What molecule am I?
Adrenaline—known in the medical community as epinephrine—is referred to in the vernacular as the “fight-or-flight” molecule. As adrenaline, it is a hormone; as epinephrine, it is a drug.
The history of adrenaline/epinephrine in the literature goes back to at least 1904, when Hooper Albert Dickinson Jowett at Wellcome Chemical Research Laboratories (London) wrote an article titled “The Constitution of Epinephrine”. Jowett confirmed the formula of epinephrine as C9H13NO3 and cited work done from 1897 to 1901 on substances called “epinephrin”, “suprarenin”, and “adrenalin”, all of which turned out to be the same material.
In 1905, T. B. Aldrich at Parke, Davis & Co. (Detroit) reported that adrenalin (his spelling) is the active principle of the suprarenal glands, which are now customarily called the adrenal glands. Aldrich summarized the long history of identifying the adrenal glands and their active ingredient, including the work that established the empirical formula, progress toward elucidating the structural formula (the correct one was first proposed by Jowett), and attempts to synthesize the molecule.
In 1904, Friedrich Stolz at Farbwerke Hoechst (Frankfurt am Main, Germany) had synthesized adrenolone1, the ketone form of adrenaline. This was followed in 1906 by his synthesis of adrenaline itself, which he called suprarenine. At about the same time, Henry Drysdale Dakin at the University of Leeds (UK) also synthesized adrenaline.
The biosynthesis of adrenaline/epinephrine begins with L-tyrosine2 and proceeds via enzymatic reactions through L-dihydroxyphenylalanine3 (L–DOPA), dopamine4, and norepinephrine5. Of all the researchers who worked out the biosynthesis, the most prominent was Julius Axelrod6 at the National Institutes of Health (Bethesda, MD) who elucidated the final methylation step.
In the body, adrenaline is primarily secreted in the adrenal medulla. It is released by exercise and emotional responses, especially fear and other negative reactions. It can also trigger enhancement of long-term memory. As a drug, epinephrine is used as an injectable to treat medical conditions such as anaphylaxis, cardiac arrest, croup, and asthma. Despite its presence in the body and use as drug, adrenaline is an extremely toxic compound; see the hazard information table.
For more information about the early history of adrenaline/epinephrine, see an account by Greer Arthur at North Carolina State University (Raleigh).
1. CAS Reg. No. 99-45-6.
2. CAS Reg. No. 60-18-4.
3. CAS Reg. No. 59-92-7.
4. CAS Reg. No. 51-61-6.
5. CAS Reg. No. 51-41-2.
6. Axelrod shared the 1970 Nobel Prize in Physiology or Medicine for his work on catecholamine neurotransmitters.
Adrenaline hazard information
| Hazard class* | GHS code and hazard statement | |
|---|---|---|
| Acute toxicity, oral, category 3 | H301—Toxic if swallowed |  |
| Acute toxicity, dermal, category 2 | H310—Fatal in contact with skin | |
| Eye irritation, category 2A | H319—Causes serious eye irritation |  |
| Acute toxicity, inhalation, category 3 | H331—Toxic if inhaled | |
*Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.
Adrenaline fast facts
| CAS Reg. No. | 51-43-4 |
| SciFinder name | 1,2-Benzenediol, 4-[(1R)-1- hydroxy-2- (methylamino)ethyl]- |
| Empirical formula | C9H13NO3 |
| Molar mass | 183.20 g/mol |
| Appearance | White crystals or powdera |
| Melting point | 211–212 °Cb |
| Water solubility | 180 mg/L (20 °C) |
a. Turns brown when exposed to air.
b. Decomposes at 215 °C when heated rapidly.
MOTW update
Sulforaphane1, the Molecule of the Week for May 24, 2011, is an isothiocyanate biomolecule produced by the enzymatic breakdown of glucosinolates in many plants, especially the cruciferous vegetables broccoli, cabbage, and Brussels sprouts. Last month, Sachin Sharma, Rakesh Sharma*, and Anil Kumar Verma at the Dr. Yashwant Singh Parmar University of Horticulture and Forestry (Solan, India) published a review of the beneficial effects of sulforaphane on the gut–brain axis, through which it can alleviate inflammatory bowel disease, gut dysbiosis, neuroinflammation, and neurodegenerative diseases.
The authors report that the beneficial effects occur because sulforaphane modifies many signaling pathways (e.g., inhibition of the NF-κB family of transcription factor protein complexes), activates the nuclear factor erythroid 2-related factor 2 (NRF2) antioxidant pathway, and regulates macrophage polarization toward an anti-inflammatory phenotype.
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.
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