Effect Of Quercetin Supplementation Research Articles

The effect of quercetin supplementation on clinical outcomes in COVID-19 patients: A systematic review and meta-analysis.

Coronavirus disease (COVID-19) affects both the respiratory system and the body as a whole. Natural molecules, such as flavonoid quercetin, as potential treatment methods to help patients combat COVID-19. The aim of this systematic review and meta-analysis is to give a comprehensive overview of the impact of quercetin supplementation on inflammatory factors, hospital admission, and mortality of patients with COVID-19. The search has been conducted on PubMed, Scopus, Web of Science, EMBASE, and the Cochrane Library using relevant keywords until August 25, 2023. We included randomized controlled trials (RCTs) comparing COVID-19 patients who received quercetin supplementation versus controls. We included five studies summarizing the evidence in 544 patients. Meta-analysis showed that quercetin administration significantly reduced LDH activity (standard mean difference (SMD): -0.42, 95% CI: -0.82, -0.02, I 2 = 48.86%), decreased the risk of hospital admission by 70% (RR: 0.30, 95% CI: 0.14, 0.62, I 2 = 00.00%), ICU admission by 73% (RR: 0.27, 95% CI: 0.09, 0.78, I 2 = 20.66%), and mortality by 82% (RR: 0.18, 95% CI: 0.03, 0.98, I 2 = 00.00%). No significant changes in CRP, D-dimmer, and ferritin were found between groups. Quercetin was found to significantly reduce LDH levels and decrease the risk of hospital and ICU admission and mortality in patients with COVID-19 infection.

Effect of quercetin supplementation on growth performance, nutrient digestibility, excreta bacterial count, noxious gas emission, and meat quality of broilers when fed different protein diets

This study aimed to evaluate the effect of flavonoid supplementation to a low-protein diet (LCP) on growth performance, nutrient digestibility, excreta bacterial count, and excreta gas emission of broilers. In total, 800 one-day-old Ross 308 broilers (BW; 42.90 ± 1.43 g) were randomly sorted into one of the 4 dietary treatments (10 pens/treatment; 20 birds/pen). Treatment diets were high-protein diet (HCP), basal diet; LCP, basal diet − 2.5% protein; TRT1, LCP + 0.025% quercetin; and TRT2, LCP + 0.050% quercetin. Experimental diets were provided to broilers from days 8 to 35. HCP, TRT1, and TRT2 showed higher body weight gain (BWG) than the LCP group during days 8–21 and in the overall experiment. However, feed conversion ratio of the HCP group was improved than that of the LCP group during days 8–21 and in the overall period. The increasing level of quercetin supplementations brought a linear increase in BWG. Lactobacillus, Escherichia coli, and Salmonella counts in excreta samples of the experimental groups showed no significant difference. Flavonoid supplementation (0.050%) reduced drip loss in breast muscle more than that in the LCP group and showed a linear reduction. Through improved digestion, quercetin addition to an LCP reversed the BWG.

Effect of Quercetin Supplementation in Extender on Sperm Kinematics, Extracellular Enzymes Release, and Oxidative Stress of Egyptian Buffalo Bulls Frozen-Thawed Semen.

Buffalo spermatozoa are more sensitive for cryopreservation compared to other species. This study aimed to evaluate the consequences of quercetin against cryodamage of buffalo frozen–thawed spermatozoa characteristics. Semen of Egyptian bulls (n = 4) was extended in OptiXcell extender incorporated with quercetin at 0 (control), 2.5, 5.0, 10.0, 20.0, 40.0, and 80.0 μM before cryopreservation. Frozen–thawed semen was evaluated for sperm motility by computer-assisted sperm analyzer (CASA), viability, morphology, membrane, and acrosome integrities. The kinematics parameters including average path velocity (VAP; μm/s), straight linear velocity (VSL; μm/s), curvilinear velocity (VCL; μm/s), amplitude of lateral head displacement (ALH; μm), beat cross frequency (BCF; Hz), linearity [LIN, (VSL/VCL) × 100], and straightness [STR, (VSL/VAP) × 100] were assessed. The sperm-free extender was evaluated for aspartate aminotransferase (AST), alanine aminotransferase (ALT), and H2O2. Homogenized sperm cells were evaluated for oxidative stress biomarkers [superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX)], and lipid peroxidation [malondialdehyde (MDA)]. The highest values of total motility, progressive motility, viability, intact acrosome, and membrane integrity substantially improved with 10 μM of quercetin. STR (%) was substantially low (P < 0.01), and VCL (μm/s) and ALH (μm) were markedly high (P < 0.05) in 10 μM of quercetin. The outflow of ALT enzyme to extracellular fluid was lower with 10 μM of quercetin (P < 0.001) and higher at 2.5 μM of quercetin. The spermatozoa leaked AST was markedly lower at 5.0, 10 (P < 0.001) and 20 μM (P < 0.05) of quercetin. The activity of antioxidant enzymes was eminently low at all quercetin concentrations, and this was accompanied by the decrease in H2O2 in the media. SOD activity at 10–80 μM, CAT at 5.0–40 μM, and GPX at 2.5–80.0 μM of quercetin in spermatozoa were substantially low. MDA level significantly (P < 0.001) decreased at all quercetin concentrations. In conclusion, the incorporation of quercetin at the level of 10 μM is promising in improving buffalo semen characteristics and lower the freezing–thawing oxidative stress.

