Confusing 'Chemistry' Image of the Day

This image appeared in an NPR Shots blog post outlining the CDC's recent recommendations on male circumcision:

Source: NPR News / Corbis Images

Please help me understand - What on earth do the floating molecules have to do with this story? 

I grok that the image suggests two men deep in conversation. The article doesn't mention any drugs. Nor bodily substances. No pheremones, hormones, biomarkers, or viral particles enter the conversation. Just another case of stock images gone wrong?

'Green' Coca-Cola

Credit: Soda stream USA

I really enjoyed hearing Bob Mondello's NPR blurb about the debut of "Coke Life" in Argentina. Apparently, this soda contains stevia and table sugar, and sells in a plant plastic derived bottle. It's not as calorie-laden as traditional Coke, and bills itself as "green" (renewable). Thus, the new logo Coca-Cola rolled out: a green background, in place of the traditional red known the world over.

I have a secret: I've often wanted to peer behind the scenes as a Coca-Cola chemist. Think about all the different stuff you'd get to play with! Considering sweeteners alone, you have Diet Coke, Coca-Cola, Coke Zero, and now "Coke Life," which use aspartame, high-fructose corn syrup, sucralose, and stevia, respectively. Not just those, but dyes, vitamins, stabilizers, emulsifiers, preservatives, and much, much more. Best part? If you invent something exciting, you get to see it used by billions of people - more than your average pharmaceutical (and a much shorter development cycle!).

It's interesting to speculate on why certain artificial sweeteners didn't make the Coke cut. Certainly, lead acetate didn't - ask the ancient Romans why not. But diner table stand-by saccharin didn't, either. Perhaps too much bad press on its tenuous ties to cancer? And why not go back to using a truly "natural" sweetener, like sugar or honey? Cost plays a role here, as does consumer preference.*

I look forward to trying "Coke Life" myself. If anyone from Argentina reads this, let's work out some shipping arrangements.

*To me, HFCS tastes overwhelmingly cloying, but I've heard dedicated Coke drinkers describe saccharin as "metallic," aspartame as "sharp" or "bitter," and stevia as "too sweet" (Ha!). 

Friday Fun: Artemisinin on NPR

NPR Story

2012 Keasling lab article in PNAS

Wikipedia: Artemisinin

More Car Talk "Chemistry"

Regular readers know my fascination for all things NPR, and Car Talk in particular. This week's broadcast had me rolling in the aisles for a different reason: some cover-your-eyes-awful chemistry.

A "white residue" in the engine?
Get the peanut butter!

Let's set the scene: Tom and Ray had taken a call from Ann, who begged that they were her "last hope" for an aging, ailing Subaru wagon. Ann's son apparently noted a funny white "mist" coming out of the car a few months ago. After several expensive repairs (heater core, radiator), a white, powdery substance was still forming in the engine block.

The guys considered that a single engine part had failed, perhaps something plastic or rubber, but discarded that theory since previous repairs had not fixed the problem. Then Tom suggested that the car might be continuously producing the white residue, perhaps through combustion gases which found their way into the radiator fluid through a leaky gasket.

Tom short-listed some potential combustion "bad actors" - carbon, carbon dioxide, carbon monoxide, nitrous oxide. Aha! The nitrous oxide must be forming nitric acid, thus corroding the engine block. "It's Chemistry 101!" he exclaimed.

Except...not. I know that nitrogen dioxide or NO_x emissions from cars generate nitric acid in the presence of water, but last I checked, whipped cream cans and dental offices everywhere remained safe from acidic corrosion.

Undaunted, through admitting "I have no idea, I'm just making it up," Tom pressed on: perhaps a salt, such as copper nitrate (a blue solid) or, even better, copper carbonate ("It just sounds more white, like sodium bicarbonate") gummed up the works. Maybe, since the heater core was made from aluminum, that was the culprit?

Tom: "What about aluminum carbonate, A-L two C-O three!"
...or, maybe Al₂(CO₃)₃?

Finally, Ray chimed in: "MIT's on Line 1, they want their diploma back."

Happy Saturday,
SAO

Note: I paraphrased this conversation as best I could, since the recording hasn't yet appeared online. When it does, you can hear the full 3/30/13 episode at cartalk.com.

A Very Important Point

Driving home tonight, I happened upon a fascinating story on All Things Considered. This latest installment of Julie Rovner's series on women's reproductive health analyzes the debate between supporters and opponents of Plan B (levonorgestrel) and ella (ulipristal), two controversial emergency contraceptive measures. I'm hardly well-versed enough to take sides, but something said by one of the scientists Ms. Rovner interviewed really resonated with me (at 4:32):

"Chemically related is not chemically identical." - Dr. Diana Blithe, Contraceptive Program Director, NICHD

Well, in a word: yes! As a career medicinal chemist, I completely concur that tiny changes - say, a methyl here or a deuterium there - can have huge effects on drug potency, targeting, clearance, recognition, plasma concentration, etc, etc.

Dr. Blithe's statement rebuffed a remark made by another researcher, who said that since abortifacient RU-486 (mifepristone) and ella contained similar core skeletal structures ("chemical cousins"), they must function similarly at the same dose.

Actually, are those two drugs really that similar?

Here's ella and RU-486 side-by-side. You'll notice that the "Western" fragment (left) is identical. This probably underlies the two drugs' similar mechanisms of action (progesterone receptor competitive inhibitor) and similar active metabolites (amine demethylation).

