September 19, 2022
I’m toxic to cattle and, eventually, to people.
What molecule am I?
Image of Ptaquiloside 3D Image of Ptaquiloside

Ptaquiloside1 is a natural norsesquiterpene glucoside toxin present in bracken ferns2 (Pteridium aquilinum and other species). In 1983, it was isolated and characterized by Kiyoyuki Yamada and colleagues at Nagoya University (Japan), the University of Tokyo, and JEOL Ltd. (Tokyo).

Ptaquiloside is a carcinogen and the cause of hemorrhagic disease and bright blindness in cattle and other livestock. It can enter the milk and meat of affected animals and is known to cause esophageal and gastric cancer in humans. In 2019, Lars Holm Rasmussen and co-workers at the University of Copenhagen elucidated the biochemical fate of ptaquiloside in cattle.

Ptaquiloside has been well studied and reported, including in Chapter 13 of Color Atlas of Diseases and Disorders of Cattle (3rd ed., 2011) and in several publications cited by in the 2000s and 2010s.

Although ptaquiloside is highly toxic, no safety data sheets for it are available.

1. SciFinder: Spiro[cyclopropane-1,5′-(5H)inden]-3′(2′H)-one, 7′a-(β-d-glucopyranosyloxy)-1′,3′a,4′,7′a-tetrahydro-4′-hydroxy-2′,4′,6′-trimethyl-, (2′R,3′aR,4′S,7′aR)-.
2. People who collect the edible ostrich fern (Matteuccia struthiopteris) must be careful to avoid bracken ferns that grow in the same temperate climates.

Molecule of the Future

Epetraborole1 is a bicyclic boron-containing compound that was disclosed in a 2008 international patent application by Stephen J. Baker and co-inventors at Anacor Pharmaceuticals (Palo Alto, CA; now part of Pfizer). It and related compounds were claimed to be useful for treating bacterial infections. 

Molecule of  the Future

In 2017, AN2 Therapeutics (Menlo Park, CA) was founded to commercialize pharmaceuticals for underrepresented infectious diseases. AN2, which went public in March of this year, licensed epetraborole from Pfizer to develop it as a treatment for a chronic mycobacterial lung disease that is acerbated by multidrug-resistant Mycobacteroides abscessus. A Phase 2/3 clinical trial on epetraborole was launched in May and is expected to be completed in 2025.

1. CAS Reg. No. 1093643-37-8.

MOTW updates

2,4,6-Trichloroanisole1 (TCA) was the Molecule of the Week for December 23, 2013. It is the molecule responsible for “cork taint”, which gives wine a musty smell and taste and is also known to contaminate other beverages and some foods.

This August, Luca Cappellin and colleagues at the University of Padua and Illycaffè sPa (Trieste, both in Italy) disclosed a method for screening green coffee beans for TCA contamination, a phenomenon known as the “Rio defect”. They used chemical ionization time-of-flight mass spectrometry with a Vocus2 ion source and an ion-molecule reactor to analyze 22 Coffea arabica bean samples, four of which exhibited the Rio defect according to a panel of cup-tasting experts. The results were available in 3 s and correlated strongly with the panel’s findings.

1H-1,2,3-Triazole was the Molecule of the Week for December 7, 2020. It is one of the four aromatic heterocyclic compounds with two carbon atoms, three nitrogen atoms, and two double bonds. In aqueous solution, it is in equilibrium with its 2H-tautomer.

This month, Xiaowei Song, Yifan Meng, and Richard N. Zare* at Stanford University (CA) reported that the 1,2,3-triazoles play a key role in converting carbon dioxide to formic acid. The authors sprayed microdroplets of an aqueous 1,2,3-triazole solution into a gas-phase reactor containing CO2; the droplets captured CO2 and reduced it to formic acid at the gas–liquid interface. The process was optimized to achieve yields of >80%.

1. CAS Reg. No. 87-40-1. 
2. Aerodyne Research, Billerica, MA.

Molecule of the Future

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Ptaquiloside fast facts

CAS Reg. No.87625-62-5
Empirical formulaC20H30O8
Molar mass398.45 g/mol 
AppearanceWhite powder
Melting point85–89 °C
Water solubilityHighly soluble
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