Effect of quercetin supplementation on the growth, feed efficiency and serum hormone levels of New Zealand White rabbits

Meat rabbits could provide a new avenue for agricultural development in South Africa, and flavonoids may be able to improve their live performance. This study investigated the effects of quercetin dihydrate (0 and 2 g/kg feed) on the growth parameters and serum-free triiodothyronine (fT3), free thyroxine, somatotropin, and cortisol levels of growing rabbits. It also provides the first growth and feed conversion ratio (FCR) data for South African New Zealand Whites. Control (Ctrl) and quercetin-supplemented (Qrc) diets were provided to 34 (16 male, 18 female) and 32 (15 male, 17 female) rabbits, respectively, from 5 to 12 weeks old. Live performance was measured weekly, and serum hormone levels were determined at 11 weeks old. Overall, the rabbits performed well for live weight and growth rate, growing from 1052 ± 13.4 g to 3192 ± 45.3 g (5-12 weeks). Females had higher cortisol levels than males, as found for other species (female = 10.9 ng/mL, male = 3.89 ng/mL). Qrc rabbits tended to have a higher overall FCR than Ctrl rabbits (Ctrl = 3.83, Qrc = 4.01), possibly due to lower feed digestibility, and had smaller sex differences in growth and FCR than Ctrl rabbits, possibly owing to xenoestrogenic activity. They also tended to have higher fT3 levels than Ctrl rabbits (Ctrl = 3.62 ng/mL, Qrc = 4.98 ng/mL), possibly owing to the inhibition of binding to transthyretin. However, it does not seem that the provision of quercetin is commercially justified for improving the live performance of rabbits.

60 Quercetin protects bovine pre-implantation embryos against oxidative stress via activation of Nrf2 signaling pathway

High atmospheric oxygen level during in vitro embryo culture system is reported to induce oxidative stress, leading to an increased intracellular reactive oxygen species (ROS) accumulation and lower the quality and development of the embryos. The Nrf2 is a redox sensitive transcription factor, which regulates the antioxidant machinery against oxidative stress in bovine pre-implantation embryos (Amin et al. 2014Mol. Reprod. Dev. 81, 497-513). Quercetin is a plant-derived flavonoid found in fruits and vegetables with antioxidant, anti-inflammatory, and anti-apoptotic properties. The effect of these antioxidants on the development and quality of bovine pre-implantation embryos with respect to the activation of the Nrf2 signalling pathways is not yet discovered. Here, we aimed to investigate the effect of quercetin supplementation on the activation of the Nrf2 signalling pathway and the subsequent impact on the quality of bovine embryos. For this, presumptive bovine zygotes were cultured in SOFaa embryo culture media supplemented with or without 10 µM quercetin (482 and 485 zygotes, respectively) and incubated under high oxygen level (20%) conditions. Day 7 and Day 8 blastocysts were analysed for the accumulation intracellular ROS and mitochondrial activity using H2DCFDA and MitoTracker® Red, respectively. Thereafter, blastocysts from both groups were subjected to total RNA isolation using Norgen total RNA purification plus kit (BioTek, Winooski, VT, USA). The relative abundance of Nrf2 and its downstream antioxidant genes (NQO1, PRDX1, SOD1, and CAT) was quantified using quantitative PCR. Moreover, the protein level of Nrf2 was detected using immunofluorescence staining. Data from 4 independent biological replicates were statistically analysed using a 2-tailed Student’s t-test. A significant difference in the mean value among treatments was determined at P=0.05. Results showed that quercetin supplementation in embryo culture medium significantly increased the blastocyst total cell number both at Day 7 (125±7.98 v. 100±3.74; P=0.007) and Day 8 (128±4.49 v. 95±3.15; P&amp;lt;0.0001). However, no difference was observed in the quercetin-treated group compared with control with respect to the cleavage rate (85.89±1.11v. 83.86±1.27; P=0.2) as well as the blastocyst rate at Day 7 (24.57±4.94 v. 27.23±1.68; P=0.64) and Day 8 (41.17±3.70 v. 38.87±0.85; P=0.58). Interestingly, quercetin-supplemented blastocysts showed a significant reduction in intracellular ROS level and increment in the mitochondrial activity compared with untreated counterparts. Supplementation of quercetin activated the Nrf2 transcriptional factor both at the mRNA and protein level, which subsequently activated the transcription of the aforementioned downstream antioxidant genes. In conclusion, supplementation of quercetin to embryo culture media protects embryos against oxidative stress by activating the Nrf2-mediated oxidative stress response mechanism, which leads to reduced accumulation of ROS and elevated mitochondrial activity.

