Chemistry and Life

Medicinal chemistry. Pharmacology. Toxicology. Environmental sciences.


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If you are going to prepare an infographic for the world to see, please get the chemistry right

Infographic structure (top) and penicillin G (bottom)

Infographic structure (top) and penicillin G (bottom)

As I was writing yesterday’s comments on antibiotics, I referred to a recent World Health Organization report on antibiotic resistance. This report is a major publication intended for a worldwide audience, and it has gotten international media attention.  Accompanying it is a two-page infographic to summarize the important findings of the report.  Illustrating the infographic is the chemical structure of a penicillin.  Or, at least, if it is supposed to a penicillin, the chemical structure is wrong.  It looks like it is intended to be penicillin G (benzylpenicillin).  However, the beta lactam portion is missing an oxygen atom, the two methyl groups on the right side are missing, and the “PhCh2” should be “PhCH2“.

So… a little unsolicited advice for the WHO:  If you are going to prepare an infographic containing a chemical structure for the whole world to see, please have a chemist review it first.  Thank you.


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Vitamins from meteorites

This paper describes the analysis of chemicals in a collection of meteorites. The meteorites were all of a type called carbonaceous chondrites. They are an uncommon variety which are distinctive for their content of organic compounds, including amino acids and common heterocyclic compounds – some of the basic building blocks of life on Earth. In this study, the researchers found a variety of pyridine carboxylic acids in these meteorites. One of them is pyridine-3-carboxylic acid which is better known as niacin or vitamin B3.

In a nice bit of followup, the researchers posited a plausible mechanism for the production of pyridine carboxylic acids. Since pyridine and derivatives have been found in meteorites before (here, for example), they simply showed that proton-irradiation of pyridine in carbon dioxide rich ice, conditions that might have been encountered in the interstellar environment, produced niacin and other pyridine carboxylic acids.

This is all consistent with the body of research that indicates that many of the basic ingredients and building blocks for life may have come from extraterrestrial sources. As the researchers conclude, niacin “is a precursor to nicotinamide adenine dinucleotide, a likely ancient molecule used in cellular metabolism in all of life, and its common occurrence in CM2 chondrites may indicate that meteorites may have been a source of molecules for the emergence of more complex coenzymes on the early Earth.”


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“Chemical free” charcoal

"Chemical free" charcoal

“Chemical free” charcoal (click to enlarge)

I saw this at the grocery store recently.  It is “chemical free” charcoal.  That complex mixture of carbon, hydrocarbons, and other chemical compounds is claimed to be free of chemicals.  Taken at face value it is a nonsense claim; everything is made of chemicals.  What they really mean is that it hasn’t been treated with any kind of lighter fluid to allow it to be easily lit with a match.  However, that’s redundant to their “additive free” claim that’s printed right next to it.

So why do they make the “chemical free” claim?  Because it’s good marketing.  People see the words “chemical free” and think that it must be healthier.  Our society is primed to think that “chemicals = harmful” – to the extent that even a nonsense statement like “chemical free charcoal” is an effective marketing tool.

The irony is that even natural untreated charcoal, its smoke, and its soot all contain polycyclic aromatic hydrocarbons, some of which are notoriously carcinogenic.  One’s exposure to harmful chemicals is not going to be reduced in any meaningful way by buying “chemical free” charcoal.