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Quercetin for COVID-19
11 studies from 109 scientists
1,436 patients in 7 countries
Statistically significant lower risk for ICU, hospitalization, recovery, cases, and viral clearance.
43% lower risk in 10 RCTs CI 16-62%
Studies typically use advanced formulations for greatly improved bioavailability.
COVID-19 Quercetin studies. Sep 2023.
0 0.5 1 1.5+ All studies 49% With exclusions 41% Mortality 61% Hospitalization 48% Recovery 34% Cases 93% Viral clearance 56% RCTs 43% RCT mortality 61% Prophylaxis 93% Early 32% Late 34% Favorsquercetin Favorscontrol
Studies typically use advanced formulations for greatly improved bioavailability. Recent:
Quercetin has been officially adopted in part of 1 country. Submit updates/corrections.
Sep 28
Covid Analysis Quercetin for COVID-19: real-time meta analysis of 11 studies
Statistically significant lower risk is seen for ICU admission, hospitalization, recovery, cases, and viral clearance. 10 studies from 8 independent teams in 7 countries show statistically significant improvements. • Meta analysis using..
Sep 26
Ziaei et al., Food Science & Nutrition, doi:10.1002/fsn3.3715 The effect of quercetin supplementation on clinical outcomes in COVID‐19 patients: A systematic review and meta‐analysis
Systematic review and meta analysis of 5 studies, showing significantly lower mortality, ICU admission, and hospitalization with quercetin treatment.
Sep 19
Thapa et al., Makara Journal of Science, doi:10.7454/mss.v27i3.1609 In-silico Approach for Predicting the Inhibitory Effect of Home Remedies on Severe Acute Respiratory Syndrome Coronavirus-2
In Silico analysis showing that curcumin and quercetin may be beneficial for COVID-19 by binding to the main protease (Mpro), spike protein, and ACE2 receptor. Both compounds had suitable ADME properties and minimal predicted toxicity.
Sep 5
Xu et al., Proceedings of the National Academy of Sciences, doi:10.1073/pnas.2309870120 Reply to Yan et al.: Quercetin possesses a fluorescence quenching effect but is a weak inhibitor against SARS-CoV-2 main protease
In Vitro study [Yan] and associated response from the original authors [Xu], collectively showing that quercetin and echinatin had weak SARS-CoV-2 protease inhibition in SDS-PAGE assays [Xu], despite false positive FRET results from MCA-A..
Sep 5
Yan et al., Proceedings of the National Academy of Sciences, doi:10.1073/pnas.2309289120 Reframing quercetin as a promiscuous inhibitor against SARS-CoV-2 main protease
In Vitro study [Yan] and associated response from the original authors [Xu], collectively showing that quercetin and echinatin had weak SARS-CoV-2 protease inhibition in SDS-PAGE assays [Xu], despite false positive FRET results from MCA-A..
Aug 3
Micek et al., Frontiers in Nutrition, doi:10.3389/fnut.2023.1241016 Association of dietary intake of polyphenols, lignans, and phytosterols with immune-stimulating microbiota and COVID-19 risk in a group of Polish men and women
Dietary analysis of 95 adults in Poland, showing lower risk of COVID-19 with higher intake of polyphenols, lignans, and phytosterols. Results were statistically significant for total phytosterols, secoisolariciresinol, β-sitosterol, matai..
Jul 13
Mandal et al., Journal of Traditional and Complementary Medicine, doi:10.1016/j.jtcme.2023.07.004 In silico anti-viral assessment of phytoconstituents in a traditional (Siddha Medicine) polyherbal formulation – Targeting Mpro and pan-coronavirus post-fusion Spike protein
In Silico analysis of phytoconstituents of Kabasura Kudineer against SARS-CoV-2 spike protein and Mpro, showing that quercetin (Mpro) and gallic acid (spike) had the highest binding affinity and stability.
Jun 30
Sai Ramesh et al., International Journal of Biological Macromolecules, doi:10.1016/j.ijbiomac.2023.125553 Computational analysis of the phytocompounds of Mimusops elengi against spike protein of SARS CoV2 – An Insilico model
In Silico study finding that quercetin and hederagenin showed very high binding affinities for COVID-19 associated receptors MMP9 and IL6.
