Main Chemical Feed

Confusing Toxibbreviations

Sun, 27 May 2012 14:53 GMT

Dr. Freddy, over at Synthetic Remarks, presented an interesting problem: why do so many molecules have such confusing abbreviations? If you think of an abbreviation as a linguistic shortcut, a way to save time while communicating complex ideas, it makes sense to use something everyone can understand. Unfortunately, the simplest workarounds can also be the most confusing; when I write "RM," do I mean 'recovered material,' or just an alkyl group attached to a catalyst? Depends on your audience.

The strangest shorthands? Natural product toxins.

Batrachotoxin: "Nothing like Brevetoxin."

For convenience, when chemists isolate a new biocide, they assign it a name ending in "toxin," which inevitably shortens to "TX." Pop another letter on the front to differentiate, et voila! (This probably made sense back when we'd found just a small handful of these compounds, but they're getting crowded now.)

Here's a few I tracked down, listed alphabetically:

ATX: Antillatoxin, Anenome toxin, Ammodytoxin, Altertoxin, Aflatoxin, Anatoxin, Adriatoxin
BTX: Botulinum toxin, Batrachotoxin, Brevetoxin
CTX: Charybdotoxin, Conotoxin, Cholera toxin, Ciguatoxin
DTX: Dendrotoxin, Dinophysistoxin, Diphtheria toxin
ETX: Epsilon toxin, Erabutoxin, Edema toxin, exotoxin
FTX: Funnel Web Spider Toxin

Nereistoxin: "Don't call me Noxiustoxin!"

GTX: Gonyautoxin, Geographutoxin, Gambierotoxin, Gila toxin
HTX: Histrionicotoxin, Hemitoxin, Horridum toxin, Homoanatoxin
ITX: Iota toxin, Paralytic insecticidal toxin, immunotoxin
JTX: Joro spider toxin
KTX: Kaliotoxin
LTX: Latrotoxin, Leukotoxin, Anthrax Lethal toxin
MTX: Maurotoxin, Maitotoxin, Maculotoxin, Mosquitocidal toxin
NTX: Nereistoxin, Noxiustoxin, neurotoxin
OTX: Ostreotoxin, Orphan toxin
PTX: Pertussis toxin, Palytoxin, Pectenotoxin, Pumiliotoxin
QTX: Quinquestriatus toxin
RTX: Repeat toxins

Saxitoxin: "Will the real STX please stand up?"

STX: Shiga toxin, Saxitoxin
TTX: Tetrodotoxin, Tetanus toxin
UTX: Uraemic toxins
VTX: Verotoxin, Verrucotoxin
WTX: Weak toxin (cobra), Waglerin
XTX: None found...open for business!
YTX: Yessotoxin
ZTX: Zetekitoxin, Zeta toxin

Readers - Have I left out your favorite poison or abbreviation? Let me know in the comments!

Metal-Organic Frameworks

Sat, 26 May 2012 21:00 GMT

Book reporting on applications of MOFs and discussing both the advantages and limits of the material is reviews by Jiří Čejka, Czech Republic

Meth mouth: not 'toxins', just good ol' tooth decay

Sat, 26 May 2012 15:59 GMT

As a long-time fan of media critic Jack Shafer, I remember well his diatribes against the myth that 'meth mouth' (the tooth decay that afflicts long-time methamphetamine abusers) is caused by the chemistry of methamphetamine or any contaminants from the preparation. The causes (dry mouth and lack of dental care) has been discussed in the peer-reviewed literature.

So I was surprised to see it in the middle of a really interesting article on underground chemistry by Discover Magazine:

In attempting to synthesize crystal meth, these do-it-yourselfers have caused a rash of trailer park explosions and often unwittingly produce a drug coated with toxins like hydroiodic acid. The best way to remove those noxious byproducts is by washing the drug in alcohol using a Büchner funnel, a specialized lab vacuum. But most kitchen chemists have never even heard of it. When this final purification step is skipped, the toxins eat away at the user’s gums, teeth, and inner lining of the cheeks, resulting in a toothless, hollowed-out condition known as “meth mouth.”

No, no, no. What causes 'meth mouth'? Is it toxins? Is it uneluted hydroiodic acid? Well, let's look at the American Dental Association page that it links:

The extensive tooth decay is probably caused by a combination of drug-induced psychological and physiological changes resulting in dry mouth and long periods of poor oral hygiene. A methamphetamine “high” lasts much longer than that produced by crack cocaine (12 hours versus one hour for cocaine). This can lead to long periods of poor oral hygiene. And while they are high, users often crave high-calorie, carbonated, sugary beverages or they may grind or clench their teeth, all of which can harm teeth.

