High Content Of Flavonols Research Articles

Antiglycation and Antioxidant Properties of Momordica charantia.

The accumulation of advanced glycation endproducts (AGEs) and oxidative stress underlie the pathogenesis of diabetic complications. In many developing countries, diabetes treatment is unaffordable, and plants such as bitter gourd (or bitter melon; Momordica charantia) are used as traditional remedies because they exhibit hypoglycaemic properties. This study compared the antiglycation and antioxidant properties of aqueous extracts of M. charantia pulp (MCP), flesh (MCF) and charantin in vitro. Lysozyme was mixed with methylglyoxal and 0–15 mg/ml of M. charantia extracts in a pH 7.4 buffer and incubated at 37°C for 3 days. Crosslinked AGEs were assessed using gel electrophoresis, and the carboxymethyllysine (CML) content was analyzed by enzyme-linked immunosorbent assays. The antioxidant activities of the extracts were evaluated using assays to assess DPPH (1,1-diphenyl-2-picryl-hydrazyl) and hydroxyl radical scavenging activities, metal-chelating activity and reducing power of the extracts. The phenolic, flavonol and flavonoid content of the extracts were also determined. All extracts inhibited the formation of crosslinked AGEs and CML in a dose-dependent manner, with MCF being the most potent. The antioxidant activity of MCF was higher than that of MCP, but MCP showed the highest metal-chelating activity. MCF had the highest phenolic and flavonoid contents, whereas MCP had the highest flavonol content. M. charantia has hypoglycaemic effects, but this study shows that M. charantia extracts are also capable of preventing AGE formation in vitro. This activity may be due to the antioxidant properties, particularly the total phenolic content of the extracts. Thus, the use of M. charantia deserves more attention, as it may not only reduce hyperglycaemia but also protect against the build-up of tissue AGEs and reduce oxidative stress in patients with diabetes.

Flavonols Mediate Root Phototropism and Growth through Regulation of Proliferation-to-Differentiation Transition.

Roots normally grow in darkness, but they may be exposed to light. After perceiving light, roots bend to escape from light (root light avoidance) and reduce their growth. How root light avoidance responses are regulated is not well understood. Here, we show that illumination induces the accumulation of flavonols in Arabidopsis thaliana roots. During root illumination, flavonols rapidly accumulate at the side closer to light in the transition zone. This accumulation promotes asymmetrical cell elongation and causes differential growth between the two sides, leading to root bending. Furthermore, roots illuminated for a long period of time accumulate high levels of flavonols. This high flavonol content decreases both auxin signaling and PLETHORA gradient as well as superoxide radical content, resulting in reduction of cell proliferation. In addition, cytokinin and hydrogen peroxide, which promote root differentiation, induce flavonol accumulation in the root transition zone. As an outcome of prolonged light exposure and flavonol accumulation, root growth is reduced and a different root developmental zonation is established. Finally, we observed that these differentiation-related pathways are required for root light avoidance. We propose that flavonols function as positional signals, integrating hormonal and reactive oxygen species pathways to regulate root growth direction and rate in response to light.

Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States.

Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production.

Phytochemical Composition and Antibacterial Activity of Hydroalcoholic Extracts of Pterospartum tridentatum and Mentha pulegium against Staphylococcus aureus Isolates.

Pterospartum tridentatum and Mentha pulegium are largely used in Portuguese folk medicine to treat several human disorders and inflammatory processes but without any consistent evidence for those beneficial pointed properties. Thus, the aim of the current work is to evaluate its benefits and phytochemicals related to those beneficial properties. A distinct polyphenol profile between P. tridentatum and M. pulegium was found. Taxifolin, myricetin, ginestin, ginestein, and ginestein derivatives, biochanin A-glucoside, and biochanin A were identified in P. tridentatum, whilst in M. pulegium the luteolin-7-rutinoside, diosmin, and apigenin and respective derivatives were most representative polyphenols. These variations had implications in the antiradical and antibacterial activity and the P. tridentatum exhibited the highest antibacterial activity against methicillin-resistant and methicillin-sensitive Staphylococcus aureus MSSA, which was mainly dose-dependent. This antibacterial activity seems to be related to high content of flavonols, flavones, and isoflavones, which can act synergistically with each other against this type of bacteria. Our results showed consistent evidence that Pterospartum tridentatum and Mentha pulegium are an important reservoir of phytochemicals with antiradical activity and antibacterial capacity and thus they might be used in a preventive way or in a combined pharmaceutical and antibiotic therapy against pathogenic bacteria.

