|English: Dimethyl disulfide 日本語: Dimethyl disulfide（ジメチルスルフィド） (Photo credit: Wikipedia)|
So what is the cause of the odor?
For the non-chemist reader a thiol is an organic molecule similar to alcohol except that sulfur takes the place of oxygen. Hence the smell. For the readers who are familiar with chemistry it is precisely the following:
- dimethyl sulfide, dimethyl disulfide
- dimethyl sulfoxide, bis-(methylthio)methane
- S-methyl thioacrylate
- dimethyl sulphone
This is a blog about pharmaceuticals. So here is where thiols tie-in. It appears that thiols are important parts of Acitve Pharmaceutical Ingredients (APIs). My first encounter with a thiol was working with nizatidine. I often described it as smelling like a locker room and tasting like yak vomit. There are other commonly used drugs that contain thiol groups. Examples are:
- D-peniciliamine (Treats Rheumatoid Arthritis)
- Captopril (Treatment of hypertension)
- Gold Sodium Thiomalate (Treats Rheumatoid Arthritis)
- Pyritinol (Dietary supplement and Treats Rheumatoid Arthritis)
Thiols are chelatng agents. They are often referred to as mercaptins. They have many industrial uses and laboratory uses. As therapy, Dimercaptosuccinic Acid is indicated for the treatment of lead poisoning in children with lead blood levels above 45 ug/dL.
So next time you eat asparagus, the smell of your normal body functions contains an important chemical group. I think even Ben Franklin thought something important was going on. I'm surprised he didn't add thiol discovery to his amazing list of achievements.