Vitamin C inhibits SARS coronavirus-2 main protease essential for viral replication
et al., bioRxiv, doi:10.1101/2021.05.02.442358, May 2021
Vitamin C for COVID-19
6th treatment shown to reduce risk in
September 2020, now with p = 0.00000002 from 75 studies, recognized in 22 countries.
No treatment is 100% effective. Protocols
combine treatments.
6,200+ studies for
200+ treatments. c19early.org
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In SIlico and in vitro study showing that vitamin C inhibits SARS-CoV-2 3CLpro. Authors note that the different clinical results may be explained in part by the widely varying dosages used, and they conclude that vitamin C and/or derivatives may become an important treatment for COVID-19 and other viral infections.
17 preclinical studies support the efficacy of vitamin C for COVID-19:
Vitamin C has been identified by the European Food Safety Authority (EFSA) as having sufficient evidence for a causal relationship between intake and optimal immune system function15-17.
Vitamin C plays a key role in the immune system, supporting the production and function of leukocytes, or white blood cells, which defend against infection and disease, including the production of lymphocytes, which make antibodies, and enhancing phagocytosis, the process by which immune system cells ingest and destroy viruses and infected cells.
Vitamin C is an antioxidant, protecting cells from damage caused by free radicals.
Vitamin C inhibits SARS-CoV-2 3CLpro7,11, inhibits SARS-CoV-2 infection by reducing ACE2 levels in a dose-dependent manner12, and may limit COVID-19 induced cardiac damage by acting as an antioxidant and potentially reducing the reactive oxygen species (ROS) production induced by the spike protein that contributes to the activation of profibrotic pathways9.
Vitamin C reduces inflammation, oxidative stress, and NETosis, supporting immune function and vascular protection18.
Intracellular levels of vitamin C decline during COVID-19 hospitalization suggesting ongoing utilization and depletion of vitamin C19.
Threonic acid, a metabolite of vitamin C, is lower in mild and severe cases, consistent with increased need for and metabolization of vitamin C with moderate infection, but more limited ability to produce threonic acid in severe infection due to depletion or existing lower levels of vitamin C20.
Symptomatic COVID-19 is associated with a lower frequency of natural killer (NK) cells, and vitamin C has been shown to improve NK cell numbers and functioning21,22.
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Van Tin et al., Spike Protein of SARS-CoV-2 Activates Cardiac Fibrogenesis through NLRP3 Inflammasomes and NF-κB Signaling, Cells, doi:10.3390/cells13161331.
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Moatasim et al., Potent Antiviral Activity of Vitamin B12 against Severe Acute Respiratory Syndrome Coronavirus 2, Middle East Respiratory Syndrome Coronavirus, and Human Coronavirus 229E, Microorganisms, doi:10.3390/microorganisms11112777.
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Đukić et al., Inhibition of SARS-CoV-2 Mpro with Vitamin C, L-Arginine and a Vitamin C/L-Arginine Combination, Frontiers in Bioscience-Landmark, doi:10.31083/j.fbl2801008.
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Zuo et al., Vitamin C promotes ACE2 degradation and protects against SARS‐CoV‐2 infection, EMBO reports, doi:10.15252/embr.202256374.
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Hajdrik et al., In Vitro Determination of Inhibitory Effects of Humic Substances Complexing Zn and Se on SARS-CoV-2 Virus Replication, Foods, doi:10.3390/foods11050694.
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Goc et al., Inhibitory effects of specific combination of natural compounds against SARS-CoV-2 and its Alpha, Beta, Gamma, Delta, Kappa, and Mu variants, European Journal of Microbiology and Immunology, doi:10.1556/1886.2021.00022.
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17.
EFSA, Scientific Opinion on the substantiation of health claims related to vitamin C and protection of DNA, proteins and lipids from oxidative damage (ID 129, 138, 143, 148), antioxidant function of lutein (ID 146), maintenance of vision (ID 141, 142), collagen formation (ID 130, 131, 136, 137, 149), function of the nervous system (ID 133), function of the immune system (ID 134), function of the immune system during and after extreme physical exercise (ID 144), non-haem iron absorption (ID 132, 147), energy-yielding metabolism (ID 135), and relief in case of irritation in the upper respiratory tract (ID 1714, 1715) pursuant to Article 13(1) of Regulation (EC) No 1924/2006, EFSA Journal, doi:10.2903/j.efsa.2009.1226.
18.
Xie et al., The role of reactive oxygen species in severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) infection-induced cell death, Cellular & Molecular Biology Letters, doi:10.1186/s11658-024-00659-6.
19.
Boerenkamp et al., Low Levels of Serum and Intracellular Vitamin C in Hospitalized COVID-19 Patients, Nutrients, doi:10.3390/nu15163653.
20.
Albóniga et al., Differential abundance of lipids and metabolites related to SARS-CoV-2 infection and susceptibility, Scientific Reports, doi:10.1038/s41598-023-40999-5.
Malla et al., 3 May 2021, preprint, 9 authors.
In vitro studies are an important part of preclinical research, however results may be very different in vivo.
Vitamin C Binds to SARS Coronavirus-2 Main Protease Essential for Viral Replication
doi:10.1101/2021.05.02.442358
There is an urgent need for anti-viral agents that treat and/or prevent Covid-19 caused by SARS-Coronavirus (CoV-2) infections. The replication of the SARS CoV-2 is dependent on the activity of two cysteine proteases, a papain-like protease, PL-pro, and the 3C-like protease known as main protease Mpro or 3CLpro. The shortest and the safest path to clinical use is the repurposing of drugs with binding affinity to PLpro or 3CLpro that have an established safety profile in humans. Several studies have reported crystal structures of SARS-CoV-2 main protease in complex with FDA approved drugs such as those used in treatment of hepatitis C. Here, we report the crystal structure of 3CLpro in complex Vitamin C (L-ascorbate) bound to the protein's active site at 2.5 Ångstrom resolution. The crystal structure of the Vitamin C 3CLpro complex may aid future studies on the effect of Vitamin C not only on the coronavirus main protease but on related proteases of other infectious viruses.
Supplementary Material Expression. The CoV-2 3CLpro sequence was synthetized (GenScript) for optimized expression in E. coli according to sequence information published previously (Zhang, Lin, Sun, et al., 2020) . In short, the N-terminus of 3CLpro is fused to glutathione-S-transferase (GST). It further has a 6-His tag at the c-terminus. The N-terminal GST will be autocatalytically cleaved off after expression due to an engineered 3CLpro cleavage sequence. Although the His tag can be cleaved off by a PreScission protease, the tag did not interfere with crystallization and consequently was left on. Overexpression and protein purification protocols were modified from previous reports. E. coli were grown to 0.8 OD 600 at 37 o in terrific broth. Expression was induced by 1 mmol/L IPTG at 25 o C. After 3 h of expression, the culture was induced a second time (1 mmol/L IPTG), and shaken overnight at 20 o C. The yield is about 80 mg for a 6 L culture. Cells were resuspended in lysis buffer (20mM Tris Base, 150 mmol/L NaCl, pH 7.8.). After lysis of the bacterial cells, debris was centrifuged at 50,000 g for 1 hour. The lysate was let stand at room temperature for 3 h (overnight is also possible). After this, the lysate was pumped through a column containing 15 mL of Talon Cobalt resin (TAKARA). The resin was washed without using imidazole using a wash cycle consisting of low salt (20 mmol/L Tris Base, 50 mmol/L NaCl, pH 7.8), high salt (20 mmol/L Tris Base, 1 mol/L NaCl, pH 7.8) and..
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