But what about at C-17? For one, they're locally diastereomeric - the alcohol points "up" (beta) for RU-486, but the related acetate "down" (alpha) for ella. The various moieties dangling off the right side subtly change drug targeting, explains Dr. Blithe, directing effects toward the ovary (ella) or the uterine lining (RU-486). Finally, different uses (delayed ovulation vs. pregnancy termination) combined with different pharmacokinetics result in different dosing: ella sells in 30 mg tablets, while RU-486 utilizes 200 mg of active ingredient...quite a large dose for a steroid.

"And Let the Power of Chemistry Do the Work"

I love to listen to NPR on Sunday mornings. They usually recap all the great shows, from Wait, Wait, Don't Tell Me! to Says You. But, I reserve a special place in my heart for Car Talk, the hilarious auto advice show produced by two Boston natives, who dub themselves "Click and Clack."

If this were my car, I wouldn't pour acid on it!
1957 Ford Thunderbird

This morning, a caller wanted advice on a "body problem" with his car. He claimed to have driven by a construction site, and had had concrete inadvertently splashed on the door and window of the passenger's side. The show hosts cracked a few jokes, then mentioned that he could probably scrape the concrete off the window simply using a straight-edge razor blade.


But the door frame was another matter - how do you remove concrete from a painted plastic panel? One of the hosts suggested a simple rubber mallet, but the other mentioned muriatic acid (HCl, or hydrochloric acid). He posited that the acid would seep in and dissolve the concrete, while leaving the underlying paint relatively untouched. The title of this post (see above) summed up his final comments to the caller.


Of course, you might not want to pour HCl over your hood, or the undercarriage...I'm sure mufflers, battery terminals, and engine blocks don't hold up too well to this home remedy!

Did Someone Say Pink Slime?

Face it: School lunches have always looked a bit dodgy. Thick, overcooked casseroles. Spongy grey sandwich patties. Slabs of greasy pizza. Thus, when industrial beef producers suggested one more (cheap) processed ingredient, cash-strapped school districts gladly agreed.

Source: theblaze.com

So began the "Pink Slime" fiasco (picked up by the msnbc* Vitals blog, NPR's The Salt, and, of course, our friends at change.org). What is it? If you come from the ranch side of the equation, you refer to pink slime as lean, finely-textured beef (LFTB). Connective tissue and scraps from industrial butcher plants are mixed with ammonia gas or ammonium hydroxide, which degrades the protein matrix of collagen and elastin into component amino acids, and sterilizes the resulting goopy mass against microbes like E. coli. The final product can be blended into hamburger and other "finished" meat products.


So, what are the arguments against this bio-sludge (besides appearance)? First, consider nutrition: there's less in pink slime than in other meat products. There's a higher fraction of insoluble protein, which may be hard to digest, but on the plus side, there's less fat in LFTB than in standard ground chuck. Despite its off-putting look, the final material may actually have a composition closer to soy protein than beef.

pH meter
Source: General Tools

Second, how much ammonia is required? Levels high enough to raise the goop's pH to ~9 seem to kill all pathogens, but batches tested by the NYT back in 2009 showed pH levels as low as 7.75. So what? Well, since pH tracks logarithmically, that corresponds to 18x less total base, which might reduce any ammonia odors but correlates to increased bacterial contamination. 


Finally, it's all about the labeling. A generation of parents accustomed to fighting high-fructose corn syrup (oops, "corn sugar"), artificial dyes, and allergens in processed foods would prefer including ammonia in the final ingredient list. However, manufacturers - and the USDA - consider this a production step, not a discrete additive like ammonium phosphate (leavening agent) or ammonium chloride (licorice, baked goods). 

Mmm...beef.
Source: picturedepot.com

Time will tell if the public uprising surrounding pink slime will lead to cancellation of school lunch contracts. But processed meat products aren't going away anytime soon: consider chicken nuggets, hot dogs, sausages, or scrapple (if you're into that). Or the ubiquitous gelatin, made from bones and cartilage, which gives the gummy to bears and puts the gel in Jell-O. 


*Chemophobia update - Ye Gods, msnbc. Way to scare everyone. How about a scientific fact check? Ammonia is not a "pink chemical" - it's colorless, and you don't use it to leaven cakes (see ammonium phosphate, above). Backtracking to the original report, we see mention of flammability and building bombs . . .really? Ammonia is much more commonly used to clean floors and windows.

Cool Science - N.dG.T.

Meet Neil deGrasse Tyson.

He's the director of the Hayden Planetarium. He's appeared on The Colbert Report, The Daily Show, and Late Night with Conan O'Brien. He answers astronomy questions posed to him by random netizens on reddit, and gives dozens of public talks to school kids.

Noted science writer Carl Zimmer has recently written a fairly glowing profile of him, that appeared in a well-read magazine.

He hosts episodes of NOVA for PBS, and Fox will re-boot Cosmos with him in front.

But it was his AP stock photo (see right) from this NPR book review that drew my eye - when's the last time being a scientist looked so cool?

Links and Such

A few recent internet chemistry items for your viewing enjoyment:

Paul is already hard at work predicting October's Nobel Prize in Chemistry.

Chemjobber waxes on vacation requirements (or not) in academic labs.



Hey look, nitrogen particles!  Wait, no, that's snow...

Over at Forbes, Matt has a profile of Peter Hirth, the man behind Sutent and Zelboraf.


Ivan Amato chats up horseradish and pain receptors in the Washington Post.

NPR's Morning Edition covered a recent Nature article, but what the heck is a "nitrogen particle"?