Jun 22
Gérain et al., Frontiers in Nutrition, doi:10.3389/fnut.2023.1137407 NASAFYTOL® supplementation in adults hospitalized with COVID-19 infection: results from an exploratory open-label randomized controlled trial
91% lower combined mortality/ICU admission (p=0.02), 89% lower ventilation (p=0.05), 89% lower ICU admission (p=0.05), and 73% higher hospital discharge (p=0.07). RCT 49 hospitalized COVID-19 patients, 25 treated with curcumin and quercetin, shower lower mortality/ICU admission and improved recovery with treatment. All patients received vitamin D. 336mg curcumin, 520mg quercetin, and 18μg vitamin D..
Jun 3
Corbo et al., Biotechnology & Biotechnological Equipment, doi:10.1080/13102818.2023.2222196 Inhibitory potential of phytochemicals on five SARS-CoV-2 proteins: in silico evaluation of endemic plants of Bosnia and Herzegovina
In Silico study of phytochemicals from 28 plants identifying hesperidin and quercetin as having the highest binding affinity for SARS-CoV-2 RdRp. The highest affinity for Mpro was observed for genistein and hesperidin, with both compounds..
Jun 2
Azmi et al., 11th International Seminar on New Paradigm and Innovation on Natural Sciences and its Application, doi:10.1063/5.0140285 Utilization of quercetin flavonoid compounds in onion (Allium cepa L.) as an inhibitor of SARS-CoV-2 spike protein against ACE2 receptors
In Silico study showing high affinity binding between the SARS-CoV-2 spike protein and quercetin, and analysis of the quercetin content of onion.
May 18
Yang et al., Frontiers in Pharmacology, doi:10.3389/fphar.2023.1188086 In silico evidence implicating novel mechanisms of Prunella vulgaris L. as a potential botanical drug against COVID-19-associated acute kidney injury
In Silico study identifying quercetin, luteolin and kaempferol as potentially protective for COVID-19 acute kidney injury.
May 15
Massimo Magro et al., Journal of Modern Biology and Drug Discovery, doi:10.53964/jmbdd.2023004 Use of Quercetin for Therapeutic Purposes in COVID-19 Infections: The Opinion of the Geriatrician Doctor
Review of the antiviral properties and potential benefits of quercetin for COVID-19.
Apr 24
Xu et al., Proceedings of the National Academy of Sciences, doi:10.1073/pnas.2301775120 Bioactive compounds from Huashi Baidu decoction possess both antiviral and anti-inflammatory effects against COVID-19
In Vitro study of compounds from Huashi Baidu (Q-14), showing dose-dependent inhibition of SARS-CoV-2 with quercetin. Authors also perform a mouse study showing that Q-14 decreases SARS-CoV-2 viral load and reduces pulmonary inflammation...
Mar 31
Wang et al., Society of Toxicology Conference, 2023 Computational Analysis of Lianhua Qingwen as an Adjuvant Treatment in Patients with COVID-19
In Silico analysis of components of Lianhua Qingwen, identifying quercetin, luteolin, wogonin, and phillyrin as potentially beneficial for COVID-19. Authors note that quercetin bound to Mpro at the same inhibitory pocket as nirmatrelvir (..
Mar 22
Ibeh et al., Informatics in Medicine Unlocked, doi:10.1016/j.imu.2023.101230 Computational studies of potential antiviral compounds from some selected Nigerian medicinal plants against SARS-CoV-2 proteins
In Silico study identifying quercetin and naringenin as potent multitarget-directed ligands for 3CLpro, PLpro, and ACE2 with favorable ADME properties.
Feb 13
Cheema et al., Reviews in Medical Virology, doi:10.1002/rmv.2427 Quercetin for the treatment of COVID-19 patients: A systematic review and meta-analysis
Systematic review and meta analysis of 6 quercetin RCTs, showing significantly lower hospitalization and ICU admission. Differences for mortality and recovery were not statistically significant.