So, there we have it. There's no reason to blame hydroiodic acid (or the solvents, or "toxins" or acids in the process) when it comes to 'meth mouth'; it's just advanced tooth decay.

Don't keep on trackin'

Sat, 26 May 2012 03:47 GMT

THE brief of America's Federal Trade Commission (FTC) does not typically extend to its wards' corporate communications. That did not stop Ed Felten, the FTC's technology chief, from breaking the news that Twitter was jumping on the "Do Not Track" (DNT) bandwagon, a move the firm later confirmed—in a tweet, naturally. The microblogging giant is the latest to let a user specify in a web browser that he does not wish his behaviour to be followed and used for targeted advertising or assembling personal profiles.

The FTC has its nose in DNT because the directive needs regulatory enforcement and civil liability to be workable. Chris Soghoian, a former FTC staffer who helped come up with DNT and shepherd it at times, explains that advertisers' explicit agreement to respect users' wishes means that the FTC can pursue those who nonetheless disregard them for "deceptive practices", which falls under the agency's purview. Individuals, meanwhile, have a contractual basis on which to sue companies which renege on their word.

Technically, DNT is a bit of text which reads "DNT: 1" (where "1" stands for "on" and "0" would mean "off"). This is sent as web metadata, part of the hidden messages that a web browser and web server exchange when negotiating to receive a page or media file. When a switch in an internet browser's options is flipped to "do not track", companies like Twitter that have signed up to the pledge will no longer record information about a visitor's behaviour when the user employs that browser.

The DNT switch has already been included in Mozilla's Firefox and Microsoft's Internet Explorer, while Apple hides the option in its Safari browser among software developer features. Google's Chrome has a downloadable plug-in to enable DNT that will be built into future versions of the software. Another popular browser, Opera, has the option in its current beta version. These five companies' desktop browsers account for nearly all computer surfing (mobile browsers lag in this regard). An independent site run by privacy and security researchers, called donottrack.us, explains how to flip the switch in each of them. In Firefox, for instance, the setting is labeled "Tell websites I do not want to be tracked" and the default option is off. Mozilla says 9% of desktop Firefox users and 19% of its mobile surfers have checked the box (while noting that it "does not collect or store personal information about our users to determine these statistics").

But it is one thing to bung the switch into browser, and quite another to get advertisers to comply with the settings, as can be seen in the case of Apple's Safari browser and its less-restrictive default setting that blocks third-party tracking using web cookies. This is not the same as DNT, but it prevents many forms of snooping on customers' online habits. Yet it did not stop Google, which lives off targeted advertising and has committed to DNT in its broadest form, from bypassing this setting with an elaborate hack. The search firm has fessed up to doing this though it says its intent was benign. The FTC is investigating the company for violating a 20-year consent agreement signed in 2011 over privacy violations surrounding its launch of Google Buzz that requires Google to be extra vigilant. This sort of behaviour puts a question mark over its commitment to DNT.

The World Wide Web Consortium (W3C), a group that has long championed internet standards, thinks that a simple on/off switch introduces a new problem, which concerns the default setting. If this is to be "off", ad networks say they will collapse; if it is "on", privacy experts argue that users are being opted in. The imbroglio involving Apple and Google illustrates another worry. Apple chose "off" for third-party tracking in Safari, so it might be argued that Safari users never made that choice themselves and thus Google did not violate their privacy; Apple cannot, after all, presume its actions reflect all its users' intentions.

W3C wants the Tracking Preference Expression standard under development to distinguish between users who explicitly do not wish to be tracked, those who do and, on top of that, those who have not expressed a preference. That might result in a DNT checkbox which lets a user select "yes" or "no". If unticked, the browser sends no DNT metadata at all.

Ad networks belonging to the Digital Advertising Alliance, representing 90% of online ads in America (including Google and its DoubleClick division) have agreed in principle to DNT and related proposals. These are voluntary but, as explicit privacy policies, contractually binding. But grumbling persists over the details, with networks trying to carve out exceptions that allow them to track certain kinds of actions and not others. Oddly, the networks also want to be able to gather information about users, but not use it for tracking.

