moleculeoftheday | July 3, 2007At the blog's previous location awhile back, I covered an oligoamine; spermine - which helps to compact DNA in cells. Spermine isn't volatile enough to smell much, but a shorter amine, putrescine, is.
Honestly I don't get the low MW amine thing. Pyridine smells pretty awful to me, but triethylamine and the like are just a bit ripe to me. Putrescine, apparently, occurs in decomposing flesh - it's the decarboxylation product of hte amino acid lysine.
Back Thursday.
moleculeoftheday | July 2, 2007There really isn't that much to this one, but I've always loved the name, and it's really easy to make: chalcone.
You can actually make chalcones with no solvent at all by just mixing aldehyde, ketone, and base in a mortar and pestle. Like Ritz mock apple pie, it's fun to try at least once, even if you don't have any use for it.
moleculeoftheday | June 28, 2007Working on a bunch of paperwork tonight so just a quickie - Ritalin.
Methylphenidate/Ritalin is probably the best-known ADD drug. It's just another phenethylamine - the broad class of drugs which includes pseudoephedrine, amphetamine, and MDMA. Another phenethylamine that is used in the treatment of ADD is simple amphetamine, which is sold as Adderall.
moleculeoftheday | June 27, 2007Cotinine is the principal metabolite of nicotine:
Cotinine spends quite awhile in the body; it can take several days to eliminate, so it's a marker for recent exposure to tobacco (secondhand smoke counts). This makes it one of the few drugs other than marijuana that will reliably show up on a drug test.
moleculeoftheday | June 26, 2007Bisphenol A is one ingredient that makes polycarbonate and epoxies work the way they do. A lot of people have fretted and expressed some concern about bisphenol A bioaccumulating - I can just about guarantee you're toting some around in your fat. More persistent and toxic to aquatic life is a derivative of bisphenol A - tetrabromobisphenol A.
Hanging a lot of halogens off of a compound is a pretty good way of making a flame retardant - we used to make amazing fire extinguishers with stuff called Halon (that link's highly recommended). I am told they were so good you could set up flame…
moleculeoftheday | June 25, 2007One aspect of opiates a lot of people don't know about is their effect on the GI. They slow gut motility, so opiate abusers often experience constipation (and diarrhea upon withdrawal). Opium used to be used medically as an antidiarrheal medication in a tincture with camphor - paregoric. Interestingly, opiates are still available OTC for the treatment of diarrhea.
Loperamide is unique among medically used opiates in that it isn't CNS-active - so you get the gut-slowing effects, without pain relief or addictive potential. It's the only opiate you can get OTC in most markets.
moleculeoftheday | June 22, 2007Henna tattoos are a pretty harmless way for hippies to entertain and adorn themselves. A relatively benign dye, Lawsone, stains the skin (or hair) a ruddy brown. Like a semi-temporary tattoo. However, you're limited to pretty much just that color. Some manufacturers have added p-phenylenediamine to their stuff, to create so-called "black henna."
p-phenylenediamine is a contact sensitizer (i.e., you can develop an allergy). This wouldn't be such a big deal if it weren't so ubiquitous - hair dyes, inks, and the like all have it too. Black's a tough effect to achieve.
Chemical sensitivity (the…
moleculeoftheday | June 21, 2007Sorry for the Internets silence - apparently cable modems can just up and die on you.
We have short memories. Ages ago, a molecule that was essentially a chimera of sugar and fatty acids was found to provide essentially no nutriment whatsoever (ironically, it was hoped it would be a rich source of calories). In fact, it passed right through you. It was essentially a noncaloric fat. Bafflingly, it took ages for people to realize that noncaloric fat could be a boon to the prepared foods industry. Ten short years ago, however, Olestra was loosed upon the world.
Olestra had a dark side, of course…
moleculeoftheday | June 15, 2007Internets troubles. Not sure when this will be fixed, but expect posts to be irregular to absent until at least early-mid next week...
moleculeoftheday | June 13, 2007Polyphosphoric acid is a mixture of phosphoric acids and its anhydrides:
I like it as an acid catalyst in organic synthesis - a lot of people hate it because it's so thick and hard to handle. The stuff is absolutely gooey mess; when you heat it up, it gets down to about the consistency of honey. The neat thing is that lots of stuff will go into it (it is a strong acid goo, after all), but once you quench your reaction with water, your stuff will often crash out.
During a blissful few months, I cranked out a series of Fischer indoles with the stuff. Everything seemed to work!
moleculeoftheday | June 12, 2007Friday's entry on safrole inspired a number of comments on what sort of animal it looked like. One person mentioned a chestnut from a few years back: NanoPutians!
NanoPutians are molecules that look kind of like people. James M. Tour at Rice has a grant to use the little nanopeople in chemical education programs, which I think is actually a really neat idea. The jokes, however, are too easy to pass up.