Jan 26
Pastor-Fernández et al., Aging Cell, doi:10.1111/acel.13771 Treatment with the senolytics dasatinib/quercetin reduces SARS-CoV-2 related mortality in mice
K18-hACE2 mouse study showing reduced COVID-19 severity with quercetin and dasatinib, for both prophylaxis and early treatment.
Jan 25
Turobkulovich et al., Emergent: Journal of Educational Discoveries and Lifelong Learning Applications of quercetin for the prevention of COVID-19 in healthcare workers
96% lower mortality (p<0.0001) and 98% fewer symptomatic cases (p<0.0001). Prospective study of healthcare workers in Uzbekistan showing lower mortality and cases with quercetin prophylaxis. Very minimal details are provided, there is no baseline information, and control mortality is very high.
Jan 18
Aguado et al., bioRxiv, doi:10.1101/2023.01.17.524329 Senolytic therapy alleviates physiological human brain aging and COVID-19 neuropathology
In Vitro and animal study showing that senolytics including dasatinib + quercetin improve survival and mitigate neuropathological sequelae of SARS-CoV-2. Authors show that SARS-CoV-2 can initiate cellular senescence in the brains of COVID..
Jan 18
Din Ujjan et al., Frontiers in Nutrition, doi:10.3389/fnut.2022.1023997 The possible therapeutic role of curcumin and quercetin in the early-stage of COVID-19—Results from a pragmatic randomized clinical trial
29% improved recovery (p=0.11) and 91% improved viral clearance (p=0.05). Small RCT with 50 outpatients, 25 treated with curcumin, quercetin, and vitamin D, showing improved recovery and viral clearance with treatment. 168mg curcumin, 260mg, 360IU vitamin D3 daily for 14 days.
Jan 17
Shorobi et al., Molecules, doi:10.3390/molecules28030938 Quercetin: A Functional Food-Flavonoid Incredibly Attenuates Emerging and Re-Emerging Viral Infections through Immunomodulatory Actions
Review of the antiviral properties of quercetin and derivatives, and potential mechanisms of action.
Jan 16
Viglione et al., The Gazette of Medical Sciences, doi:10.46766/thegms.pubheal.22120905 Intravenous high dose vitamin C and ozonated saline effective treatment for Covid -19: The Evolution of Local Standard of Care
Retrospective 479 high risk outpatients in the USA treated with a protocol including intravenous vitamin C, vitamin D, zinc, quercetin, bromelain, lactoferrin, HCQ, ivermectin, ozonated saline, azithromycin, ceftriaxone, methylprednisolon..
Jan 13
Di Pierro et al., Frontiers in Pharmacology, doi:10.3389/fphar.2022.1096853 Quercetin as a possible complementary agent for early-stage COVID-19: Concluding results of a randomized clinical trial
37% improved recovery (p=0.007) and 58% improved viral clearance (p<0.0001). RCT 100 outpatients in Pakistan, 50 treated with quercetin phytosome, showing faster viral clearance and improved recovery with treatment. Patients in the treatment group were significantly younger (41 vs. 54).
Jan 12
Nguyen et al., Bioinformatics and Biology Insights, doi:10.1177/11779322221149622 The Potential of Ameliorating COVID-19 and Sequelae From Andrographis paniculata via Bioinformatics
In Silico study of components of andrographis paniculata, identifying multiple components including quercetin as promising inhibitors of SARS-CoV-2. Authors note the potential synergistic effect with multiple compounds.
Dec 12
Wu et al., Molecular Therapy, doi:10.1016/j.ymthe.2022.12.002 Treatment with Quercetin inhibits SARS-CoV-2 N protein-induced acute kidney injury by blocking Smad3-dependent G1 cell cycle arrest
Mouse study showing quercetin can significantly inhibit SARS-CoV-2 induced acute kidney injury via blocking of SARS-CoV-2 N-Smad3-mediated cell death.