But the FTC seems firmly resolved, and privacy advocates are pushing hard for a tight definition of what "not tracking" means. Mr Soghoian notes that DNT went from being called ridiculous and naive to impossible to par for the course in three years. He believes that even without advertising and tracking networks' full acquiescence, the FTC would have the teeth to pursue enforcement. "Do not track" also enjoys strong backing from Neelie Kroes, the European Union's digital tsarina, who in June 2011 demanded that advertisers self-regulate to allow European web users to opt out of tracking within a year. One way or another, then, tracking is set to become much more difficult. Internet giants are no doubt peeved—and preparing to tweak their business models.

Angewandte Chemie 22/2012 – The Spice of Life

Fri, 25 May 2012 21:00 GMT

An overview of the latest issue of Angewandte Chemie

Friday chemical safety round-up

Fri, 25 May 2012 12:28 GMT

Chemical health and safety news from the past week:

Celebrate lab personal protective equipment on June 4! “If you wear your PPE and you consider it a smart, effective way to stay safe in the lab, would you send me a picture?” Chemjobber asks. Send photos to LabPPEDay@gmail.com and they'll appear on Tumblr on the 4th. Anonymous contributions are welcome.
For all the contributions for this week's #ToxicCarnival (aka chemistry bloggers' favorite toxic chemicals), go visit Sciencegeist: Monday, Tuesday, Wednesday, Thursday, Friday
Via @Canageek, an Organic Synthesis prep for hydrogen cyanide with this safety note: “Gattermann recommends that the operator smoke during the preparation, for he found that a trace of hydrogen cyanide is sufficient to give the tobacco smoke a highly characteristic flavor. This preliminary warning is useful in case of leaky apparatus or a faulty hood.”
John at It's the Rheo Thing discusses a monomer he won't work with: Urishiols
Dow is expanding its pilot program on university lab safety to Penn State
Mere weeks after issuing its report on a fatal explosion from spark-producing “hot work” at a DuPont facility in New York, they're now heading to Arkansas to investigate another hot work incident at a Long Brothers Oil Company tank site
Ohio legislation will give doctors information on the chemicals used by oil and gas drillers, but will prevent them from sharing that information with the public–including public health and regulatory agencies

Fires and explosions:

A fire involving (possibly empty) acetylene tanks at an Air Liquide plant in Louisiana may have started with a faulty valve
A reactor overpressurized and exploded, blowing a hole in the roof at MFG Chemical in Georgia; the facility was making Coagulant 129, which is used for water treatment
Queen's University Belfast, in Ireland, had a chemical storeroom fire, no word yet on the cause

Leaks, spills, and other exposures:

A chlorine release at a Georgia Gulf chemical and vinyls plant in Louisiana sent four workers to hospital
Fumaric acid spilled at a Con-way Freight building in Massachusetts
An employee at Schott North America in Massachusetts mistakenly mixed three gal of sodium hypochlorite with 100 gal of hydrochloric acid, producing chlorine gas
Also in Massachusetts, a forklift punctured a 250-gal container of 50% sulfuric acid at Pan-Glo New England
Workers at Macklanburg-Duncan in Oklahoma were mixing a sodium hydroxide solution about 3 p.m. when the solution started smoking and three workers became nauseous, supposedly because whatever chemicals were involved were mislabeled (NaOH and water? or were they mixing the NaOH with something else?). The company “manufactures building products such as weather stripping, flooring and decorative moldings.”
A Princeton University postdoc was treated for chemical burns to her face when a (waste?) bottle containing nitric acid and an organic solvent blew up. It was in a cabinet, but the force of the explosion forced open the door. (Yet another example of why you should always wear PPE in lab, even if you personally are not doing anything dangerous.)

Not covered: meth labs; ammonia leaks; incidents involving floor sealants, cleaning solutions, or pool chemicals; transportation spills; and fires from oil, natural gas, or other fuels.

1 Million Served

Fri, 25 May 2012 12:11 GMT

Earlier in the week Chemistry Blog crossed the 1 million visitor mark. I just want to say thank you to all the readers and fellow writers that have helped to make this happen. It has been a good 6 years.

