moleculeoftheday

General anaesthesia has come so far, and yet not. Back in the day, we used to use lipophilic compounds like diethyl ether and alkyl halides like chloroform, and now we use...well, lipophilic alkyl halides like desflurane. Fortunately, desflurane doesn't cause so many toxic effects, due largely to…

I don't think I'll ever be able to pick out which mushrooms aren't poisonous. Poisons vary pretty widely across species; a lot of them are small peptide type molecules. One of the few simple small molecule mushroom poisons is orellanine: It bears a striking similarity to the bipyridyl ligand…

Salts are mixtures of charged species, or ions. They have an avid tendency to remain solid due to the strong interactions between their charged components. About a hundred years ago, people started noticing certain compounds that were ionic would nonetheless melt below or around room temperature.…

Despite the name, penicillamine isn't an antibiotic; it's actually a metabolite of penicillin-class drugs. It is given as the pure chemical too. It is an immunosuppressant, among other things. My favorite medical use of it is its role in chelating copper as a treatment for Wilson's disease, a rare…

Albendazole is a member of the benzimidazoles - the 6+5 membered ring system at the heart of the molecule. The benzimidazole class of drugs is used to treat many parasitic worm infections. They work by impairing microtubule function. The benzimidazoles are gratifyingly simple-looking drugs.…

Last week it was revealed that for just about the entire 1970's, former SCOTUS chief justice Rehnquist was taking Placidyl. This is too long by any measure - it's been unavailable in the States for almost a decade (due to better alternative supplanting it), and even when it was available, it was…

Chemotherapy, in the cancer-treatment sense, isn't very selective. Fortunately, cancer cells divide so much faster than regular cells, this imparts a measure of selectivity. All chemotherapeutic agents are poisons of one sort or another, but we continue to get better. Mechlorethamine is just an "…

One of my best friends in undergrad, upon learning about the use of acetal protecting groups for carbonyls, exclaimed, "they're like ketone condoms!" Indeed. Protecting groups are ubiquitous in organic synthesis, and another one you see all the time is Boc, which is used to protect amines: Boc2O,…

My dentist has an incredible knack for administering anesthetic without much pain. I'm not sure what combination of factors are at play, but getting work done there is essentially painless. My main problem for years was the fact that my mouth was numb for a good part of a day after leaving. I went…

Azelaic acid is a pretty simple small molecule: It is used topically in dermatology.

I picked this molecule for one main reason: I was flipping through a physiology book and read this statistic: your body goes through on the order of one liter of bile per day! Did you have any idea? That is up there on my goofy big numbers in your body list, the champion of which is still this:…

Oxalic acid is a bifunctional carboxylic acid. Your body will make it as the result of metabolism of ethylene glycol if you ever drink antifreeze, resulting in the catastrophic precipitation of calcium oxalate in your kidneys. Some foods have (fairly low) levels of oxalate. A small portion of…

There are a number of "strong" acids that are essentially completely dissociated in water - hydrochloric and sulfuric acid are two of the most common. Unfortunately, these are often volatile (as in HCl), insoluble, or otherwise ill-behaved in organic solvents. The organic sulfonic acids are quite…

The fluoride ion is important to synthetic chemistry, often because it can be used to cleave silyl ethers (the silicon analogue of a carbon ether). Fluoride is notorious for holding onto water (like any tiny ion - lithium is about as bad), so even an "anhydrous" solution of TBAF in (say) THF will…

Makes MoTD a bad blogger. Back Monday.

You may have heard of a guy named Kurt Vonnegut. What you might not know is that his lesser-known little brother Bernie was the guy who came up with the idea of using AgI for cloud seeding. From little bro Kurt's Timequake: Question: What is the white stuff in bird poop? Answer: That is bird poop,…

Tris is one of the most common buffers out there and absolutely ubiquitous in molecular biology. The idea behind a buffer is that you have a compound that takes on a proton (hydrogen) at a certain pH, usually somewhere near neutrality, you have about half with and half without a proton, and you…

Methyl viologen is a groove-binding DNA ligand; that is, unlike an intercalator, which slips between bases, it slips into the grooves of the DNA helix. You've probably heard of it as paraquat. It is an herbicide, but it's not that specific; the stuff can hurt you, too. The mechanism of action here…

The catnip plant belongs to the genus Nepeta. The molecule responsible for its odd effects on cats is called nepetalactone: Apparently catnip can repel insects in a garden, and some people have looked into whether nepetalactone works as an insect repellent.

Sorry, this week evaporated. Back to regular posting Monday.

As many estimable colleagues have noted, guanine's weird. It's not that soluble, which isn't too much of a problem when it's a part of your very soluble DNA, but from an origin-of-life perspective, that's a hassle. Envisioning a primordial-soup scenario with guanine is tricky, because of this low…

Pfizer's Lipitor is the highest-grossing drug out there right now. This single molecule sells over $10B/year. As discussed in the allopurinol entry, this is another example of a small molecule enzyme inhibitor. The class to which it belongs, the statins, works on one key step of the steroid…

Polonium-210 is a radioisotope that's gotten lots and lots of press in the last few weeks because of its purported role in the death of Alexander Litvinenko. Polonium is an alpha emitter - that is, in the process of decay, it gives off energetic helium nuclei. They're massive, so they are stopped…

Cyclopropane is another markedly strained ring (the smallest simple ring geometrically possible, really): It used to find some use as an anaesthetic. Strained rings being strained rings, however, it had a nasty habit of exploding. One movie made good use of this phenomenon (without commenting on…

Squaric acid is an unusually strong acid for an organic acid: It's also unique because of its strained ring. In general, five- and six-membered rings dominate in chemistry - hence the endless parade of hexagons. Higher rings are tolerated but not-so-favored. Lower rings are possible, but, again,…

As a followup to the entry earlier today, here is a drug that is used in the treatment of gout: allopurinol. In vivo, purines are metabolized by the enzyme xanthine oxidase to hypoxanthine and xanthine, which are converted to uric acid: Allopurinol is a hypoxanthine mimic, which is oxidized by…

Happy Thanksgiving week to the American readers! In celebration, let's talk gout! Uric acid is the final product of purine (the bases that comprise exactly half of your DNA) catabolism in humans. Normally, you urinate it out with no problems. Below are guanine and adenine (the two purines that are…

With a MotD Thanksgiving-themed double-header, which will probably be the last posts for the rest of the holiday week over here.

Inhalants are ubiquitous illegal drugs of abuse and a public health problem worldwide. Most lipophilic solvents have some kind of neurotoxicity (some gas anaesthetics, in fact, work based mainly on their lipophilicity, and are only special because of lower toxicity). Unavoidably, we find these in…

Brazilian reader Luis Brudna has begun translating some MotD entries into Portuguese. Feel free to have a look if you're not reading this in your first language!