The above is "NanoKid," which, perversely, is the lone progenitor of a whole army of NanoPutians. The others are generated by microwaving NanoKid with decapitated NanoPutian heads.
I have…
moleculeoftheday | June 8, 2007Safrole is a simple organic compound found in sassafras oil:
It has a pleasant odor and used to be used to flavor root beer, but sassafras oil has fallen out of favor in the past few years for a few reasons: first, safrole has been deemed carcinogenic and banned as a flavoring agent by the US FDA. Second, it's actually a drug precursor - like pseudoephedrine-containing allergy medicines, it's not illegal to buy sassafras oil (as far as I know, I've never tried!), but it's watched closely by US drug enforcement. The people buying pints at a time probably aren't making a few gallons of root…
moleculeoftheday | June 7, 2007Dimethyl sulfide is another one of those small, volatile sulfur compounds:
Predictably, it lands on the malodorous side of the fence, but at low concentration, it purportedly smells pleasant. As Derek Lowe notes, it is the "smell of success" when the Swern Oxidation succeeds.
moleculeoftheday | June 6, 2007Periodically, we get these "Ask a Scienceblogger" questions via email asking for someone to volunteer to answer. Usually I don't feel like I have anything to add, but this one was frivolous enough for me to know something about it... Sorry for the not-a-molecule post, back with the regular content tomorrow.
A square piece of dry paper can not be folded in half more than 7 times. Why?
Actually, it's a myth:
Once, in undergrad, an acquaintance offered up a bet for $100 to anyone who could fold a piece of paper nine times (or some other number greater than conventional myth - eight, maybe).…
moleculeoftheday | June 5, 2007Trehalose is a simple head-to-head dimer of glucose:
Like a lot of sugars, it holds onto water like crazy; some plants use it as a protectant in dry conditions.
Molecular biologists also use it in PCR; apparently, it stabilizes the enzyme, while destabilizing the dsDNA produced by the reaction.
moleculeoftheday | June 1, 2007The phosphoramidite method of oligonucleotide synthesis has been invaluable. WIth a few reagents and an expensive machine, you can make any sequence of DNA or RNA. Purification can be a bit tricky, and it only gets worse as you get longer (once you're up to about 100 bases, you probably have a third or less of your desired stuff, the rest is shorter, truncated strands). That said, it's pretty amazing - making a strand of DNA or RNA is as simple as spelling it out.
Oligos are important! The polymerase chain reaction needs two of them. Companies have been set up exclusively to sell them. Can…
moleculeoftheday | May 30, 2007Acetaminophen/paracetamol is a great drug. It comes without a lot of the GI irritation problems of aspirin and other typical COX inhibitors. Unlike aspirin, it doesn't increase clotting time. No nagging feeling you're going to give your kid Reye's syndrome. However, it has an unusually low threshold for overdose, due to a quirk in its metabolism.
Most acetaminophen is conjugated to a sugar derivative and excreted. A small fraction, however, gets converted to a toxic metabolite: NAPQI.
NAPQI is a potent hepatotoxin - much at all and your liver is shot. As I intimated yesterday, glutathione…
moleculeoftheday | May 29, 2007The atmosphere doesn't just keep you alive and protect you from the sun - it is responsible for the face of life as we know it. One-fifth of the atmosphere is oxygen, happily waiting to accept electrons from whatever's available. Oxidative metabolism turns sugars and the like into CO2, just like fire. This provides loads of energy, of course. This wasn't always the case!
Long ago, there was virtually no O2. During the course of evolution, some humble microbes began to produce oxygen. This wasn't by design, mind you - the oxygen was waste! Photosynthetic bacteria, like plants, gave off oxygen…
moleculeoftheday | May 25, 2007From medicated powder to cigarettes, it's no secret that small molecule ligands can induce a cold sensation. Usually, this means menthol. However, like any protein ligand, non-natural small molecules can stand in.
Icilin has an enhanced affinity for receptors to which menthol binds:
Icilin induces sensations of intense cold when applied orally in humans, and induces 'wet dog shakes', a behavioral marker of cold sensation, when given to rats.
Icilin: 2.5X more effective than the leading thermosensory agonist at causing wet dog shakes!
moleculeoftheday | May 23, 2007You can't measure something unless you can see it. Scientists have loads of instruments to detect things by all kinds of methods, but the most popular and simplest has to be UV-vis spectroscopy. Shine some light over your stuff, see how much gets through, you know something about what's there. UV light is particularly popular - anyone who's ever done DNA work has used 260nm light for this purpose.
One problem, though, is that just about everything absorbs some UV light - 260nm is pretty well-behaved, but not without its difficulties. Colored things, however, are a bit rarer. If you can…