Quercetin improves developmental competence of mouse oocytes by reducing oxidative stress during in vitro maturation

Abstract Quercetin is a natural flavonoid with strong antioxidant activity. In the present study, we evaluate the influence of different concentrations of quercetin (QT) on intracytoplasmic oxidative stress and glutathione (GSH) concentration, during in vitro maturation (IVM) and fertilization in mouse oocytes. IVM was carried out in the presence of control (QT0), 5 (QT5), 10 (QT10), and 20 (QT20) μg/mL of QT. Nuclear maturation, intracellular GSH and ROS content were evaluated following the IVM. In these oocytes, we subsequently evaluated the effect of QT supplementation on embryo development, including 2-cell, 8-cell, and blastocyst rate. The results of the present study showed that the supplementation of 10 μg/mL QT in maturation medium increased the number of MII oocytes. In addition, fertilization and blastocyst rate in QT10 treatment group were significantly higher in comparison to the other groups, and elevated the amount of intracellular GSH content compared to other QT concentrations and control groups. The intracellular ROS level was the lowest among oocytes matured in Q5 and Q10 treatment groups. This result suggested that quercetin dose-dependently improves nuclear maturation and embryo development, via reducing intracytoplasmic oxidative stress in mature oocyte.

Pre-clinical studies on beneficial effect of quercetin supplementation in improving mitochondrial dysfunctions induced by 3-nitropropionic acid: Implications in Huntington's disease

Pre-clinical studies on beneficial effect of quercetin supplementation in improving mitochondrial dysfunctions induced by 3-nitropropionic acid: Implications in Huntington's disease

Effects of Quercetin Supplementation on Endurance Performance and Maximal Oxygen Consumption: A Meta-Analysis

Lately, the effect of quercetin supplementation (QS) on endurance performance (EP) and maximal oxygen consumption (VO2max) has been receiving much scientific and media attention. Therefore, a meta-analysis was performed to determine QS's ergogenic value on these variables. Studies were located with database searches (PubMed and SPORTDiscus) and cross-referencing. Outcomes represent mean percentage changes in EP (measured via power output) and VO2max between QS and placebo. Random-effects model meta-regression, mixed-effects model analog to the ANOVA, random-effects weighted mean effect summary, and magnitude-based inferences analyses were used to delineate the effects of QS. Seven research articles (representing 288 subjects) were included, producing 4 VO2max and 10 EP effect estimates. Mean QS daily intake and duration were, respectively, 960 ± 127 mg and 26 ± 24 d for the EP outcome and 1,000 ± 0 mg and 8 ± 23 d for the VO2max outcome. EP was assessed during exercise with a mean duration of 79 ± 82 min. Overall, QS improved EP by 0.74% (95% CI: 0.10-1.39, p = .02) compared with placebo. However, only in untrained individuals (0.83% ± 0.78%, p = .02) did QS significantly improve EP (trained individuals: 0.09% ± 2.15%, p = .92). There was no relationship between QS duration and EP (p = .69). Overall, QS increased VO2max by 1.94% (95% CI: 0.30-3.59, p = .02). Magnitude-based inferences suggest that the effect of QS on EP and VO2max is likely to be trivial for both trained and untrained individuals. In conclusion, this meta-analysis indicates that QS is unlikely to prove ergogenic for aerobic-oriented exercises in trained and untrained individuals.