Quercetin Glycosides-rich Tea Cultivars (<i>Camellia sinensis</i> L.) in Japan

In an effort to identify tea cultivars with high flavonol content, we measured flavonol glycoside levels in the tea infusions of cultivars in the collection of the National Institute of Vegetable and Tea Science. The cultivars ‘Saemidori’, ‘Sofu’, ‘Surugawase’, ‘Fukumidori’, and ‘Asatsuyu’ among others could be effective sources of quercetin compared to other tea cultivars. Quercetin glycosides in “Saemidori” and “Sofu” remained at a relatively high level (110 – 170 µg/mL aglycone equivalent). These cultivars are indicated as effective sources of dietary quercetin, and are potential sources of quercetin-rich drinks.

Fruit Set of Apple Cultivars with Variouse Content of Flavonols in the Pollen and Phlorizin in the Styles of Flower Pestils

The process of fruit set of 10 apple varieties (Malusdomestica) having a different percentage of flavonols and water-soluble substances (WSS) in the pollen was studied. It was determined that the cultivars having higher content of flavonols and WSS in the pollen have a greater tendency to self-pollination; they are also better pollinators while cross-pollination. The percentage of phlorizin level in the styles of flower pistils of the same apple varieties was detected. It was also identified that varieties containing higher level of phlorizin in pistils have less pronounced tendency to selfpollination; their fruit set is weak while cross pollination. The conclusions about the possibility of using the flavonols percentage level in the pollen and phlorizin one in the styles of pistils as parameters for evaluation of the propensity to self-pollination and cross-fertility of apple varieties were done.

<em>In vitro</em> Inhibition of Acetyl Cholinesterase, Lipoxygenase, Xanthine Oxidase and Antibacterial Activities of Five <em>Indigofera</em> (Fabaceae) Aqueous Acetone Extracts from Burkina Faso

The aim of this study is to evaluate the inhibition of oxidative stress related enzymes of aqueous acetone extracts, as well as antibacterial activity from five <em>Indigofera</em> species well-known medicinal plant from Burkina. Also are investigated in this study the potential contribution of tannins and of flavonol in these activities Particularly, aqueous acetone extracts were investigated for their Lipoxygenase (LOX), Xanthine Oxidase (XO) and Acetylcholinesterase (AChE) inhibitions that are implied in inflammation, gout and Alzheimer’s etiology diseases. Interestingly, <em>I. macrocalyx</em> which had the highest flavonol content (of all) showed more inhibition against LOX and XO (51.16 and 77.33% respectively). Our study showed a significant correlation between XO inhibition and total flavonol content (R² = 0.9052). AChE was low sensible to all extracts. In contrast, the extracts were rich in tannin compounds especially in <em>I. tinctoria</em> extract. And results of the in vitro antibacterial activities of these extracts against five bacteria showed that all bacteria were sensible to all extracts particularly <em>S. typhimurium</em> and <em>B. cereus</em>. Our results suggest that the five studied species prove to be good sources of inhibition of the three enzymes involved in oxidative stress and also to have some antibacterial properties. That is what probably explains their uses in folk medicine, singularly, in the treatment of gout, dysentery and anti-inflammatory diseases.

Ultra Performance Liquid Chromatography–Tandem Quadrupole Mass Spectrometry Profiling of Anthocyanins and Flavonols in Cowpea (Vigna unguiculata) of Varying Genotypes

The structure of flavonoids in food plants affects bioactivity and important nutritional attributes, like micronutrient bioavailability. This study investigated flavonol and anthocyanin compositions of cowpea (Vigna unguiculata) of varying genotypes. Black, red, green, white, light brown, and golden brown cowpea phenotypes were analyzed for anthocyanins and flavonols using ultra performance liquid chromatography-tandem quadrupole mass spectrometry. Eight anthocyanins and 23 flavonols (15 newly identified in cowpea) were characterized. Mono-, di-, and tri(acyl)glycosides of quercetin were predominant in most phenotypes; myricetin and kaempferol glycosides were present only in specific phenotypes. The red phenotypes had the highest flavonol content (880-1060 μg/g), whereas green and white phenotypes had the lowest (270-350 μg/g). Only black (1676-2094 μg/g) and green (875 μg/g) phenotypes had anthocyanins, predominantly delphinidin and cyanidin 3-O-glucosides. Cowpea phenotype influenced the type and amount of flavonoids accumulated in the seed; this may have implications in selecting varieties for nutrition and health applications.

