Book Review: Gulp

Note: For other reviews, check out Neurotic Psych, Science News, the New York Times, or the Boston Globe.

It took a bit longer than anticipated to finish Mary Roach's new book Gulp: Adventures on the Alimentary Canal.  Not any fault of hers - the book reads glibly enough, with just enough science to hold my interest (and just enough yuuuckk for wider audience appeal!).

Other reviews (see above) have explored the book's structure, which jokes hit or miss, and whether it holds water compared to Roach's other works. I'm going to take a slightly different take:

Gulp is a chemistry love story, wrapped in fart jokes and gallows humor.

As before, I'm just going to jump around to different chapters for moments I unexpectedly learned something about the unique chemistry of taste, smell, digestion, and excretion.

Page 44: "Pyrophosphates have been described [to author Roach] as 'cat crack.'"
(Finicky eater? Add some phosphates!)

Page 56: "A serving of liver provides half the RDA for vitamin C, three times the RDA for riboflavin, nine times the vitamin A in the average carrot, plus good amounts of vitamins B12, B6, and D, folic acid, and potassium."

"What's the main ingredient in dog food palatants? Liver."

Page 73: Huh: L-cysteine extracted from human hair has been used to make fake soy sauce.

Page 110: Baby saliva contains extra lipase, to compensate for "...the newborn's high-fat, 100% whole-milk diet."

Page 111: Fabric softener works by "...ever so gently digesting the fibers" using enzymes.
[Interestingly, howstuffworks.com, Wikipedia, and Answers.com seem to disagree, attributing the effect to static dispersal]

Page 142: Why does fruit crunch? "When you bite into an apple, the flesh deforms, and at a certain moment the cell walls burst."

Page 175: Oysters go into shock at low pH. Thus, "Researchers who need to sedate crustaceans use seltzer water."

Page 226: Apparently, in the early days of NASA space-flight, researchers expressed real concerns over capsule explosions due to methane and hydrogen gas produced during astronaut digestion.

Page 234: "Bean gas" results from complex oligosaccharides passing through the stomach and fermenting in the small intestine.

Page 245: Three sulfurous compounds contribute to most human flatulence odor: hydrogen sulfide, methanethiol, and dimethyl sulfide (the redolent-of-farts haze formed after a successful Swern oxidation.)

Page 247: Bismuth subgallate pills "...reduce 100% of sulfur gas odor, [functioning like an] 'internal deodorant.'"

Page 263: More on hydrogen sulfide, the "...hottest area in biomedicine right now: it's a gastrotrasmitter, a signaling molecule, [and] it has tremendous therapeutic value."

Page 275: Rats and rabbits engage in autocoprophagia - eating their own feces - as a method of supplementing vitamins (B5, B7, B12, thiamine, riboflavin) produced only by bacteria in their intestines.

Page 316: When processing "samples" for a stool transplant, a blender is modified to deoxygenate and store the material under nitrogen, thus promoting survival of anaerobic gut bacteria.

Overall, I really enjoyed the book, though I couldn't escape feeling that certain chapters (4, 11, 16?) had been shoehorned in from other projects only tangentially related to these "alimentary adventures." One interesting thing differentiating Roach's writing involves asides* to the reader, giving one the feeling that you're leaning in for a secret bit of wisdom...or an extra-terrible pun.

Seeing that Mary's last few books have dealt with (decidedly dirty) topics like death and digestion, I can only assume the next book will be titled Waste, and will uncover the exciting science of garbage and landfills.

If she writes it, I'll be first in line for a copy.

*Seriously, I know I'm supposed to 'kill my darlings' in writing, but I can't resist doing this sometimes...**
**Nor, apparently, can I resist ellipses. Dangit.

One More for the Road

OK, between my last post and that B.R.S.M. post, we've covered soda, wine, beer, carrots, salmon sperm, bone meal, coffee, and whiskey. If you include his comments, we can toss wool, almond meal, clay, and urine into the mix. But a recent J. Med. Chem. abstract may take the cake for me...

Poop.

Yup, here's the abstract, graphic and everything:

Source: J. Med. Chem. 2012, ASAP

What's the cecum, you ask? Great question! It's a "pocket" of large intestine, immediately following the small intestine and just before the colon. Apparently, it's renowned for two things: a high level of gut flora, and an anaerobic environment. When metabolism / fate scientists want to see what happens to an intestinal prodrug, this model comes into play.

Here's the prep, "fresh" from the Supporting Information:

"A solution of phosphate buffer (50 mM, pH 6.8) was prepared and deoxygenated by bubbling nitrogen for ten minutes. Male Sprague-Dawley rats were sacrificed and the cecum was exposed. The cecal contents were removed and used to make a 10% w/v suspension in the oxygen free buffer."

The microbe-rich slurry, after incubation with the compound at 37 degrees C with exclusion of oxygen, reduces down disulfide bonds, azo groups, even nitro aromatics to the parent anilines in "just a few hours."

Dunno about you, but I still think I prefer ol' Zn / AcOH. Probably smells a bit better, anyway.

Beetle Brood Balls Breed Polycyclic Puzzle

Tripartilactam: Confounding ChemDraw since 2012.

Natural product isolation chemists find fascinating molecules in wild, unexpected places. Hippo sweat. Deep-sea hydrothermal vents. Horse urine. Even maple syrup refining produces new compounds that chemists hope could be the next wonder drug. But a new paper from Org. Lett. ASAP brings forth a new discovery arena for me: dung beetles. Specifically, the giant balls of, well . . .poop, that they push around, then lay their eggs in.

Dung beetles with brood ball

Korean researchers have isolated tripartilactam from a Streptomyces species living in the beetles' brood ball, which they broke apart, cultured, and fractionated. Although the compound has no real biological activity, look at that structure: an 18-4-8 tricycle! Now, cyclobutanes are found in natural products all the time, from sceptrin to ladderanes, but usually not as a "bow-tie" bringing together two huge macrocycles. These scientists figure that a larger polyunsaturated structure was knit together by bacterial enzymes called polyketide synthases, followed by a light-initiated [2+2] to snap the cyclobutane shut.


Chemistry Note: Did you see that 18-4 trans ring juncture? Normally, that species would be far too strained to exist in anything below an 8-4 system. However, in a ring as large as 18, even with the rigid geometry enforced by the lactam and polyolefin chain, there's still enough wiggle room to accomodate this odd duck.