Effect of Quercetin Supplementation on Repeated-Sprint Performance, Xanthine Oxidase Activity, and Inflammation

Maintenance of repeated-sprint performance is a goal during team-sport competition such as soccer. Quercetin has been shown to be an adenosine-receptor antagonist and may reduce oxidative stress via inhibition of the enzyme xanthine oxidase (XO). The purpose of the study was to determine the effect of quercetin consumption on performance of repeated sprints and, secondarily, the XO and inflammatory-marker response induced by repeated-sprint exercise. Fifteen recreationally active, young adult men completed 2 repeated-sprint tests (RST), 12 × 30-m maximal-effort sprints (S1-S12), each after 1 wk supplementation with a placebo, a 6% carbohydrate commercial sports drink, or that drink with 500 mg of quercetin-3-glucoside, consumed twice a day (1,000 mg/d). Blood samples were collected before supplementation (B0), at baseline before each RST (B1), immediately after RST (B2), and 1 hr after RST (B3). Mean sprint time increased progressively and was significantly higher by S9 for both treatments (5.9%); however, there were no significant differences between treatments. Percent fatigue decrement (%FD) for placebo (3.8% ± 2.3%) was significantly less than with quercetin (5.1% ± 2.7%). Changes in blood XO, IL-6, and uric acid from B1 to B2 were +47%, +77%, and +25%, respectively, with no difference by treatment. In conclusion, repeated-sprint performance was not improved by quercetin supplementation and was worse than with placebo when expressed as %FD. Quercetin did not attenuate indicators of XO activity or IL-6, a marker of the inflammatory response after sprint exercise.

No evidence for a thermic effect of the dietary flavonol quercetin: a pilot study in healthy normal-weight women

Our objective was to investigate the effect of quercetin supplementation on fasting resting energy expenditure (REE) and respiratory quotient (RQ) in humans. Six healthy, normal-weight women (mean age 25.5±1.6years, body mass index 21.4±1.5kg/m(2)) participated in a randomized, placebo-controlled, double-blinded crossover study. Treatments were administered as capsules of 150mg quercetin (aglycone) or placebo. The acute response was measured by indirect calorimetry for 3h following ingestion. Blood pressure and pulse rate were assessed in 30-min intervals. On the following day, 24h after capsule intake, a follow-up measurement was performed. Baseline (t (0)) REE adjusted for fat-free mass was 4.7±0.26kJ/min (quercetin) and 4.8±0.35kJ/min (placebo) and did not significantly change between baseline and end (t (180)) in either group (P=0.992 for time effect in repeated measures analysis of variance; P=0.581 for time×treatment interaction). Mean RQ was 0.78±0.04 (quercetin) and 0.77±0.04 (placebo). RQ values decreased slowly and to a similar extent during both treatments (P<0.001 for time; quercetin, -0.09±0.05; placebo, -0.08±0.03; P=0.877 for time×treatment interaction). Resting systolic and diastolic blood pressure, pulse pressure as well as resting pulse rate did not significantly change between baseline and end in either treatment group. No significant differences were found between the results of the baseline measurement and 24h after treatment. In conclusion, the present pilot study provides no evidence for a thermic effect of quercetin in humans.

Effect of quercetin supplementation on maximal oxygen uptake in men and women

Quercetin is a naturally occurring flavonoid with anti-oxidant and anti-inflammatory properties. The effect of quercetin supplementation on maximal oxygen uptake ([Vdot]O2max) is unknown. The purpose of this investigation was to test the effects of quercetin supplementation on [Vdot]O2max in untrained, sedentary individuals. After baseline treadmill [Vdot]O2max testing, 11 participants (5 males, 6 females) ingested either placebo or quercetin-supplemented (1000 mg · day−1) food bars in a randomized, double-blind, counterbalanced, crossover research design. The participants ingested food bars for six consecutive mornings (5 days). On the sixth morning, participants underwent repeat [Vdot]O2max testing. After a 22 day wash-out, the participants repeated baseline [Vdot]O2max testing, daily consumption of the opposite food bars, and post-supplementation [Vdot]O2max testing. The condition × time interaction for [Vdot]O2max was non-significant when expressed in absolute (litres · min−1; P = 0.929) and relative (ml · kg−1 · min−1; P = 0.778) terms. These findings were similar when taking sex into account (P > 0.05). The mean difference in [Vdot]O2max change from pre to post between groups (quercetin vs. placebo) was 0.139 ml · kg−1 · min−1 (P = 0.780). Other physiological measures also were similar between conditions (P > 0.05). In conclusion, 5 days of quercetin supplementation did not influence [Vdot]O2max or related variables in sedentary men and women.