June 13, 2022
I’m responsible for the “grapefruit effect”.
What molecule am I?
Image of Bergamottin 3D Image of Bergamottin

Furanocoumarins are organic compounds found in the seeds and fruits of many species of plants, notably in the families Rutaceae (citrus fruits) and Apiaceae (celery, carrots, and others). As the name suggests, the central structure of furanocoumarins consists of a furan ring fused to a two-ring coumarin system.

Psoralen1 and angelicin2 are unsubstituted furanocoumarins in which the furan and coumarin rings are fused in linear and angular orientations, respectively. Bergamottin and its oxidation products 6′,7′-dihydroxybergamottin3 (DHB) and 6′,7′-epoxybergamottin4 are psoralen derivatives that have geraniol-derived side chains attached at the 5-position. Bergamottin is named after the bergamot orange (Citrus bergamia); it was first isolated from bergamot oil in 1937 by Ernst Späth and Paul Kainrath at the University of Vienna.

Bergamottin plays a role in the lives of many people. It and DHB inhibit the cytochrome P450 enzyme CYP3A, thereby slowing or preventing the metabolism of lovastatin, simvastatin, atorvastatin, and other “statin” drugs that decrease the formation of low-density lipoprotein (LDL) carriers of cholesterol in the body. Bergamottins are particularly abundant in grapefruit, which is why statin labels advise against consumption of the fruit or its juice close to the time the drugs are taken.

The oxidized bergamottins and other grapefruit ingredients also inhibit the transport of talinolol5, a substrate for P glycoprotein, an important cell membrane component that removes foreign substances from cells. For more information on bergamottin and its derivatives, see this Science Direct entry.

1. CAS Reg. No. 66-97-7.
2. CAS Reg. No. 523-50-2.
3. CAS Reg. No. 145414-76-2.
4. CAS Reg. No. 206978-14-5.
5. CAS Reg. No.57460-41-0.

Bergamottin hazard information*

Hazard class** GHS code and hazard statement
Skin sensitization, category 1 H317—May cause an allergic skin reaction Chemical Safety Warning

*Most safety data sheets describe bergamottin as not a hazardous substance or mixture.
**Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.

Molecules from the journals

Cobalt(II) bromide1 (CoBr2) is a green crystalline solid that was known as long ago as 1883. In 1922, George L. Clark and Henry K. Buckner at the University of Chicago prepared it and its hydrates from cobalt carbonate and hydrobromic acid. Although its anhydrous form is green, its hydrates range in color from pink to blue.

CoBr2 has a long history as a catalyst for organic chemical reactions. This year, Grégory Danoun and colleagues at the Polytechnic Institute of Paris (Paliseau, France) reported that it is the only catalyst needed for simple, straightforward Negishi-type cross-couplings of aryl amides to produce alkyl aryl ketones.

(−)-Phaeocaulisin A2 is a guaiane-type sesquiterpene found in the Chinese ginger plant Curcuma phaeocaulis. The plant has long been used in traditional medicine; but in 2013, researchers began to study the isolated molecule for potential drug development. This year, Áron Péter, Giacomo E. M. Crisenza, and David J. Procter* at the University of Manchester (UK) reported an enantioselective total synthesis of (−)-phaeocaulisin A in 17 steps with 2% overall yield from commercially available starting materials and reagents.

1. CAS Reg. No. 7789-43-7.
2. CAS Reg. No. 1443004-41-8.

Molecules from the journals

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Bergamottin fast facts

CAS Reg. No. 7380-40-7
7H-Furo[3,2-g][1]benzopyran-7-one, 4-{[(2E)-3,7-dimethyl-2,6-octadien-1-yl]oxy}-
Empirical formula C21H22O4
Molar mass 338.40 g/mol
Appearance White crystals or powder
Melting point 55–56 °Ca
Water solubility ≈10 mg/L

a. Some sources report 59–60 °C or 75–80 °C.

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