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ABSTRACT The aim of the study was to investigate the anti-rheumatoid arthritic activity of four flavonoids from Daphne genkwa (FFD) in vivo and in vitro. Flavonoids of D. genkwa were [...]

ABSTRACT The present study was designed to evaluate the antihyperglycemic potential of tangeretin on the activities of key enzymes of carbohydrate and glycogen metabolism in control and streptozotocin induced diabetic [...]

ABSTRACT We previously demonstrated that ethyl acetate extracts of Kaempferia parviflora Wall. Ex Baker (KPE) improve insulin resistance in TSOD mice and showed that its components induce differentiation and adipogenesis [...]

ABSTRACT The Cecropia genus is widely distributed in Latin America including at least 60 species, and some of them are commonly used in traditional medicine for the treatment of several [...]

ABSTRACT Isoliquiritigenin (ISL), a chalcone and liquiritigenin (LTG), a flavonoid found in licorice roots and several other plants. ISL displays antioxidant, anti-inflammatory, antitumor and hepatoprotective activities whereas LTG is an [...]

Flavonoids constitute a group of polyphenols widely distributed in plants and are assumed to have beneficial effects on human health when present in food. The phenolic content of apple fruit skin and leaves was determined at the developmental stage of each organ. Phenolic levels decreased on a dry weight basis during the seasonal development of fruits and leaves with respect to their ontogenesis but the single compounds did not behave uniformly. A shift in flavanol pools from monomeric to oligomeric structures during fruit growth indicated the biosynthetic tendency towards the formation of procyanidins at the end of the growing period. A gas chromatography-mass spectrometry (GC-MS) method was developed for the separation and determination of three major flavones: sinensetin (SEN), rutin (RU) and 3'-hydroxy-5, 6, 7, 4'-tetramethoxyflavone (TMF) and rosmarinic acid (RA), a caffeic acid derivative in the pink skin of apple fruit. The GC-MS method was applied for the quantification of SEN, RU, TMF and RA in apple fruit collected from different local markets of Bangladesh during the period of November 2008. Apple fruit skin contains several bioactive phytochemicals including polyphenols such as flavones and phenolic acids. Dehydrated apple skin powder was used to evaluate the recovery of selected flavones and rosmarinic acid using water, methanol, acetone, chloroform, aqueous 50% methanol, and aqueous 70% acetone at 40 °C. The retrieved extracts were subjected to qualitative and quantitative GC-MS analysis. Highest amount of sinensetin (SEN) and rutin (RU) was found in the chloroform extract, which was obtained for 4 to 6 hours of extraction at 40°C. Higher proportion of 3'-hydroxy-5, 6,7,4'-tetramethoxyflavone (TMF) was obtained in pure acetone and as well as 70% acetone where the extraction period 4 to 6 hours, respectively. Similar yield of rosmarinic acid (RA) was obtained in aqueous 70% acetone extracts when the periods of extraction were 2, 4, 6 and 8 hours, respectively. Key words: Quantification, Malus sylvestris, Lipophillic flavones, GC-MS, INTRODUCTION Phenolic acids and flavonoids are secondary metabolites found in most of the plants. These compounds protect plants against ultraviolet radiation, pathogens, and herbivores [1]. The daily intake of flavonoids [...]

The bifunctional proline catabolic flavoenzyme, proline utilization A (PutA), catalyzes the oxidation of proline to glutamate via the sequential activities of FAD-dependent proline dehydrogenase (PRODH) and [NAD.sup.+]-dependent [[DELTA].sup.1]-pyrroline-5-carboxylate dehydrogenase (P5CDH) domains. Although structures for some of the domains of PutA are known, a structure for the full-length protein has not previously been solved. Here we report the 2.1 [Angstrom] resolution crystal structure of PutA from Bradyrhizobium japonicum, along with data from small-angle x-ray scattering, analytical ultracentrifugation, and steady-state and rapid-reaction kinetics. PutA forms a ring-shaped tetramer in solution having a diameter of 150 [Angstrom]. Within each protomer, the PRODH and P5CDH active sites face each other at a distance of 41 [Angstrom] and are connected by a large, irregularly shaped cavity. Kinetics measurements show that glutamate production occurs without a lag phase, suggesting that the intermediate, [[DELTA].sup.1]-pyrroline-5-carboxylate, is preferably transferred to the P5CDH domain rather than released into the bulk medium. The structural and kinetic data imply that the cavity serves both as a microscopic vessel for the hydrolysis of [[DELTA].sup.1]-pyrroline-5-carboxylate to glutamate semialdehyde and a protected conduit for the transport of glutamate semialdehyde to the P5CDH active site. proline catabolism | substrate channeling www.pnas.org/cgi/doi/10.1073/pnas.0906101107