Nov 29
Alavi et al., Biomedicines, doi:10.3390/biomedicines10123074 Interaction of Epigallocatechin Gallate and Quercetin with Spike Glycoprotein (S-Glycoprotein) of SARS-CoV-2: In Silico Study
In Silico study suggesting efficacy of epigallocatechin gallate and quercetin for SARS-CoV-2.
Oct 18
Cosentino et al., Journal of Clinical Medicine, doi:10.3390/jcm11206138 Early Outpatient Treatment of COVID-19: A Retrospective Analysis of 392 Cases in Italy
Retrospective 392 outpatients in Italy showing 0.2% mortality with early treatment, compared with >3% in Italy at the time. Treatment varied for individual patients and included HCQ, vitamin D, vitamin C, vitamin A, zinc, quercetin, bromh..
Aug 25
Gasmi et al., Pharmaceuticals, doi:10.3390/ph15091049 Quercetin in the Prevention and Treatment of Coronavirus Infections: A Focus on SARS-CoV-2
Review of the potential benefits of quercetin for COVID-19, including inhibitory effects on several stages of the viral life cycle, antioxidant, anti-inflammatory, and immunomodulatory effects, and synergistic effects with other treatments.
Aug 10
Chellasamy et al., Journal of King Saud University - Science, doi:10.1016/j.jksus.2022.102277 Docking and molecular dynamics studies of human ezrin protein with a modelled SARS-CoV-2 endodomain and their interaction with potential invasion inhibitors
In Silico study of SARS-CoV-1&2 endodomains and ezrin docking, identifying ivermectin, quercetin, calcifediol, calcitriol, selamectin, and minocycline as potential therapeutic drugs with strong ezrin binding which may restrict viral endod..
Jun 16
Ortore et al., International Journal of Translational Medicine, doi:10.3390/ijtm2020022 Evaluation of the Clinical Effects of an Antiviral, Immunostimulant and Antioxidant Phytotherapy in Patients Suffering from COVID-19 Infection: An Observational Pilot Study
Retrospective case series of 240 patients in Italy in 2020, up to 96 years old, showing no mortality and 1.6% hospitalization with early treatment including vitamin C, quercetin, and green tea and red wine polyphenols. The formulation was..
May 20
Shah et al., medRxiv, doi:10.1101/2022.05.16.22275074 Jinhua Qinggan Granules for Nonhospitalized COVID-19 Patients: a Double-Blind, Placebo-Controlled, Randomized Controlled Trial
81% greater improvement (p<0.0001) and 8% worse viral clearance (p=0.48). RCT 300 outpatients in China, showing improved recovery with Jinhua Qinggan treatment, but no significant difference in viral clearance or radiographic findings. Jinhua Qinggan includes quercetin, rutin, luteolin, wogonin, myricetin, urso..
May 15
Rizky et al., Life Research, doi:10.53388/life2022-0205-302 The pharmacological mechanism of quercetin as adjuvant therapy of COVID-19
Review of in silico and clinical evidence supporting the use of quercetin for COVID-19.
May 1
Khan et al., Frontiers in Pharmacology, doi:10.3389/fphar.2022.898062 Oral Co-Supplementation of Curcumin, Quercetin, and Vitamin D3 as an Adjuvant Therapy for Mild to Moderate Symptoms of COVID-19—Results From a Pilot Open-Label, Randomized Controlled Trial
33% improved recovery (p=0.15) and 50% improved viral clearance (p=0.009). RCT 50 COVID+ outpatients in Pakistan, 25 treated with curcumin, quercetin, and vitamin D, showing significantly faster viral clearance, significantly improved CRP, and faster resolution of acute symptoms (p=0.154). 168mg curcumin, 260mg ..
Apr 29
Imran et al., Antioxidants, doi:10.3390/antiox11050876 The Therapeutic and Prophylactic Potential of Quercetin against COVID-19: An Outlook on the Clinical Studies, Inventive Compositions, and Patent Literature
Review of the evidence supporting the use of quercetin for COVID-19 from clinical studies and patents.
