher than the fresh control), baking produced an overall 4% gain in concentration (insignificant from the fresh control), while boiling produced an overall 18% loss in quercetin concentration (significantly lower than the fresh control).

Reconnaissance chimiosystématique et biométrique du pin de tourbière Pinus x uliginosa (Neumann)

The flavonic profile of Peatbog pines Pinus uliginosa Neumann from Poland and France (with low quercetin content) are close to that of Mugo pine P. mugo Turr. and Mountain pine P. uncinata Ram.; in this respect, the two latter species are indistinguishable. However, the presence of some individuals of sylvestris type (with high quercetin content) is notable; moreover, trees with intermediate quercetin contents can be numerous, revealing a hybridization process in good accordance with Hardy-Weinberg's rule. Foliar morphometry (fineness index: L/P) tends toward the uncinata/mugo type. If specific status is to be conferred to Peatbog pine, it should be admitted that it results from the persistance in this biotope of past crossbreeding between Mountain/Mugo pine and Scots pine (more precisely its chemomorph T-, taxifolin absent), with the second taxon subordinated to the first. A comparison is made with current hybridization and introgression processes at high altitudes, which lead to the Bouget pine Pinus bougeti Flous from the same parent species.

445 PB 256 QUERCETIN AND QUERCETIN GLYCOSIDE CONTENT VARIATION IN DIFFERENT ONION (Allium cepa L.) VARIETIES AND GENOTYPES

The anti carcinogenic flavonol, aglycone, or free quercetin and quercetin glycoside content of seventeen onion varieties and 22 genotypes (Asgrow seed co.) and also 37 breeding lines (Texas A&M University) were analyzed by high performance liquid chromatography (HPLC). Quercetin glycosides were hydrolyzed into aglycones. Total quercetin content in yellow and red onions varied from 80.34 to 286.4 mg/kg fresh weight in different varieties. Marked variation in total quercetin content between Texas A&M breeding lines (56-202 mg/kg fresh weight) and Asgrow breeding lines (54-287 mg/kg fresh weight) was observed. White onions contain trace amount of total quercetin. Free quercetin in Texas A&M breeding line 20272-G was 12.4 mg/kg fresh weight; however, other varieties and breeding lines contain negligible amount of free quercetin. It was concluded that the `designer' onion varieties with high quercetin content for health consciousness can be produced.