Quercetin is a flavonoid found in capers, peppers, and onions. It has been identified as a zinc ionophore which is a compound that can transport zinc ions across a cell membrane. In this clip, Dr. Rhonda Patrick discusses quercetin's identified antiviral activity against SARS-CoV-1 and its role in zinc transport.
This clip was taken from the COVID-19 Q&A #1 with Rhonda Patrick found at https://youtu.be/Nfp4X4O87DQ
Rhonda: The question is, can you talk about quercetin's role as a zinc ionophore? So quercetin is a flavonoid, it's found in onions, green tea, apples, berries. It's found in other plants like ginkgo biloba, St. John's wort, buckwheat tea. Quercetin has been reported to block the entry of SARS-CoV-2, the virus that caused the original SARS outbreak in host cells. And so, this was in cells in a Petri dish. The cytotoxicity of quercetin is very low. It's already an FDA-approved drug ingredient. People can take it as a supplement. It has not been clinically tested in SARS-CoV-2. Clinical trials, or at least one clinical trial is beginning in a collaborative effort between Canada and China with outcomes expected in around four months.
So there was a publication that involved the screening of old drugs to sort of repurpose them against COVID-19. And based on that publication, there was a genome similarity. SARS is the closest virus to the SARS-CoV-2 and followed by MERS and other human coronavirus diseases. Data mining identified 34 COVID-2019 related genes and 24 disease-related pathways. Using drug prioritization algorithms, researchers identified 78 drugs to repurpose. There was manual filtering based on clinical knowledge and a variety of other screening methods, but quercetin was included in this group. In another virtual screening of Chinese herbal medicines, quercetin was also predicted as a potentially useful drug to repurpose against the SARS-CoV-2 virus. The literature is pretty supportive of quercetin having antiviral capacities when it's cultured with targeted cells and a broad spectrum of pathogens, including rhinoviruses, adenoviruses, and coronaviruses.
Another in vitro study with cultured cells found that quercetin does seem to have zinc ionophore activity. So polyphenols such as quercetin as well as EGCG can transport zinc cations across the plasma membrane independently of plasma membrane zinc transporters. Zinc inhibits the action of RNA-dependent RNA polymerase, as mentioned earlier, a key enzyme in the reproduction of RNA viruses. So that's pretty much what the current literature says on quercetin as a zinc ionophore and the limited amount of literature showing it does have antiviral activity, particularly has been shown to have antiviral activity against the SARS-CoV-1 virus.
An infectious disease caused by the novel coronavirus SARS-CoV-2. COVID-19, or coronavirus disease 2019, was first identified in Wuhan, China, in late 2019. The disease manifests primarily as a lower respiratory illness, but it can affect multiple organ systems, including the cardiovascular, neurological, gastrointestinal, and renal systems. Symptoms include fever, cough, fatigue, shortness of breath, and loss of smell and taste. Some infected persons, especially children, are asymptomatic. Severe complications of COVID-19 include pneumonia, sepsis, acute respiratory distress syndrome, kidney failure, multiple organ dysfunction syndrome, and cytokine storm. Treatments currently involve symptom management and supportive care. Mortality varies by country and region, but approximately 6 percent of people living in the United States who are diagnosed with COVID-19 expire. 1
Any of a group of complex proteins or conjugated proteins that are produced by living cells and act as catalyst in specific biochemical reactions.
Flavonoid are widely distributed in plants, fulfilling many functions. Flavonoids have been shown to have a wide range of biological and pharmacological activities in animal, human, and in-vitro studies. Examples include anti-allergic, anti-inflammatory, antioxidant, antimicrobial, anti-cancer, and anti-diarrheal activities.
Experiments that are performed using cells or microorganisms outside of their normal biological context and are often done in a test tube or petri dish.
In general, anything that can produce disease. Typically, the term is used to describe an infectious agent such as a virus, bacterium, prion, fungus, or other microorganism.
A class of chemical compounds produced in plants in response to stressors. Polyphenols contribute to the bitterness, astringency, color, flavor, and fragrance of many fruits and vegetables. They often serve as deterrents to insect or herbivore consumption. When consumed in the human diet, polyphenols exert many health benefits and may offer protection against development of cancers, cardiovascular diseases, diabetes, osteoporosis, and neurodegenerative diseases. Dietary sources of polyphenols include grapes, apples, pears, cherries, and berries, which provide as much as 200 to 300 mg polyphenols per 100 grams fresh weight.
A bioactive compound found in many edible plants. Quercetin demonstrates a wide range of health-promoting characteristics, including antioxidant, anti-inflammatory, and anti-cancer properties. It scavenges reactive oxygen and nitrogen species, inhibits activation of the proinflammatory molecule nuclear factor kappa B (NF-κB), and downregulates the inflammatory response of macrophages. When used in conjunction with the chemotherapy drug dasatinib, quercetin shows promise as a senolytic (anti-aging) compound, effectively clearing senescent cells and promoting improvements in a variety of age-related diseases. Dietary sources of quercetin include onions (most abundant), apples, berries, leafy vegetables, herbs, spices, legumes, tea, and cocoa.
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