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Author: Subject: structure of galangol (alpinol)
Paddywhacker
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[*] posted on 9-3-2013 at 15:02
structure of galangol (alpinol)


I have inherited a number of packets of Sha Jiang Fen (galangal) powder, but haven't been able to find out much about it's constituents except that it contains galangol, also known as alpinol.

Neither of these names are in Chemspider, and Google is not much help, either.

The spice powder has a numbing, anesthetic effect on the tongue which is not to my liking for culinary purposes, so extracting the active ingredients might be of greater interest, if I only knew what they were.

Can anybody help?
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[*] posted on 10-3-2013 at 12:16


The only thing I could find on "alpinol" was Propranolol and alprazolam capsules. Hardly a culinary spice I would think. More like Indian Xanax...

http://www.indiamart.com/brenstem-bio-sciences/pharmaceutica...
http://en.wikipedia.org/wiki/Alprazolam
http://en.wikipedia.org/wiki/Propranolol




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[*] posted on 10-3-2013 at 17:03


Quote: Originally posted by Bot0nist  
The only thing I could find on "alpinol" was Propranolol and alprazolam capsules. Hardly a culinary spice I would think. More like Indian Xanax...

http://www.indiamart.com/brenstem-bio-sciences/pharmaceutica...
http://en.wikipedia.org/wiki/Alprazolam
http://en.wikipedia.org/wiki/Propranolol


Alpinol (galangol) is a constituent in galangal spice, also known as Sha Jiang Fen.
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[*] posted on 10-3-2013 at 19:42


Google's Scholar search is more helpful in these kinds of searches.

Many papers concentrate on galangal extract medicinal properties but a few cite 1'-acetoxychavicol acetate (CAS: 52946-22-2) as a 2/3 to 3/4 predominant specie in ethanol extracts.
1AcChavicolAc.gif - 2kB
An unencumbered document is available from the original authors.

Antimicrobial properties and action of galangal (Alpinia galanga Linn.) on Staphylococcus aureus
Jirawan Oonmetta-areea, Tomoko Suzukib, Piyawan Gasalucka, Griangsak Eumkebc
http://dx.doi.org/10.1016/j.lwt.2005.06.015
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[*] posted on 11-3-2013 at 01:20


Thanks very much. That was unexpected. As galangal is the powdered root of a member of the ginger family I had expected the active ingredient to be similar to zingerone. This is quite different.
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[*] posted on 12-3-2013 at 00:05


That is not galangol. Galangol is a flavone, check its structure!
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[*] posted on 12-3-2013 at 09:34


Quote: Originally posted by Nicodem  
That is not galangol. Galangol is a flavone, check its structure!
Cites, plz.

While alpinia galanga contains dozens of terpenes, both free and bound as glycosides, the "pungent principal", 1'-acetylchavicol acetate, is most germane and the most often cited. Terpenoids predominate in leaf extracts. Select citations for root or 'rhizome' extracts, particularly since the root is what we like to eat in Thai food.

The paper cited above uses a polar extract (ethanol) rather than steam distillation since the pungent principal is prone to rearrangement.

Another paper is explicit about the principal's gustatory effect and sigmatropic rearrangement in aqueous media.
Pungent Principal of Alpinia galangal (L.) Swartz and Its Applications
J. Agric. Food Chem., 1999, 47 (4), pp 1657–1662
DOI: 10.1021/jf9808224

Springer-Link gives you a definitive answer in this table image from Flavor Chemicals with Pungent Properties, page 200, DOI: 10.1007/978-1-4615-4693-1_18

galangalConstituents.png - 55kB
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[*] posted on 13-3-2013 at 07:22


I made a mistake. I confused galangol with galangin which is a flavone isolated from Alpinia galanga and some other plants.

SciFinder does not list galangol as a compound. Paddywhacker, what is the reference claiming this compound name? Are you sure it is not misspelled?

One database that lists galangol as a constituent of the rhizome of Alpinia galanga and Alpinia officinarum is Dr. Duke's Phytochemical and Ethnobotanical Databases. As is common with this database, it gives a secondary source as a reference: List, P.H. and Horhammer, L., Hager's Handbuch der Pharmazeutischen Praxis, Vols. 2-6, Springer-Verlag, Berlin, 1969-1979.
It also cites the same reference for the presence of galangin in the the rhizome. Galangin is also present in A. officinarum, Acorus calamus, Glycyrrhiza glabra, Origanum vulgare and Populus tacamahacca.

I find this "galangol" a bit suspicious. It pretty much sounds like a German transliteration of galangin. I would not be surprised if the seminal article describing the isolation and characterization of galangin (supposedly done in the year 1881) was in German and the original name was galangol.

A review of the phytopharmacology and phytochemistry of Alpinia galanga can be found in the Indian Journal of Natural Products and Resources, 1 (2010) 143-149. It also mentions no constituent called galangol. No alpinol either, but it does mention alpinin.




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[*] posted on 13-3-2013 at 22:20


Quote: Originally posted by Nicodem  
I made a mistake.

Me too.

Simply, it is complicated.

As you examine the available citations, you understand that while there may be a major components, that it is not only the carrots that make the stew.

As a metaphor, I note that strawberries and cilantro leaf have a few common fragrance notes, and that one is complimented by a small amount of the other, except for those who are sensitive to the C8-C10 α-β unsaturated aldehydes of the latter.

Yes, there are flavinoids in galangal root. I am too lazy to post cites at the moment. Surely someone else can do better.
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[*] posted on 18-3-2013 at 23:45


Thanks for the feedback. It looks as if galangol and alpinol are archaic names for the mixed resin - "The resin causing the pungent taste (formerly called galangol or alpinol) consists of several diarylheptanoids and phenylalkanones (the latter are also found in ginger and grains of paradise)" from here.
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