DNA microarray analysis revealed that transcription of the Bacillus subtilis yetM gene encoding a putative flavin adenine dinucleotide-dependent monooxygenase was triggered by certain flavonoids during culture and was derepressed by disruption of the yetL gene in the opposite orientation situated immediately upstream of yetM, which encodes a putative MarR family transcriptional regulator. In vitro analyses, including DNase I footprinting and gel retardation analysis, indicated that YetL binds specifically to corresponding single sites in the divergent yetL and yetM promoter regions, with higher affinity to the yetM region; the former region overlaps the Shine-Dalgarno sequence of yetL, and the latter region contains a perfect 18-bp palindromic sequence (TAGTTAGGCGCCTAACTA). In vitro gel retardation and in vivo lacZ fusion analyses indicated that some flavonoids (kaempferol, apigenin, and luteolin) effectively inhibit YetL binding to the yetM cis sequence, but quercetin, galangin, and chrysin do not inhibit this binding, implying that the 4-hydroxyl group on the B-ring of the flavone structure is indispensable for this inhibition and that the coexistence of the 3-hydroxyl groups on the B- and C-rings does not allow antagonism of YetL.

Objectives: To measure the relationship between quercetin and naringenin intakes as estimated by food frequency questionnaire (FFQ), and the urinary excretion of quercetin and naringenin aglycones after their enzymatic hydrolysis in human volunteers. Subjects and methods: Volunteers were recruited via the Human Nutrition Unit volunteer databank at the Institute of Food Research, Norwich. Sixty-three volunteers were recruited into the study, of which 14 were excluded and 49 completed the study. A modified FFQ was developed and used to estimate daily intake of quercetin and naringenin in 49 healthy volunteers who also provided five 24-h urine samples over a 2-week period. Urinary excretion of quercetin and naringenin metabolites was determined by solid-phase extraction and high-pressure liquid chromatography. Results: The estimated mean intakes of quercetin and naringenin were 29.4 mg (s.d. 15.0) and 58.1 mg (s.d. 62.7) per day, respectively. Mean urinary excretion of quercetin was 60.1 ug (s.d. 33.1) and that of naringenin was 0.56 mg (s.d. 0.4). The correlation between FFQ estimated intake of quercetin and naringenin and levels excreted in the urine were r=0.82 (P Conclusions: We observed a statistically significant correlation between the urinary excretion of quercetin and naringenin metabolites and their dietary intake as estimated by FFQ. Use of FFQs in epidemiological studies requiring an estimate of flavonoid intake seems justified. doi:10.1038/sj.ejcn.1602827; published online 30 May 2007 Keywords: cancer; flavonoids; quercetin; naringenin; portion size; FFQ, Introduction Flavonoids are water-soluble polyphenolic compounds found in many fruits and vegetables in the human diet. There is a considerable interest in the possibility that flavonoids function as natural anticarcinogens, [...]

Serum C-reactive protein (CRP) is a biomarker for chronic inflammation and a sensitive risk factor for cardiovascular diseases. Though CRP has been reported to be related to food intake, there is no documentation of a direct association with flavonoid intake. We aimed to test the associations between dietary flavonoid intake and serum CRP concentrations among U.S. adults after adjusting for dietary, sociodemographic, and lifestyle factors. Data from the NHANES 1999-2002 were used for this cross-sectional study. Subjects were [greater than or equal to] 19-y-old adults (n = 8335), and did not include pregnant and/or lactating women. Flavonoid intake of U.S. adults was estimated by the USDA flavonoid databases matched with a 24-h dietary recall in NHANES 1999-2002. The serum CRP concentration was higher in women, older adults, blacks, and smokers, and in those with high BMI or low exercise level, and in those taking NSAID, than in their counterparts (P< 0.01 ). Intakes of apples and vegetables were inversely associated with serum CRP concentrations after adjusting for covariates (P < 0.05). Total flavonoid and also individual flavonol, anthocyanidin, and isoflavone intakes were inversely associated with serum CR P concentration after adjusting for the covariates (P < 0.05). Among the flavonoid compounds investigated, quercetin, kaempferol, malvidin, peonidin, daidzein, and genistein had inverse associations with serum CRP concentration (P < 0.05). These associations did not change even after the additional adjustment for fruit and vegetable consumption. Our findings demonstrate that intake of dietary flavonoids is inversely associated with serum CRP concentrations in U.S. adults. Intake of flavonoid-rich foods may thus reduce inflammation-mediated chronic diseases.

Abstract A number of flavonoids isolated from Lonchocarpus spp. were evaluated for their antiprotozoal and cytotoxic activity. Flavone 6 and chalcone 7 were found to be the most active against [...]

