Glycyrrhizin, an active component of liquorice roots, and replication of SARS-associated coronavirus

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Glycyrrhizin, an active component of liquorice roots, and replication of SARS-associated coronavirus

The outbreak of SARS warrants the search for antiviral compounds to treat the disease. At present, no specific treatment has been identified for SARS-associated coronavirus infection. We assessed the antiviral potential of ribavirin, 6-azauridine, pyrazofurin, mycophenolic acid, and glycyrrhizin against two clinical isolates of coronavirus (FFM-1 and FFM-2) from patients with SARS admitted to the clinical centre of Frankfurt University, Germany. Of all the compounds, glycyrrhizin was the most active in inhibiting replication of the SARS-associated virus. Our findings suggest that glycyrrhizin should be assessed for treatment of SARS.

 

[YippeeKi YOW !!]

Glycyrrhizin, an active component of liquorice roots, and replication of SARS-associated coronavirus

And damn, wouldn't you know .... I've been taking deglycyrrhizinated licorice root (DGL) the last couple of weeks for stomach ache ..... useless for COVID, but great for tum troubles ....

A quick warning: the glycyrrhizin in licorice is the component that causes increases in blood pressure, sometimes dramatic and occasionally fatal, so use with some caution, or do a quick google and see what the usage restrictions are ...

 

[Hip]

Having spent a lot of time reading antiviral studies, looking at this one, I cannot see how glycyrrhizin would have any useful clinical effect against coronavirus, unless you injected massive doses of glycyrrhizin.

The glycyrrhizin EC50 value in the study seems far too high, at 300 mg/liter. The EC50 is the concentration which inhibits viral replication by 50% in a cell line in vitro.

To have a viable antiviral effect, you typically need reach blood concentrations that are at least around 5 times the EC50, so in this case you need a glycyrrhizin blood concentrations of 5 * 300 = 1,500 mg per liter = 1.5 grams per liter.

But because the blood plasma protein binding of glycyrrhizin is 80%, that means 80% of the glycyrrhizin in the blood is lost to protein binding, and only 20% is left. So to compensate for this loss, you would need to increase your concentration by 100% / 20% = 5 times. So we need a glycyrrhizin blood concentration of 5 * 1.5 = 7.5 grams per liter.

Now if we assume about 40 liters of fluids in the body, to achieve a concentration of 7.5 grams per liter you would need a dose of 40 * 7.5 = 300 grams of glycyrrhizin!

That seems far to high to be clinically practicable.



And remember that glycyrrhizin oral bioavailability is pretty much zero, so orally almost no glycyrrhizin is absorbed. So you would need to use glycyrrhizin injections. Glycyrrhizin injections are used in Japan for antiviral treatment of hepatitis.

The Japanese injectable glycyrrhizin product is called "stronger neo-minophagen C", and consists of a 20 ml vial containing 40 mg of glycyrrhizin. 1 Normal dose of this injection is 40 ml daily (= 80 mg), but up to 100 ml daily (= 200 mg) has been used. 1 But 200 mg is much, much smaller than the 300 grams needed for coronavirus.

 

[IThinkImTurningJapanese]

Now if we assume about 40 liters of fluids in the body, to achieve a concentration of 7.5 grams per liter you would need a dose of 40 * 7.5 = 300 grams of glycyrrhizin!

That seems far to high to be clinically practicable.

Indeed,

However, although high doses of glycyrrhizin have been used in clinical trials, this compound had few toxic effects compared with the other regimens, and the drug was reported to be clinically effective.