Best,
Mitch

Cosmic revelations

Fri, 25 May 2012 11:44 GMT

THIS has been a busy week for space buffs. First, SpaceX, a company founded by Elon Musk, co-founder of PayPal, an internet-payments firm, successfully launched its Dragon space capsule into orbit on May 22nd. Now, three days later, the Dragon made history by becoming the first private craft to dock with the International Space Station (ISS), after it was clasped by a robotic arm (see picture) and brought to a berthing port. All that remains is to unpack the half a tonne's worth of payload, including food and other supplies, it has ferried to the orbital station on behalf of NASA, America's space agency. In between Mr Musk's feats, Jeff Bezos, the internet tycoon behind Amazon, an online retailer, put the result of his space venture's engineering efforts, the prototype Charon craft, on display at Seattle's Museum of Flight.

Most momentous of all, though, could be a decision announced in Amsterdam just hours before Don Pettit, an American astronaut aboard the ISS, "got us a Dragon by its tail", as he put it. The board of the Square Kilometre Array (SKA) consortium decided whether to build a new radio telescope in South Africa, whose bid was recommended by a panel set up to look into the matter, or Australia. In the event, the consortium decided to split the site between Boolardy Station in Western Australia and the Karoo in South Africa's Northern Cape.

Both sites are well-suited to radio telescopy. They are out of the way and experience little man-made radio interference from mobile-phone networks, television and radio broadcasts. The politic solution has been welcomed, officially at least, by the competing nations, though South Africa's ministry of science and technology sounded a slightly disappointed note in a statement. However, Bernie Fanaroff, who spearheaded the African bid, was ebullient about the prospect of his country hosting what is, physically speaking, the world's biggest scientific experiment (and, no doubt, the contracts that come with it).

The SKA may be less sexy than the Dragon and the ISS. It is certainly cheaper; its estimated €1.5 billion-2 billion ($1.9 billion-2.5 billion) price tag may be hefty as scientific projects go, but it pales in comparison with the $100 billion already poured into the ISS. Yet unlike the orbital station the radio telescope, 50-100 times more powerful than any predecessor, promises to do plenty of useful science, by exploring the formation of the first stars and galaxies, the role of magnetism in the early cosmos, the nature of dark matter, dark energy and gravity, and whether intelligent life has ever existed anywhere besides Earth.

The sheer scale of the endeavour is mind-boggling. A typical optical telescope might have a diameter a few million times the wavelength of the light it is collecting. Applying that scale to radio astronomy—where wavelengths are measured in centimetres—would require dishes several kilometres across. Building a single dish of that size would be impractical, so the SKA is planning to use around 50,000 smaller receivers stitched together in a vast web.

Many of the receivers were to be concentrated in a core about 5km on a side, with the rest arranged into a set of elegant spiral arms 1,500km long. A signal processing technique known as interferometry would then allow the cluster to function as one virtual instrument, with a receiving area equal to the combined area of the individual dishes (yes, one square kilometre) and a baseline (a measure of the telescope’s resolving power) equal to the distance between the furthest individual components—or about 3,000km.

How exactly the SKA will work across two continents is something the consortium has yet to figure out. The idea is for each of the sites to focus on a different part of the radio spectrum—Australia for the lower end and South Africa for the rest. Tim O' Brien, from Britain's Jodrell Bank Observatory, which was chosen last year as the SKA's headquarters, told the BBC the split did not pose a huge challenge.

Yet splitting the project is bound to increase its already considerable technical complexity. And it will almost certainly raise the ultimate price, possibly closer to the $6 billion America's National Science Foundation reckoned it would cost when the United States decided not to join in. That said, it would still be a bargain compared to the ISS—and, if it were to deliver on all its scientific promise, possibly a small price to pay for unravelling more of the mysteries of the universe.

Amusing News Aliquots

Fri, 25 May 2012 11:09 GMT

Silly samplings of this week's science news, compiled by Bethany Halford and Lauren Wolf.

Credit: Flickr user buildinghugger

MIT engineers devise coating to squeeze the last drops of delicious ketchup from the bottle. Now if they could just figure out a way to get rid of that annoying watery layer that always comes out first. [Brainiac]

Finally, research on why heirloom tomatoes are just better than all the others. Here comes the chemistry of volatile compounds. [Scientific American]

Attention Canadians: You may soon get to buy apples that won’t go brown after they’ve been cut. [Cnews]

To see the QR code on this glass, you’ll have to pour a pint of Guinness. [BoingBoing]

Slate takes on baby veggies – Are they the veal of the vegetable world? [Slate]

Cuttlefish are just SO unevolved. Pigments in their ink sacs haven’t changed for 160 million years. [iO9]

