Where Aztecs Meet Scientists

19th Feb 2009

Corrine Burns, expert on Aztec herbal medicine

This article has generously been written specially for us by Corrinne Burns, Leicester School of Pharmacy, De Montfort University. You can read more of her work by exploring the articles in the right-hand menu.

Guavas and passion fruits, avocados and sweet potato - to us, all delightful additions to our kitchens, but to the Aztecs, part of an extensive herbal medicine chest. But can you guess what they were used for? Many of those Aztec herbal medicines are still used, in more or less the same way, by their descendants in modern Mexico. But do any of them really work? How can we find out?

A branch of science called ethnopharmacology specialises in investigating the traditional medicines of the world. Ethnopharmacologists “live with indigenous people, to share the everyday life of their community and... respect the underlying cultures” (Heinrich, Barnes et al. 2004). From local healers, the scientists learn about the way herbal medicines are prepared and used. They can then take samples of the plants back to the lab to test their effectiveness. So, what do scientists say about the traditional Mexican herbal medicines? To find out, we can search through the scientific journals such as the Journal of Ethnopharmacology: it is in publications like these that scientists publicise their latest results and share them with others. This scientific literature shows that several research laboratories have a strong interest in traditional Mexican medicine.

16th Century medicine
Although most ethnopharmacological research at the moment focuses on those Mexican peoples still in existence, a few people have actually looked at the Aztec remedies as they were set down in the 16th century. In 2000, scientists at San Diego State University and Universidad Nacional Autónoma de México published a study of plants used in 16th century Mexican medicine, and concluded that the compounds present in those plants have “a broad spectrum of activities including…antibiotic, anti-inflammatory, cytotoxic” and several more (Bejar, Reyes-Chilpa et al. 2000). And back in the early 1980s, Davidson and Ortiz de Montellano tested the effectiveness of an Aztec wound remedy, as discussed in more detail by Professor Ortiz de Montellano himself, elsewhere on this site (follow links below).

And a plant well known to the Aztecs - iztauhyatl (Artemisia mexicana ssp. ludoviciana) is still widely used in Mexico for the treatment of infectious diseases. Navarro and colleagues, in 1992, checked whether this herb could inhibit the growth of disease-causing microorganisms. Their results showed that iztauhyatl, as well as a few other traditionally-used species, did indeed “possess strong in vitro antimicrobial activity” (Navarro, Villarreal et al. 1996).

In our own lab, too, some of our undergraduate pharmacy students have tested the effectiveness of traditional Aztec herbal medicines. Their mini-research projects have shown that extracts of ecapatli (Cassia occidentalis), cempoalxochitl (Tagetes patula) and yauhtli (Tagetes lucida) are effective against a range of bacteria. Although the results of these brief investigations are unpublished, their data shows potential for further investigation.

21st Century medicine
In the UK, Michael Heinrich and his group at the London School of Pharmacy have spent some years studying the plant-based medicine of modern indigenous Mexican people - including those descendants of the Aztecs, the Nahua, but also the Maya, Zapotec, Mixe and Popoluca (Heinrich, Ankli et al. 1998). They’ve made lists of the many plant species used by local healers, and classified those plants by their use. Heinrich’s group frequently use a mathematical formula which calculates “informant consensus factor”, which essentially describes, on a numerical scale ranging from 0 to 1, the degree to which the local healers agree on how the local medicinal plants should be used. This gives an idea of the potential effectiveness of the remedy - if there’s a lot of disagreement amongst the local people as to how effective a treatment is, you can bet that it isn’t really effective.

Research like Heinrich’s shows that the medicinal plants in Mexico are broadly categorised into three major areas: gastrointestinal complaints, like diarrhoea and dysentery; skin disorders (often caused by fungal infection), and respiratory disorders. You find this classification across pretty much all the Mexican populations. But there are other classes of use: the Nahua, for example, were found by Heinrich to use quite a few plants to soothe what researchers call “culture-bound syndromes”. A patient suffering from a culture-bound syndrome displays a collection of physical and psychological symptoms, but - crucially - only members of a certain culture would group those symptoms together and ascribe them to a single, culturally appropriate, cause.

