Erowid receives semi-regular notes from well intentioned visitors telling us that yerba maté does not contain caffeine, but instead contains a chemical called "mateine". After looking into the issue several times in the past, we have decided to write a brief description of why we believe that caffeine is the major psychoactive chemical in yerba maté and mateine is simply another name for caffeine.

It appears that several articles available online are completely bogus, having been either faked by a vendor to improve sales or a yerba mate fan in order to explain why they liked yerba maté tea and not other types of caffeinated tea. Almost all of the online discussions or mentions of mateine lead back to a single source, Daniel Mowrey. Mowrey provides no credible scientific references for his claims about mateine, mentioning only a couple of institutes who have reportedly done work with yerba mate. The only expert he cites, Dr. Jose Martin, when contacted by the author of an article about yerba mate, "said there is no unique chemical structure for mateine and that yerba mate contains caffeine, just like coffee".²

One of the errors in the literature upon which the "mateine" claims are based is the claim that mateine is a stereoisomer of caffeine. This stands out because, there are no stereoisomers of caffeine. In order to have a stereoisomer, a chemical nearly always (see below) must have a stereocenter. The caffeine molecule lacks a stereocenter, does not have one of the unusual special cases, and thus there are no stereoisomers. This error, repeated widely, has had no foundation in the scientific literature.

There is no stereoisomer of caffeine. It's that simple.



One thing to note is that people report slightly different effects from drinking yerba maté than from drinking green tea, although the exact differences have not been well documented. A common misunderstanding exists that this necessarily means that yerba maté does not contain caffeine as a major psychoactive alkaloid. Caffeine is a xanthine. Yerba maté contains two other xanthines (caffeine-like compounds) theobromine and theophylline that have their own effects. It is very possible for different experiential effects to be the result of different levels of these three compounds or of other variables, including differences in dosage, differences in accompanying minerals or related alkaloids, expectations, taste, smell, etc. Mint tea or gum, for instance, can be stimulating or refreshing partially based on smelling the volatile fragrance oil. It is not known exactly in what ways yerba maté is experientially different from Chinese teas or what accounts for those differences.

---

The chemistry journal search engine Scifinder uses the Chemical Abstract Database, which is one of the most comprehensive resources for chemical information. The entry (below) for mateine states that an alternate name for mateine is "caffeine".

Registry Number: 	1407-79-0
CA Index Name: 	Mateine (8CI)  
Formula: 	Unspecified
STN Files: 	PROMT
(Additional Information is available through STN International. 
 Contact your information specialist,
 a local CAS representative, or the CAS Help Desk for Assistance)
Class Identifier: 	Manual Registration
No Structure Diagram Available
No References
Database REGISTRY
other names include:
1H-Purine-2,6-dione, 3,7-dihydro-1,3,7-trimethyl-; Caffeine ;
1,3,7-Trimethyl-2,6-dioxopurine; 1,3,7-Trimethylxanthine;
3,7-Dihydro-1,3,7-trimethyl-1H-purine-2,6-dione; 7-Methyltheophylline; Alert-Pep; 
Cafeina; Caffedrine; Caffein; Cafipel; Diurex; Guaranine; Koffein; Mateina;
Methyltheobromine; No-Doz; Refresh'n; Shape Plus; Stim; Thein; Theine; Tri-Aqua

The below quote is one of those most often cited as evidence that mateine exists and is the primary psychoactive ingredient in yerba maté. This contradicts most other evidence that caffeine is plentiful in yerba maté, and that mateine does not exist. It is included here in order to document what is believed to be false information about maté.

"Chemical assays on mate have traditionally looked for caffeine. In such tests mateine, being a simple stereoisomer of caffeine, would test positive. Until recently nobody has looked at the exact structure of the molecule -- and, to my knowledge, nobody in the United States has ever made the attempt. Researchers at the Free Hygienic Institute of Hamburg, Germany, concluded that even if there were caffeine in mate, the amount would be so tiny that it would take 100 tea bags of mate in a six ounce cup of water to equal the caffeine in a six ounce serving of regular coffee. They make the rather astute observation that it is obvious that the active principle in yerba mate in not caffeine! But then, we know for sure it is not caffeine, for caffeine is not present at all.

Mateine has a unique pharmacology and it is unfair to compare it to caffeine (incidentally, guarana may not contain caffeine either -- it may contain something that could by called guaraneine -- however that substance looks like it is more deleterious that caffeine!) Mateine appears to possess the best combination of xanthine properties possible. For example, like other xanthines it stimulates the central nervous system; but unlike most, it is not habituating or addicting. Likewise, unlike caffeine, it is a mild (not strong) diuretic, as are many xanthines. It relaxes peripheral blood vessels, thereby reducing blood pressure without the strong presser effects on the medulla and heart exhibited by some xanthines. We also know that it improves psychomotor performance without the typical xanthine-induced depressant after effects. Dr. Jose Martin, Director of the National Institute of Technology in Paraguay, writes, 'New research and better technology have shown that while mateine has a chemical constituency similar to caffeine, the molecular binding is different. Mateine has none of the ill effects of caffeine.' And Horacio Conesa, professor at the University of Buenos Aires Medical School, states, 'There is not a single medical contradiction' for ingesting mate. Clinical studies show, in fact, that individuals with caffeine sensitivities can ingest mate without adverse reactions. -- Daniel B. Mowrey, PhD"