Top 10 newly discovered species of 2011 announced. List includes a sneezing monkey, a night-blooming orchid, and a walking cactus. [Science Daily] For coverage of 2010’s list, click here: [C&EN/Newscripts]

Ozymandias, senior med chemist

Fri, 25 May 2012 08:30 GMT

by Chemjobber

I met a janitor from a run-down lab
Who said: Two vast and peeling poster slides
Hang in the hallway. Near, on the bench slab,
Half torn, a wrinkled photo, with a frown,
And wrinkled lip, and sneer of cold command,
Tell that its subject well those structures read
Which yet survive, inked on these lifeless things,
The hand that drew them in the projects dead:
And on the white caption these words appear:
"Ozymandias, senior med chemist:
Look on my works, ye postdocs, and despair!"
Nothing beside remains. Round the decay
Of that empty building, tragic and bare
The clear hood sashes still rattle away.

with apologies to Shelley

Interview: “Taking Organic Chemistry Is A Great Way To Develop Critical Thinking Skills”

Fri, 25 May 2012 08:21 GMT

A few weeks ago I had the chance to interview (via e-mail) an instructor of organic chemistry at a medium-size American school, who shared her insights about teaching and learning organic chemistry. Comments have been lightly edited by me (JA). Thanks to the anonymous organic chemistry instructor (OCI) for taking the time to participate.

JA: As an organic chemistry instructor, what are some of the most common mistakes you see students making?

OCI:

Not counting carbons.
Kicking out H as a leaving group rather than using a base to remove a proton
Wanting to focus on nomenclature, especially in Organic I. Hey, even I don't know all the IUPAC rules! I tend to quickly shift the focus of the course away from nomenclature

JA: What do you think are some of the key ingredients for success in organic chemistry ? Do you have one that's most important?

OCI:

Recognizing functional groups and learning the patterns. I always tell my students to try to not get intimidated by molecules (even if the molecule looks intimidating) because, sometimes, the bulk of the structure isn't involved in the reaction of interest. “A molecule will tell you what it wants to and can do”, I often say, “it's up to you to learn to recognize the message.”
Learn to simplify the question to everyday language, especially with mechanism type questions. Asking “what has happened here?” is a powerful question that can reveal the path to solving many problems.
This is probably the most important – I think taking organic chemistry is a great way to develop critical thinking skills, so not being averse to thinking is key. Many questions in organic chemistry require you to take the time to re-interpret the question, look at all aspects of the question, winnow out the unimportant aspects, then follow an “if this, then that” scenario. If you don't follow through, most often you will miss the point and the answer. It is very difficult to do well in organic chemistry if you hate being pushed to think or are a lazy thinker. You have to be wiling to be engaged.

JA: When you were learning, what were some of the biggest “roadblocks” you had on the way?

OCI:

Not learning the patterns. I think I wasn't told that there were patterns. To be honest, it wasn't until graduate school that I actually “got” organic chemistry. I really liked organic chemistry in college and I did really well in the course. I even went on to do research in synthesis after college, but it wasn't until graduate school, when I got thrown in the deep end learning vast amount of new material, honing my lab skills, and developing my sense of independence that I really learned what organic chemistry was all about. I was pushed to think deeply. It turns out organic chemistry wasn't that complicated after all. I just to look for the patterns. Sure, there were always things that don't fit the pattern. Learning to accept that was also something I had to learn.

JA: If you could wave a magic wand and get your students to do one thing better, what would it be?

OCI:

Practice, practice, practice. Do assigned problems honestly. Not just to say you've done them, but to use problems as a diagnostic tool to determine their own level of understanding and to help see the pattern. This ties in with #2 above.

JA: What the best thing about organic chemistry, in your opinion – what gets you excited about it?

OCI:

The problem-solving ability and creativity it nurtures. I love the challenge of having to think your way out of any problem and, of course, the satisfaction I feel when/if I get it right. I also appreciate the fact there is an explanation for everything (even if there is still a debate about it) and that there is very little that falls to subjectivity or explanation by majority vote involved in organic chemistry. I guess this is what science is all about.

JA: Any other perspectives or questions that I missed? You're anonymous, you can say what you like.

OCI: Can't think of anything here.

JA: Thank you so much for your time.

OCI: Glad to have an opportunity to share my thoughts and experience.

Are you an instructor (or student) of organic chemistry? Willing to be interviewed? I'd love to get your perspective. Your identity will be held in confidence unless you expressly desire otherwise.