Concordance between antioxidant activities and flavonol contents in different extracts and fractions of Cuscuta chinensis

Chinese herbs employed in traditional Chinese medicine (TCM) have been used for centuries in the practice of medicated diet and dietetic therapy. The seed of Cuscuta chinensis Lam. (Convolvulaceae), a commonly used traditional Chinese herb, is frequently added in Chinese cooking and preparation of refreshments, including porridge and alcoholic beverages, to nourish the human body. In the present study, we compared the antioxidant activities of water and ethanol extracts from the seeds C. chinensis and also of its different organic fractions, including n-hexane, ethyl acetate, n-butanol and organic water, by assessing their DPPH (1,1-diphenyl-2-picryl hydrazine) free radical-scavenging, superoxide anion scavenging, anti-superoxide anion formation and anti-lipid peroxidation abilities. The flavonol contents of all test samples were analyzed by high-performance liquid chromatography with an ultraviolet (HPLC–UV) detector. The results showed that there is a direct correlation of the flavonol content with the antioxidant activities from the extracts and fractions of C. chinensis. Moreover, the ethyl acetate fraction demonstrated significantly better and higher antioxidant effects, and also had a higher flavonol content than had the remaining samples (P<0.05). The water fractions, however, exhibited the weakest antioxidant activity, and had low concentrations of flavonols. Thus, we suggest that the ethanol extract of C. chinensis, but not its water extract, could be used as a dietary nutritional supplement to promote human health and prevent oxidation-related diseases, due to its antioxidant properties.

Amount of characteristic compounds in 15 cultivars of onion (Allium cepa L.) in controlled field trials

AbstractBACKGROUND: In order to develop the production of sweet onions (Allium cepa L.) and onions with a high content of flavonols and fibre in Norway, it was necessary to evaluate available cultivars with respect to their content of selected chemical compounds. A field trial with 15 different cultivars was conducted at Landvik in southern Norway. Compounds that reflect onion pungency and sweetness (pyruvate, sugars) and parameters known to have a beneficial impact on health (fructo‐oligosaccharides (FOS), flavonols, antioxidant capacity) were analysed.RESULTS: The sweetest onions with respect to low content of pyruvate and high amount of fructose and glucose ranged in pyruvate content from 2.7 to 3.6 µmol mL−1. These cultivars were juicy and contained low amounts of FOS and total flavonols. The most pungent onions contained the highest amounts of FOS among the cultivars: 4.53, 3.80 and 5.81 g per 100 g fresh weight (FW) respectively. They also had a high content of flavonols (86.6, 159.2 and 97.6 mg per 100 g FW) and high dry weight content (14.6, 13.5 and 15.6 g per 100 g).CONCLUSION: The sweetest onion cultivars were found to be ‘NUN 9746’, ‘Musica’, ‘Domenica Supersweet’, ‘Colossus’ and ‘Cronus’. The most pungent cultivars were ‘Powell Brown’ and ‘Tilbury’, which also contained the highest amounts of flavonols and gave the highest Trolox equivalent antioxidant capacity (TEAC) values among the 15 cultivars. Copyright © 2007 Society of Chemical Industry

Flavonol Glycosides from Distilled Petals of Rosa damascena Mill

Flavonol glycosides were extracted from petals of Rosa damascena Mill. after industrial distillation for essential oil recovery and characterized by high-performance liquid chromatography-electrospray ionization mass spectrometry. Among the 22 major compounds analyzed, only kaempferol and quercetin glycosides were detected. To the best of our knowledge, the presence of quercetin 3-O-galactoside and quercetin 3-O-xyloside has so far not been reported within the genus Rosa. In addition, based on their fragmentation patterns, several acylated quercetin and kaempferol glycosides, some of them being disaccharides, were identified for the first time. The kaempferol glycosides, along with the kaempferol aglycone, accounted for 80% of the total compounds that were quantified, with kaempferol 3-O-glucoside being the predominant component. The high flavonol content of approximately 16 g/kg on a dry weight basis revealed that distilled rose petals represent a promising source of phenolic compounds which might be used as functional food ingredients, as natural antioxidants or as color enhancers.

Nutritional composition and flavonoid content of edible wild greens and green pies: a potential rich source of antioxidant nutrients in the Mediterranean diet

The traditional Greek diet is dominated by the high consumption of olive oil, fruit and vegetables. Antioxidants represent a common element in these foods and may be important mediators of the beneficial effect of this diet. Wild edible greens are frequently consumed throughout Greece. Seven edible wild greens and traditional Cretan green pies were analyzed for their nutritional composition and flavonoid content, in particular flavonols and flavones. A high nutritional value and a low energy value characterize the wild greens. These wild greens have a very high flavonol content when compared with regular fresh vegetables, fruits and beverages commonly consumed in Europe. Rumex obtusifolius was found to contain twice the amount of quercetin contained in onions. Two pieces of Cretan green pie (100 g) contain approximately 12 times more quercetin than one glass of red wine (100 ml) and three times more quercetin than a cup of black tea (200 ml). Wild greens potentially are a very rich source of antioxidant flavonols and flavones in the Greek diet.