Ethylene glycol (HO—CH₂—CH₂—OH) is a major component of antifreeze. If ingested, it is first converted to HOOC—CHO (oxoethanoic acid) and then to HOOC—COOH (oxalic acid), which is toxic.
b. The treatment for the ingestion of ethylene glycol is an intravenous solution of ethanol. How might this help prevent toxic levels of oxalic acid in the body?

Question

Ethylene glycol (HO—CH₂—CH₂—OH) is a major component of antifreeze. If ingested, it is first converted to HOOC—CHO (oxoethanoic acid) and then to HOOC—COOH (oxalic acid), which is toxic.

b. The treatment for the ingestion of ethylene glycol is an intravenous solution of ethanol. How might this help prevent toxic levels of oxalic acid in the body?

Accepted Answer

Hi, everybody. Let's take a look at this next problem. It says methanol ch 30 is a toxic substance that can lead to blindness or death if ingested, it is metabolized in the liver by the same enzyme that metabolizes ethanol. The toxic metabolites of methanol are formaldehyde H cho and formic acid H coo H the administration of an intravenous ethanol solution is used as a treatment for ethanol poisoning. How could this method help in preventing the toxic effects of methanol ingestion? Well, the key here is to think about what makes methanol toxic. It's the fact that its metabolites are toxic. So if we think of this process, we have methanol, I'm going to abbreviate it. M capital me and capital O capital H. Methanol gets converted into formaldehyde and this is by in the body. The end, I'm alcohol dehydrogenase or A DH. So I'll draw an arrow going to formaldehyde with a DH on top of it and then the formaldehyde layer gets converted to formic acid. So these two metabolites are toxic. And another important thing to notice is that alcohol dehydrogenase, we're told also metabolizes ethanol. So if what makes methanol toxic is the action of a DH. But a DH can also act on ethanol and produce nontoxic metabolites. Then administering uh intravenous ethanol, essentially out competes the methanol for the enzyme. So as we just pump all this ethanol in there, it essentially uses up all of the active sites available on that. A DH in the body. And this strategy is called competitive enzyme inhibition. We're inhibiting the ability of the enzyme to metabolize methanol by just flooding its active sites with an alternate substrate. And note that since ethanol is what this enzyme usually acts on the ethanol actually has a higher affinity or the enzyme has a higher affinity for ethanol than methanol. So this should be pretty successful if there's plenty of ethanol around the enzyme is going to bind that before binding methanol. And what happens then is that the methanol rather than getting converted into these toxic metabolites is eliminated from the body without conversion. So the liver takes care of that without producing or without the production of the toxic substances. So I drew an arrow going from administration of IV ethanol up to that original reaction and showing that methanol gets eliminated from the body without being converted into formaldehyde and formic acid. So this is the reason why treating someone with intravenous ethanol solution can help prevent the to prevent the toxic effects of methanol ingestion. It uses up ethanol, uses up the active sites on a DH available in the body, meaning that methanol gets eliminated from the body without being converted into formaldehyde and formic acid, which are the toxic metabolites of methanol. See you in the next video.

Verified video answer for a similar problem:

Key Concepts

Metabolism of Ethylene Glycol

Ethanol as an Antidote

Toxicity of Oxalic Acid