Kindler, Liveris, Madeleine Jacobs all visitors to White House. Chemistry professors? Not really.

Fri, 25 May 2012 08:10 GMT

The Washington Post has done the country a service by tallying White House visitor logs and putting them in a searchable form.* Being a curious sort, I started to put the names of chemical luminaries into their database.

Disappointingly, I couldn't get any prominent professors of organic chemistry. Sanford, Jacobsen, Bertozzi and Breslow were all busts. (Maybe they were one of the people who didn't have to sign in, yeah, that's the ticket!) Daniel Nocera is a no-go, too. (See update below.)

Among pharma types, (your friend and mine!) Jeff Kindler has been to the White House many, many times. He first arrived on March 5, 2009 and visited 12 more times until his last visit on June 17, 2011. But Kindler has been active in politics for a while, I believe. (What was he doing at the White House after he was let go from Pfizer in December 2010? Who knows?) John Lechleiter, the CEO of Lilly has been to 1600 Pennsylvania Avenue a few times himself, although not nearly as many as Kindler. Lechleiter seems to hold the title for most prominent holder of a Ph.D. in chemistry (and most prominent process chemist!) to be invited to the White House. Merck CEO Ken Frazier, by contrast, seems to have been at the White House only once.

American Chemical Society CEO Madeleine Jacobs has been to the White House 8 times, with 3 of them being meetings with their relevant policy professionals. White House staffer Victoria Espinel (the "copyright czar") seems to show up in these logs on a regular basis. Once, she was in the room at the same time as Robert Massie, the president of CAS. For fans of C&EN, I'm disappointed to note that Rudy Baum hasn't appeared to have been to the White House.

Finally, our #chemjobs fibber Andrew Liveris (and his wife Paula) seem to be frequent visitors to the occupants of the White House with 19 visits. (See update 2) It gives me cold comfort that the two people in my little database search to have been at the White House are 1) the person who's laid off many, many chemists in his time and 2) the person who keeps telling the mainstream media how the country has a desperate shortage of chemical professionals.

Readers, try your hand out at the database and tell us in the comments who's been to the White House (use the "advanced search" feature.)

UPDATE: Lisa Jarvis of C&EN notes that Harvard's George Whitesides spends a lot of time (more than Liveris or Kindler!) at the White House.

UPDATE 2: An astute reader points out that Andrew Liveris is co-chair of the President's Advanced Manufacturing policy committee, and would be expected to visit the White House frequently.

*[I should take a moment and say that, within reason, there should be high levels of transparency for the behavior of elected officials. I don't really see this as a Democratic/Republican issue; I see this as a "those who have influence" versus "those who do not" issue.]

A Toxic Tale Of Serendipity

Fri, 25 May 2012 07:29 GMT

This post is from guest blogger Lila Guterman, senior editor for C&EN's Journal News & Community group, and was written for the “Our Favorite Toxic Chemicals” blog carnival.

I have long had a fondness for weird, complex, toxic natural products. (Witness three recent stories I assigned and edited.) So when ScienceGeist announced the “Our Favorite Toxic Chemicals” blog carnival, I knew I’d have to participate. It would give me the chance to tell the story of homobatrachotoxin.

The story begins in 1963, with a young NIH chemist, John W. Daly, taking a trip to Colombia at the request of his boss to investigate the chemistry of frog secretions. His discoveries would launch his career as a
chemical ecologist and pharmacologist, and would spur an outpouring of research into the toxin he discovered, batrachotoxin.

He published the chemical structure, the biological effects, and a partial synthesis, in 1971. Batrachotoxin and its natural analogs, homobatrachotoxin and batrachotoxinin A, are among the most toxic natural substances known. Just 200 ng kill a mouse in 8 minutes; the lethal dose for people is thought to be around 100 µg.

Daly and colleagues found that batrachotoxin binds to sodium channels, opening them. Researchers now use batrachotoxin to study how these channels interact with anesthetics, anticonvulsants, and antiarrhythmia agents.

Phyllobates terribilis. Credit: Micha Rieser

These alkaloid toxins are secreted by certain species of Colombian poison-dart frogs – so called because Indians in Western Colombia used their secretions to poison the tips of blow darts. The most poisonous frog, the bright yellow Phyllobates terribilis, secretes batrachotoxin at levels high enough to kill several people.