Jan 21
Goc et al., European Journal of Microbiology and Immunology, doi:10.1556/1886.2021.00022 Inhibitory effects of specific combination of natural compounds against SARS-CoV-2 and its Alpha, Beta, Gamma, Delta, Kappa, and Mu variants
In Vitro study testing combinations of plant extracts and micronutrients with several variants of SARS-CoV-2. A combination of vitamin C, N-acetylcysteine, curcumin, quercetin, resveratrol, theaflavin, naringenin, baicalin, and broccoli e..
Jan 4
Rondanelli et al., Life, doi:10.3390/life12010066 Promising Effects of 3-Month Period of Quercetin Phytosome® Supplementation in the Prevention of Symptomatic COVID-19 Disease in Healthcare Workers: A Pilot Study
93% fewer symptomatic cases (p=0.04). RCT 120 healthcare workers, 60 treated with quercetin phytosome, showing lower risk of cases with treatment. Quercetin phytosome 250mg twice a day.
Dec 28
Munafò et al., Research Square, doi:10.21203/ Quercetin and Luteolin Are Single-digit Micromolar Inhibitors of the SARS-CoV-2 RNA-dependent RNA Polymerase
In Vitro and In Silico study showing quercetin and luteolin inhibiting SARS-CoV-2 RNA-dependent RNA polymerase (RdRp).
Dec 14
Singh et al., Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, doi:10.1016/j.bbadis.2021.166322 The spike protein of SARS-CoV-2 virus induces heme oxygenase-1: Pathophysiologic implications
In Vitro study transfecting SARS-CoV-2 viral spike protein in kidney cell lines, showing syncytia formation and upregulation of the cytoprotective gene HO-1, and that quercetin, which induces HO-1, can reduce syncytia formation. Authors c..
Dec 8
Fazio et al., Medical Science Monitor, doi:10.12659/MSM.935379 Retrospective Study of Outcomes and Hospitalization Rates of Patients in Italy with a Confirmed Diagnosis of Early COVID-19 and Treated at Home Within 3 Days or After 3 Days of Symptom Onset with Prescribed and Non-Prescribed Treatments Between November 2020 and August 2021
Retrospective 158 COVID-19 patients in Italy treated with hesperidin, quercetin, indomethacin, aspirin, omeprazole, azithromycin, LMWH, and betamethasone (treatment specific for each patient), showing significantly lower hospitalization a..
Dec 2
Shohan et al., European Journal of Pharmacology, doi:10.1016/j.ejphar.2021.1746158 The therapeutic efficacy of quercetin in combination with antiviral drugs in hospitalized COVID-19 patients: A randomized controlled trial
86% lower mortality (p=0.24) and 32% faster recovery (p=0.04). Small RCT with 60 severe hospitalized patients in Iran, 30 treated with quercetin, showing shorter time until discharge. All patients received remdesivir or favipiravir, and vitamin C, vitamin D, famotidine, zinc, dexamethasone, and magne..
Nov 14
Bahun et al., Food Chemistry, doi:10.1016/j.foodchem.2021.131594 Inhibition of the SARS-CoV-2 3CLpro main protease by plant polyphenols
In Silico and In Vitro study of plant polyphenols identifying quercetin, curcumin, ellagic acid, epigallocatechin gallate, and resveratrol as SARS-CoV-2 3CLpro inhibitors with IC50 between 11.8µM and 23.4µM. Real-time binding was analyzed..
Sep 29
Şimşek et al., Journal of Molecular Graphics and Modelling, doi:10.1016/j.jmgm.2021.108038 In silico identification of SARS-CoV-2 cell entry inhibitors from selected natural antivirals
In Silico study identifying quercetin derivatives as SARS-CoV-2 spike protein, ACE2, and neuropilin inhibitors.
Sep 1
Zupanets et al., Zaporozhye Med. J., doi:10.14739/2310-1210.2021.5.231714 Quercetin effectiveness in patients with COVID-19 associated pneumonia
29% improved recovery (p=0.5). RCT 200 patients in Ukraine, 99 treated with IV quercetin/polyvinylirolidone followed by oral quercetin/pectin, showing improved recovery with treatment.