The most well known culture-bound syndrome in Mexico today is called susto, or “fright sickness” - a condition that has its roots in the Aztec concept of tonalli. To the Aztecs, a sudden fright (as well as a few other things) might cause the tonalli - a type of soul - to leave the body.br
Interestingly, such culture-bound syndromes are not only the province of “indigenous” peoples, but affect modern city-dwellers too: eating disorders, leading in extreme cases to anorexia nervosa or obesity are, it has been argued, a form of Western culture- bound syndrome.

But let’s go back to the “big three” - gastrointestinal, skin, and respiratory disorders. What these three classes of illness have in common is that they are very frequently caused by bacterial or parasitological infection, and in fact most of the papers published in the last 15 years or so on the subject of Mexican ethnopharmacology focus on testing the antimicrobial action of traditional medicines. Hernandez and colleagues found that the plants used most often for gastrointestinal problems by the people of Zapotitlán de las Salinas were indeed effective against several pathogenic bacteria, with Lippia graveolens being the most effective (Hernández, Canales et al. 2003). And the chillazotl (Argemone mexicana) may even have the potential to treat malaria: the most serious parasitic disease in the world.

But Mexican herbs aren’t just used to treat infectious disease. Very recent research, only just published in the Journal of Ethnopharmacology, comes from a collaboration between French and Mexican scientists - Lautié and colleagues, based at the Universitié de Picardie Jules Verne in France, and Villarreal at the Universidad Autónoma Estado Morelos in Mexico. They have evidence that certain Mexican herbs could be useful in the treatment of cancer. They used a process called rationalised selection to select herbs traditionally used in Mexico for “cancer-related diseases”: those used for tumours, swellings and warts, amongst other symptoms. They then tested those plants for the presence of compounds known to be useful in the treatment of cancer. In two cases, they found those compounds, or compounds that were very similar. They also found that extracts of those two plants - Linum scabrellum and Hyptis suaveolens - were active against three different types of cancer cell cultures, which helps to validate the traditional use of those plants. (Lautié, Quintero et al.). Villarreal and her colleagues intend to continue their research.

Toxic plants?
Of course, the flipside of this research is that some plant extracts may be found to be harmful rather than helpful. In 2007, Déciga-Campos and colleagues published results of toxicity tests on 14 species frequently used in Mexico. They found that one species in particular, Poliomintha longiflora - one of a number of species that are colloquially called “Mexican oregano”, and used as a seasoning - showed “significant” toxicity in a number of tests, and they recommend that the “National Health Authorities notify local consumers as well as national and international traders about the risk of using this plant, at least until further studies are carried out.” (Déciga-Campos, Rivero-Cruz et al. 2007).

Medicinal guavas
And as for those guavas and passion fruits, avocados and sweet potatoes? How did they Aztecs use them? And do they really do anything other than taste good? Well, it depends what part of the plant you use. You can eat guava fruits, but the Aztecs used guava leaves to relieve cases of dysentery. And they used the roots of the passion fruit plant for snakebites; avocado oil as a hair conditioner, and sweet potatoes to cool the skin during a fever. Do they work? Well, scientists think the guava leaves certainly do (Caceres et al. 1990). But it’s important to remember that we can’t always be sure of the exact species that were used: there are lots of different types of passion fruit, for example. And sometimes plants can contain harmful chemicals. So, as they say: don’t try this at home!

As for the many other Mexican herbs used medicinally - well, several hundred years of continuous use suggests that they may have some effect. As long as we keep learning from the Mexican people, who knows what other medicines we may uncover?