Daly developed an unorthodox method for deciding whether to collect a frog in the wild – one he was lucky, or prudent, enough not to try on Phyllobates terribilis: “It involved touching the frog, then sampling it on the tongue. If you got a burning sensation, then you knew this was a frog you ought to collect,” he told the NIH Record, in 2002. In his work with South and Central American frogs, Daly and his collaborators ended up isolating more than 500 new natural products.

A series of chance occurrences led Daly to perhaps the most intriguing discovery of his career: that homobatrachotoxin is also secreted by a songbird that lives halfway around the world.

The New Guinea songbirds Pitohui dichrous (left) and Ifrita kowaldi contain batrachotoxin alkaloids such as homobatrachotoxin, previously found only in poison-dart frogs. Credit: Photos by John Dumbacher

In 1989, John P. Dumbacher, then a graduate student in ornithology, was studying birds of paradise in New Guinea. His nets sometimes caught other birds, including a songbird called the hooded pitohui (Pitohui dichrous).

“These are large birds that can cut your hands, and as I struggled to free them, they bit and scratched my hands,” he told COSMOS Magazine this year. “These little scratches really stung, so I just put my fingers in my mouth to clean the cut, and after a minute or so my lips and tongue began to tingle and burn.”

Dumbacher once described the feeling in the pages of C&EN as “a lot like tasting hot chili peppers or touching a 9-volt battery.”

Dumbacher had trouble finding a chemist who would take seriously the idea that a bird could be poisonous. (He’d originally been skeptical, too: It took a second trip to New Guinea, in 1990, to convince himself that the birds were secreting toxins, he told Smithsonian ZooGoer.) Only Daly agreed to look at the secretions, and he immediately recognized the mass spectrum of a batrachotoxin.

In 1992, Dumbacher, Daly, and colleagues published their discovery in Science: homobatrachotoxin in the skin and feathers of three species in the genus Pitohui. The levels of the toxin were far lower than in the frogs, but its presence was still startling: How could these two unrelated animals, separated by oceans and thousands of miles, both secrete a single complex steroidal toxin?

It was also the first paper to report a toxic substance from a bird.

“People were stunned by that first report,” Paul J. Weldon, of the Smithsonian Institution, told C&EN in 2000. “It floored the heck out of me.”

In 2000, the two researchers, with colleague Thomas F. Spande, reported the presence of homobatrachotoxin
in another bird in New Guinea. This time it was the blue-capped ifrita, from a different genus. Their finding raised the question: Do birds engage in chemical defense more commonly than scientists had realized?

Daly and Dumbacher also wanted to know where this outrageous organic compound came from. They realized the frogs and birds must both eat something that carried the toxin.

A hint came in 2004: After more than a decade of studying the pitohui diet, they finally found a group of beetles in the genus Choresine that carry batrachotoxin – and at high concentrations. (They found them thanks to a tingling sensation that local villagers reported from contact with the beetles.) The researchers think that the poison-dart frogs must eat relatives of the Choresine beetles that live in Colombia, though they have yet to discover them. Field research in that country has become far more difficult, due to its long-lasting civil war.

Still more questions remain unanswered: How did the birds and frogs evolve to sequester the highly potent alkaloid poison and to avoid its toxic effects? How do the beetles synthesize the toxin? Or do they eat something else that in turn made the batrachotoxin?

Dumbacher, who is now an ornithologist with the California Academy of Sciences, continues to study these questions.

But Daly’s work is done. He died in 2008. (NIH hosted and videotaped a tribute to his life and prodigious career. The Journal of Natural Products also published a special issue in his and another deceased scientist’s honor.)

Postscript:

ScienceGeist asked carnival participants to “talk about a toxic chemical that plays some nontoxic role in their lives.” This one doesn’t play a nontoxic role for me – apart from being the story that got away.

I first learned of the story behind the batrachotoxins in 2000 – it may even have been from the C&EN story I’ve already linked a few times.

I was fascinated. I immediately called John Daly and interviewed him about the work. But at the time, I couldn’t find a way to wrangle it into a story that would work for the weekly publication where I was a science reporter. I’ve wanted to write about it for years but never found a way. I’m glad that C&EN profiled
Daly in 2006, before I joined the staff.

The name of the toxin perhaps should have rung a bell for me back in 2000. The first total synthesis of the molecule had been published in 1998. It was by my undergraduate adviser, Yoshito
Kishi. One of the coauthors had been a labmate of mine. I wish I could remember whether he’d been working on it during my years in the lab, in ‘93 and ‘94.

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