Jul 6
Margolin et al., Journal of Evidence-Based Integrative Medicine, doi:10.1177/2515690X211026193 20-Week Study of Clinical Outcomes of Over-the-Counter COVID-19 Prophylaxis and Treatment
94% fewer cases (p=0.003). Retrospective 113 outpatients, 53 (patient choice) treated with zinc, quercetin, vitamin C/D/E, l-lysine, and quina, showing lower cases with treatment. Results are subject to selection bias and limited information on the groups is provid..
Jun 15
Kandeil et al., Pathogens, doi:10.3390/pathogens10060758 Bioactive Polyphenolic Compounds Showing Strong Antiviral Activities against Severe Acute Respiratory Syndrome Coronavirus 2
Vero E6 In Vitro study showing curcumin, hesperidin, and quercetin significantly inhibited SARS-CoV-2 replication, and In Silico analysis with promising Mpro and spike docking results.
Jun 8
Di Pierro et al., International Journal of General Medicine, doi:10.2147/IJGM.S318720 Possible Therapeutic Effects of Adjuvant Quercetin Supplementation Against Early-Stage COVID-19 Infection: A Prospective, Randomized, Controlled, and Open-Label Study
86% lower mortality (p=0.25), 94% lower ICU admission (p=0.006), and 68% lower hospitalization (p=0.003). RCT 152 outpatients in Pakistan, 76 treated with quercetin phytosome, showing lower mortality, ICU admission, and hospitalization with treatment.
Apr 8
Aguilar et al., Journal of Advances in Medical and Pharmaceutical Sciences, doi:10.9734/jamps/2021/v23i330222 Oral Quercetin in Adult Patients as a Potential Nutraceutical against Coronavirus Disease 2019 (COVID-19)
Prospective study of 52 patients treated with quercetin. There was no control group.
Jan 19
Onal et al., Turk. J. Biol., 45:518-529 (date from preprint) Treatment of COVID-19 patients with quercetin: a prospective, single center, randomized, controlled trial
94% lower ICU admission (p=0.39) and 78% higher hospital discharge (p=0.1). RCT 447 moderate-to-severe hospitalized patients in Turkey, 52 treated with quercetin, bromelain, and vitamin C, showing no statistically significant difference in clinical outcomes. NCT04377789.
Nov 16
Arslan et al., SSRN, doi:10.2139/ssrn.3682517 Synergistic Effect of Quercetin and Vitamin C Against COVID-19: Is a Possible Guard for Front Liners
92% fewer cases (p=0.03). Small prophylaxis RCT with 113 patients showing fewer cases with quercetin + vitamin C + bromelain prophylaxis. NCT04377789. Note that this paper disappeared from SSRN without explanation.
Oct 9
Derosa et al., Phytotherapy Research, doi:10.1002/ptr.6887 A role for quercetin in coronavirus disease 2019 (COVID-19)
Review noting that quercetin has a theoretical, but significant, capability to interfere with SARS-CoV-2 replication, with results showing this to be the fifth best compound out of 18 candidates.
Jun 19
Biancatelli et al., Frontiers in Immunology, doi:10.3389/fimmu.2020.01451 Quercetin and Vitamin C: An Experimental, Synergistic Therapy for the Prevention and Treatment of SARS-CoV-2 Related Disease (COVID-19)
Review of the evidence for the use of vitamin C and quercetin both for prophylaxis in high-risk populations and for the treatment of COVID-19 patients.
Apr 24
Sekiou et al., ChemRxiv, doi:10.26434/chemrxiv.12181404.v1 In-Silico Identification of Potent Inhibitors of COVID-19 Main Protease (Mpro) and Angiotensin Converting Enzyme 2 (ACE2) from Natural Products: Quercetin, Hispidulin, and Cirsimaritin Exhibited Better Potential Inhibition than Hydroxy-Chloroquine Against COVID-19 Main Protease Active Site and ACE2
In Silico study of natural compounds identifying quercetin, curcumin, hispidulin, cirsimaritin, sulfasalazine, and artemisin as potential compounds that inhibit SARS-CoV-2.
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