References:-
• Andrade-Cetto, A. and M. Heinrich (2005). “Mexican plants with hypoglycaemic effect used in the treatment of diabetes.” Journal of Ethnopharmacology 99(3): 325-348.
• Bejar, E., R. Reyes-Chilpa, et al. (2000). Bioactive compounds from selected plants used in the XVI century mexican traditional medicine. Studies in Natural Products Chemistry, Elsevier. Volume 24, Part 5: 799-844.
• Caceres, A., O. Cano, et al. (1990). “Plants used in Guatemala for the treatment of gastrointestinal disorders. 1. Screening of 84 plants against enterobacteria.” Journal of Ethnopharmacology 30(1): 55-73.
• de Micheli-Serra, A. (2000). “Digitalic therapy. Historical outline.” Gaceta medica de Mexico 136(5): 511-518.
• de Sahagun, B. (1963). Fifth chapter, which telleth of the medicinal herbs and of the different herbs. Book 11: Earthly Things. 11.
• Déciga-Campos, M., I. Rivero-Cruz, et al. (2007). “Acute toxicity and mutagenic activity of Mexican plants used in traditional medicine.” Journal of Ethnopharmacology 110(2): 334-342.
• Diaz, J. (1976). Indice y sinonimia de las plantas medicinales de Mexico. Monografías científicas 1, IMEPLAM (Mexican Institute for the Study of Medicinal Plants).
• Diaz, J. (1977). Usos de las plantas medicinales de Mexico. Monografias Cientificas II, IMEPLAM (Mexican Institute for the Study of Medicinal Plants).
• Garcia Rivas, H. (2003). Plantas Curativas Mexicanas, Panorama
• Heinrich, M., A. Ankli, et al. (1998). “Medicinal Plants in Mexico: Healers’ Consensus and Cultural Importance.” Soc. Sci. Med. 47(11): 1859-1871.
• Heinrich, M., J. Barnes, et al. (2004). Fundamentals of Pharmacognosy and Phytotherapy, Churchill Livingstone.br
• Hernández, T., M. Canales, et al. (2003). “Ethnobotany and antibacterial activity of some plants used in traditional medicine of Zapotitlán de las Salinas, Puebla (México).” Journal of Ethnopharmacology 88(2-3): 181-188.
• Lautié, E., R. Quintero, et al. “Selection methodology with scoring system: application to Mexican plants producing podophyllotoxin related lignans.” Journal of Ethnopharmacology In Press, Accepted Manuscript.
• Loyoza, X. (1993). Two decades of Mexican ethnobotany and research in plant drugs. Ethnobotany and the search for new drugs, Fortaleza, Brazil, Wiley.
• Navarro, V., M. L. Villarreal, et al. (1996). “Antimicrobial evaluation of some plants used in Mexican traditional medicine for the treatment of infectious diseases.” Journal of Ethnopharmacology 53(3): 143-147.
• Ortiz de Montellano, B. R. (1990). Aztec Medicine, Health and Nutrition, Rutgers University Press.
• Yasunaka, K., F. Abe, et al. (2005). “Antibacterial activity of crude extracts from Mexican medicinal plants and purified coumarins and xanthones.” Journal of Ethnopharmacology 97(2): 293-299.

Picture sources:-
• Pix 5(L), 7 and 12: photos by Ian Mursell/Mexicolore
• Pix 1 and 9: photos by Maricela González/Mexicolore
• Pic 3 from the Florentine Codex scanned from our own copy of the Club Internacional del Libro 3-volume facsimile edition, Madrid, 1994
• Pix 4, 5(R) and 11: photos courtesy Corrinne Burns
• Pic 8 from the Codex Laud, scanned from our own copy of the ADEVA facsimile edition, Graz, Austria, 1966
• Pic 10: photo courtesy Michael Heinrich
• Other images from respective websites.

Professor Bernardo Ortiz de Montellano’s reference to Aztec wound remedies Aztec First Aid Learn more about the Badianus Manusript

Comments (1)

Tecpaocelotl

8th Mar 2009

I have a copy of the Badianus Manuscript & it’s a pretty good book. I have to explain to people that the letter (the intro) that they write, they write in a humble way. Even though it’s native medicine with european science (with good & bad blood). Once you understand what they’re trying to say, it makes more sense. The last link you recommend should actually be a guide to the book & makes it more easier to comprehend.

Mexicolore

We agree with Tecpaocelotl, who has posted some very helpful info on pre-Hispanic Mexican medicine on an ‘I’m Chicano’ forum: anyone interested should visit - http://www.soychicano.com/forums/showthread.php?t=10471

Corrine Burns, expert on Aztec herbal medicine