The catabolic pathway for flavodoxin has yet to be clarified for any bacterial species. In this study, we found that the flavin mononucleotide in the flavodoxin of Helicobacter pylori is degraded to riboflavin via the phosphomonoesterase activity of class C acid phosphatase. The result is a conversion of holoflavodoxin to apoflavodoxin.

Bacillus subtilis LmrA is known to be a repressor that regulates the lmrAB and yxaGH operons; lmrB and yxaG encode a multidrug resistance pump and quercetin 2,3-dioxygenase, respectively. DNase I footprinting analysis revealed that LmrA and YxaF, which are paralogous to each other, bind specifically to almost the same cis sequences, LmrA/YxaF boxes, located in the promoter regions of the ImrAB operon, the yxaF gene, and the yxaGH operon for their repression and containing a consensus sequence of AWTATAtagaNYGgTCTA, where W, Y, and N stand for A or T, C or T, and any base, respectively (three-out-of-four match [in lowercase type]). Gel retardation analysis indicated that out of the eight flavonoids tested, quercetin, fisetin, and catechin are most inhibitory for LmrA to DNA binding, whereas quercetin, fisetin, tamarixetin, and galangin are most inhibitory for YxaF. Also, YxaF bound most tightly to the tandem LmrA/YxaF boxes in the yxaGH promoter region. The lacZ fusion experiments essentially supported the above-mentioned in vitro results, except that galangin did not activate the lmrAB and yxaGH promoters, probably due to its poor incorporation into cells. Thus, the LmrA/YxaF regulon presumably comprising the ImrAB operon, the yxaF gene, and the yxaGH operon is induced in response to certain flavonoids. The in vivo experiments to examine the regulation of the synthesis of the reporter [beta]-galactosidase and quercetin 2,3-dioxgenase as well as that of multidrug resistance suggested that LmrA represses the lmrAB and yxaGH operons but that YxaF represses yxaGH more preferentially.

Several strategies to reengineer central metabolism in Escherichia coli were investigated for synthesis of flavanones. The reengineering was targeted towards the multisubunit complex of acetyl-CoA carboxylase (ACC)-biotin ligase (BirA) and enzymes in acetate assimilation pathways in Escherichia coli.

The dietary flavonoid quercetin reduces blood pressure and improves endothelial function in several rat models of hypertension. We analyzed the effects of quercetin and its methylated metabolite isorhamnetin on the aortic endothelial dysfunction induced by incubation with angiotensin II (Angll) in vitro for 6 h. Angll diminished the relaxant responses to acetylcholine in phenylephrine-contracted aorta. Coincubation with quercetin or isorhamnetin, or addition of superoxide ([0.sub.2]-) dismutase or apocynin to the assay medium, prevented these inhibitory effects. At 6 h, Angll induced a marked increase in [0.sub.2]- production as measured by dihydroethidium fluorescence, which was prevented by quercetin and isorhamnetin. Angll also increased the expression of p[47.sup.phox], a regulatory subunit of the membrane NADPH oxidase. Immunohistochemical analysis revealed that overexpression of p[47.sup.phox] occurred mainly in the medial layer, p[47.sup.phox] overexpression was also prevented by quercetin and isorhamnetin. Taken together, these results show for the first time, to our knowledge, that quercetin and isorhamnetin prevent Angll-induced endothelial dysfunction by inhibiting the overexpression of p[47.sup.phox] and the subsequent increased [0.sub.2]- production, resulting in increased nitric oxide bioavailability. J. Nutr. 137: 910-915, 2007.

This article provides an overview of current research on flavonoids as presented during a workshop entitled, 'Flavonoids and Heart Health,' held by the ILSI North America Project Committee on Flavonoids in Washington, DC, May 31 and June 1, 2005. Because a thorough knowledge and understanding about the science of flavonoids and their effects on health will aid in establishing dietary recommendations for bioactive components such as flavonoids, a systematic review of the science of select flavonoid classes (i.e., flavonols, flavones, flavanones, isoflavones, flavan-3-ols, anthocyanins, and proanthocyanidins) was presented. The objectives of the workshop were to 1) present and discuss current research on flavonoid intake and the relation between flavonoids and heart health; 2) develop information that could lead to expert consensus on the state-of-the-science of dietary intake of flavonoids on heart health; and 3) summarize and prioritize the research needed to establish the relations between specific flavonoids and heart health. Presentations included the basics of the biology of flavonoids, including the types and distribution in foods, analytical methodologies used to determine the amounts in foods, the bioavailability, the consumption patterns and potential biomarkers of intake, risk assessment and safety evaluation, structure/ function claims, and the proposed mechanism(s) of the relation between certain flavonoids and heart health endpoints. Data presented support the concept that certain flavonoids in the diet can be associated with significant health benefits, including heart health. Research gaps were identified to help advance the science.