Here's one argument that mate contains caffeine, and mateine does not exist:
http://www.erowid.org/plants/yerba_mate/yerba_mate_chemistry1.shtml
The article says that the reason the effects of mate differ from those of green tea or coffee is that mate contains other xanthines: theobromine and theophylline. It says that all the people parroting info about mate NOT containing caffeine are misinformed by the same article.
And more from the same source about caffeine content by brewing style:
http://www.erowid.org/plants/yerba_mate/yerba_mate_chemistry2.shtml
Are there other sources which make the same argument?
I am certainly not finding the chemical structure of mate on google images.
After this search I am beginning to think mateine does not exist and I have been taken for a ride. And perpetuating the ride? Is mateine real? Maybe not.
EDIT July 23
I searched for Dr Jose Martin of the Institute of Technology in Paraguay, who it seems is quoted a bit around the web but does not have his own presence....anyway I found another anti-mateine argument and this one seems to be the clincher: caffeine, because the molecule has no stereocenter, can have no stereoisomer. This is basic chemistry and verifiable by looking at the molecule.
http://www.erowid.org/plants/yerba_mate/yerba_mate_chemistry1.shtml
An alternet page that admits the quote is "attributed" to the said doc:
http://www.alternet.org/environment/20510
An interesting article:
http://www.miyerbamate.com/content/Yerba_Mate_Nutrition_and_Health.htm
Yerba Mate, Nutrition and Health
Yerba Mate: For Better Health
By Daniel Mowrey, Ph.D.
--South American herb
--natural stimulant devoid of side effects and toxicity
--invigorator of the mind and body, a natural source of nutrition
--known by primitive Guarani Indians of Paraguay and Argentina
--most common ingredient in household cures
--"In modern Argentina and Paraguay, however, Mate tea has become almost pathologically ritualized in a manner reminiscent of coffee and tea abuse in Western and Eastern countries. Among the native Guarani, on the other hand, the natural use of Mate for healthful purposes has persisted. They use it to boost immunity, cleanse and detoxify the blood, tone the nervous system, restore youthful hair color, retard aging, combat fatigue, stimulate the mind, control the appetite, reduce the effects of debilitating disease, reduce stress, and eliminate insomnia."
--Flex paraguariensis
--evergreen member of the holly family
--grows wild in Argentina, Chile, Peru, and Brazil
--most abundant in Paraguay where it is also cultivated
--classified vaguely, according to Western herbal medicine, as aromatic, stimulant, bitter, aperient (laxative), astringent, diuretic, purgative, sudorific (sweat inducing), and febrifuge (fever reducing)
CONSTITUENTS
--numerous vitamins and minerals
--usual array of resins, fiber, volatile oil, and tannins
--carotene; vitamins A, C, E, B-1, B-2 (("and B-complex"??? this makes me loose faith in the nutritionist))), riboflavin; nicotinic acid; pantothenic acid; biotin; magnesium; calcium; iron; sodium; potassium; manganese; silicon; phosphates; sulfur; hydrochloric acid; ???? chlorophyll; choline; and inositol
--1964 Pasteur Institute and the Paris Scientific Society concluded that Mate contains practically all of the vitamins necessary to sustain life
--WILL PASTEUR INSTITUTE AND PARIS SCI SOC REPRESENTATIVES PLEASE STEP FORWARD
--mateine "probably contributes little, if anything, to the overall activity of the plant, but has drawn a disproportionate share of speculation"
--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 6-ounce cup of water to equal the caffeine in a 6-ounce serving of regular coffee ????
--one effect shared in xanthines: smooth muscle relaxation-->"good clinical dilators of the bronchi and hence useful in the treatment of asthma"
--stimulates the central nervous system
--not habituating or addicting
--it induces better sleep
--mild diuretic
--relaxes peripheral blood vessels-->lowers BP
--improves psychomotor performance without the typical xanthine-induced depressant after effects
--then in the article comes the very same Jose Martin quote: I have ceased to believe it
--WILL JOSE MARTIN PLEASE STEP FORWARD
--repair damaged and diseased gastrointestinal tissues
--tx for constipation
--nervous tonic: stimulating a weakened/depressed nervous system, sedating an overexcited one
--"Our knowledge of Mate's effects is currently limited to observations of behavior changes such as more energy and vitality; better ability to concentrate; less nervousness, agitation, and anxiety; and increased resistance to both physical and mental fatigue. Improvement in mood, especially in cases of depression, often follows drinking aspects of Mate is that it does not interfere with sleep cycles; in fact, it has a tendency to balance the cycles, inducing more rapid eye movement (REM) sleep when necessary, or increasing the amount of time spent in delta states (deep sleep)."
unfiltered from here down
I don't believe a word they say is based on science
show me the science
CARDIOVASCULAR EFFECTS
Heart Ailments of all kinds have been treated or prevented through Yerba Mate use. Yerba Mate supplies many of the nutrients required by the heart for growth and repair. In addition, it increases the supply of oxygen to the heart, especially during periods of stress or exercise. Mate has become a favorite of body builders and anyone interested in the health benefits of exercise. The metabolic effects of Mate appear to include the ability to maintain aerobic glycolysis (breakdown of carbohydrates) during exercise for longer periods of time. This results in burning more calories, increasing cardiac efficiency, and delaying anaerobic glycolysis and the resulting buildup of lactic acid during exercise. Reports of Mate reducing blood pressure are not uncommon.
EFFECTS ON THE IMMUNE SYSTEM
A consistent observation in most South American literature on Mate is that it increases the immune response of the body, stimulating natural resistance to disease. This results in a nourishing and strengthening effect on the ill person, both during the course of the illness and during convalescence, sometimes dramatically accelerating recovery times. Exact mechanisms of Mate's action have not been worked out, but they involve both a direct action against infectious organisms, and an effect on overall resistance to disease. The nutritional content of the plant probably plays a major role here, but it is also probable that other constituents contribute to the action by stimulating the activity of white blood cells.
NUTRITIONAL PROPERTIES
The interaction of the many nutrients in Mate have never been systematically studied. But the stories surrounding the nutritional application of Mate tea are nothing short of amazing. Mate is often used as a staple food, sometimes substituting for such important foods as bread and vegetables. It easily eliminates the sensation of hunger and can impart as much invigoration as a full meal, according to the well-known Chilean herbalists J. Zin and R. Weiss. Peace Corps workers have reported cases in which large groups of natives remain in good health for extended periods of drought and famine, even though they eat only one small meal per day. How so? By drinking copious amounts of Yerba Mate tea. Some natives spend their entire lives on such a diet and live to very advanced ages, sometimes in excess of 100 years. South American governments have adopted the practice of encouraging mothers, especially in the poorer regions, to include Yerba Mate in the diet of their school-age children. the tea. This may be a direct or indirect result of increased energy.
Dr. Mowrey received his doctorate in experimental psychology (with an emphasis on psychopharmacology) from Brigham Young University in Provo, Utah
http://www.erowid.org/plants/yerba_mate/yerba_mate_chemistry1.shtml