a bonobo humanity?

So we start with a closer look at glutathione, and its backbone amino acid chain, including the amino acid cysteine. Cysteine has the formula HO₂CCH(NH₂)CH₂SH. The thiol sub-chain (SH) is important because it can bind to another form of the molecule, with S binding to S (oxidised form) rather than binding to H (reduced form) as here. So, as Dr Seheult explains, if you have two glutathiones, in this reduced form (2GSH), oxidised via hydrogen peroxide (H₂O₂), you will create a bond (GS-SG) between the two oxidised glutathiones, together with water. This happens in the oxidisation processes in our cells.

Seheult next mentions ADAMTS13, which is also known as von Willibrand factor-cleaving protease, so it’s a zinc-containing enzyme. VWF polymerises via disulphide bonds, and ADAMTS13 can help in disrupting that process, I think. Seheult diverts us by mentioning the disulphide bonds that connect the spiral strands of keratin in hair. A ‘perm’ reduces the molecular structure, breaking the disulphide bonds, so that the individual strands can be straightened, or made more curly, after which ‘you neutralise the perm agent’?? via H₂O₂, allowing disulphide bonds to re-form keeping the new hair structure in place. That was almost interesting.

So what can we do to assist these glutathione-based processes in relieving oxidative stress? This is apparently where N-Acetylcysteine (NAC) comes in. This molecule, which is ‘the N-acetyl derivative of the natural amino acid L-cysteine’, is ‘an antioxidant and disulphide breaking agent’, according to a 2018 review article in the Journal of Free Radical Research (not a political journal). So NAC is a reducing agent, which, like cysteine, has an SH bond. It breaks disulphide bonds and adds hydrogen, reducing viscosity. NAC has been used as a mucolytic inhalant, and as an agent against tylenol (paracetamol) overdose. How this last effect works is complex and I’ll try to comprehend it.

As Seheult explains it, NAC would act on the metabolite of paracetamol in situations of overdose. In such cases the liver metabolises paracetamol via an alternative pathway, by means of the toxic metabolite NAPQI, which depletes the liver’s glutathione. NAC replenishes the glutathione, but I won’t try to analyse the mechanism here. The main point is that NAC’s glutathione-boosting effects may have potential in dealing with Covid-19 symptoms. According to the above-mentioned review article, glutathione depletion is related to oxidative stress associated with a wide range of illnesses and pathologies, as well as in general ageing. So, a 1997 study in Italy looked at H1N1 flu and NAC treatment in a randomised, double-blind trial of 262 individuals of both sexes, most of them suffering from non-respiratory chronic degenerative diseases. They were divided into a placebo group and a NAC tablet group for a period of six months. No difference was found in both groups contracting the virus, but the majority of the placebo group (79%) came down with symptomatic forms, compared to only 25% of the treatment group, a significant difference. The study concluded that NAC treatment ‘appears to provide a significant attenuation of influenza and influenza-like episodes, especially in elderly high-risk individuals.’

So, recognising that this update is 2-3 months old now, I went online to see if NAC treatment is being used, or more comprehensive trials are being undertaken, as I note that, though case-rates are still disturbingly high, especially in the USA, death-rates are somewhat reduced.

An article from NCBI (the National Center for Biotechnology Information), which post-dates update 69 by a couple of weeks, presents only a hypothesis:

that NAC could act as a potential therapeutic agent in the treatment of COVID-19 through a variety of potential mechanisms, including increasing glutathione, improving T cell response, and modulating inflammation.

However, it didn’t seem as if any effective clinical trials focusing specifically on Covid-19 had been completed at the time of the article. A much more recent article (July 14) in Future Medicine (not such a promising name, given the urgency), presents more biochemical detail of NAC’s action, along with the anticoagulant heparin, and mentions ongoing clinical trials, but not specific results. It also mentions NAC treatment as a preventive for frontline ICU workers and general healthcare workers. It may be that such treatment is already being applied.

So, returning to update 69, Seheult cites another article from 2010 in Biochemical Pharmacology which showed that NAC inhibited viral replication (here the virus was H5N1) and reduced inflammatory cytokines, and again they suggested it as a potential treatment in the case of future influenza pandemics. Another small trial suggested some limited efficacy for NAC in the treatment of acute respiratory distress syndrome (ARDS).

So on it goes. A 2018 article found that ‘[NAC] improves oxidative stress and inflammatory response in patients with community acquired pneumonia [CAP]’. This oxidative stress reduction may be more important for Covid-19 cases because of the possibility of thrombosis due to the effect on VWF. A 2013 study found a significant decrease in a number of coagulation factors with NAC treatment. Of course, with this blood-thinning facility, NAC should not be used for patients with increased bleeding risk during or resulting from surgery. In any case I note that NAC is on the WHO list of most safe drugs or treatments.

And there are more studies. Another 2018 study found that NAC could reverse cerebral injury from strokes exacerbated by diabetes. The study concludes that ‘the diabetic blood and brain become more susceptible to platelet activation and thrombosis’, and that NAC appears to offer protection against the risk of stroke. The study’s explanation of the process here gives me an opportunity for further revision:

[NAC protects against stroke] by altering both systemic and vascular prothrombotic responses via enhancing platelet GSH, and GSH-dependent MG elimination, as well as correcting levels of antioxidants such as SOD1 and GPx-1.

So that’s platelet glutathione, and glutathione-dependent methylglyoxal, and the antioxidants mentioned are superoxide dismutase 1 and glutathione peroxidase 1. The ScienceDirect website does an amazing job of informing us about every known aspect of molecular biochemistry, just saying. Its material on glutathione and its catalysis is exhaustive and exhausting. And it looks as though the silver lining to the tragedy of Covid-19 may be a spike in further research into this and other essential elements of the molecular basis of immune systems.

Dr Seheult goes on to cite one more study, which found that ‘NAC administration promotes lysis of arterial thrombi that are resistant to conventional approaches…’, principally by acting on VWF, and that it is even more effective in combination with ‘a nonpeptidic GpIIa/IIIb (glycoprotein) inhibitor’, with no observed worsening of symptoms or outcome vis-a-vis normal haemostasis.

So I’ll end this piece wondering how things are going with NAC and other applications to reduce both respiratory and thrombotic symptoms in regions where the virus continues to be spread through a mixture of government, business and personal irresponsibility and stupidity. The battle to keep people alive and relatively healthy will, I think, ultimately win over the stupidity of some, but at a terrible and tragic cost. Vaccines are in the offing, but fear, indifference and ignorance will probably have the most adverse influence on their effectiveness.

References

Coronavirus Pandemic Update 69: “NAC” Supplementation and COVID-19 (N-Acetylcysteine)

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7261085/

https://www.futuremedicine.com/doi/10.2217/fmb-2020-0074

https://www.sciencedirect.com/science/article/pii/S0304416512002735

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/methylglyoxal