Note that in a larger set of 77 human coronaviruses, a serine (S) in P4 is very common ( pro active site
While some polyphenol-rich extracts, such as grape seed extract, have shown high tolerability in animal and short-term human studies, the safety of long-term, high-dose intake across a broad population spectrum remains to be confirmed (122, 123)
This matters because those reports do not all answer the same question
36 It was postulated that the vitreous gel normally impedes diffusion of oxygen from the region adjacent to the retina where oxygen is high owing to proximity to retinal vessels
Given the short half-life, twice-daily dosing provides additional exposure compared to once-daily protocols at the same total dose
Glutathione has a documented safety profile in the clinical literature