Synephrine

Synephrine

Names
Preferred IUPAC name 4-[1-Hydroxy-2-(methylamino)ethyl]phenol
Other names p-synephrine
Identifiers
CAS Number	94-07-5 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29081 Y
ChEMBL	ChEMBL33720 Y
ChemSpider	6904 Y
ECHA InfoCard	100.002.092
KEGG	D07148 Y
PubChem CID	7172
UNII	PEG5DP7434 Y
CompTox Dashboard (EPA)	DTXSID0030588
InChI InChI=1S/C9H13NO2/c1-10-6-9(12)7-2-4-8(11)5-3-7/h2-5,9-12H,6H2,1H3 Y Key: YRCWQPVGYLYSOX-UHFFFAOYSA-N Y InChI=1/C9H13NO2/c1-10-6-9(12)7-2-4-8(11)5-3-7/h2-5,9-12H,6H2,1H3 Key: YRCWQPVGYLYSOX-UHFFFAOYAW
SMILES CNCC(O)c1ccc(O)cc1
Properties
Chemical formula	C9H13NO2
Molar mass	167.21 g/mol
Appearance	colorless solid
Melting point	162 to 164 °C (324 to 327 °F; 435 to 437 K) (R-(−)-enantiomer); 184 to 185 °C (racemate)
Solubility in water	soluble
Pharmacology
ATC code	C01CA08 (WHO) S01GA06 (WHO), QS01FB90 (WHO)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synephrine, or, more specifically, p-synephrine, is an alkaloid, occurring naturally in some plants and animals, and also in approved drugs products as its m-substituted analog known as neo-synephrine.^[1] p-Synephrine (or formerly Sympatol and oxedrine [BAN]) and m-synephrine are known for their longer acting adrenergic effects compared to epinephrine and norepinephrine. This substance is present at very low concentrations in common foodstuffs such as orange juice and other orange (Citrus species) products, both of the "sweet" and "bitter" variety. The preparations used in traditional Chinese medicine (TCM), also known as Zhi Shi (枳实), are the immature and dried whole oranges from Citrus aurantium (Fructus Aurantii Immaturus). Extracts of the same material or purified synephrine are also marketed in the US, sometimes in combination with caffeine, as a weight-loss-promoting dietary supplement for oral consumption. While the traditional preparations have been in use for millennia as a component of TCM-formulas, synephrine itself is not an approved over the counter drug. As a pharmaceutical, m-synephrine (phenylephrine) is still used as a sympathomimetic (i.e. for its hypertensive and vasoconstrictor properties), mostly by injection for the treatment of emergencies such as shock, and rarely orally for the treatment of bronchial problems associated with asthma and hay-fever.^[a]

There is a difference between studies concerning synephrine as a single chemical entity (synephrine can exist in the form of either of two stereoisomers, d- and l-synephrine, which are chemically and pharmacologically distinct), and synephrine which is mixed with other drugs and/or botanical extracts in a "supplement", as well as synephrine which is present as only one chemical component in a naturally-occurring mixture of phytochemicals such as the rind or fruit of a bitter orange. Mixtures containing synephrine as only one of their chemical components (regardless of whether these are of synthetic or natural origin) should not be assumed to produce exactly the same biological effects as synephrine alone.^[2]

In physical appearance, synephrine is a colorless, crystalline solid and is water-soluble. Its molecular structure is based on a phenethylamine skeleton and is related to those of many other drugs and to the major neurotransmitters epinephrine and norepinephrine.

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