**Abstract**

The use of medicinal plants for the treatment of gastrointestinal disorders and ethnodiseases such as diarrhea, stomachache, dysentery, "empacho" (blockage), and bile is a common strategy among indigenous communities. It is estimated that approximately 34% of medicinal plants are used to treat diseases of the digestive tract. In Mexico, gastrointestinal infections caused by bacteria, parasites, or viruses represent one of the main causes of death in children in rural populations. Our objective was to document the use of medicinal plants used by the indigenous groups of Oaxaca, Mexico, for the treatment of gastrointestinal disorders, based on previous studies, experiences, and field observations in indigenous communities and supplemented with bibliographic references. In Oaxaca, there are 16 indigenous groups, the largest being the speakers of the Zapoteco, Mixteco, Mazateco, Mixe, Chinanteco, Amuzgo, Tacuate, Chatino, and Cuicateco languages. In this review of the medicinal plants used for gastrointestinal disorders, 186 species were grouped into 147 genera and 71 botanical families, among which the largest number of species belonged to Asteraceae (29), Fabaceae (15), Euphorbiaceae (9), Solanaceae (9), and Lamiaceae (9). Different pharmacological studies showed potential for preventing microbial and fungal pathogens that cause gastrointestinal disease.

**Keywords:** ethnodiseases, bioculture, indigenous knowledge, plant diversity

## **1. Introduction**

Medicinal plants are key elements of traditional medicine because they are part of the collection of knowledge and cultural heritage of sociocultural communities. Communities are often repositories and users of medicinal plants, and both rural and urban social groups with rural or indigenous origins have knowledge of these plants. Based on ethnobotanical, ethnomedicinal, and ethnopharmacological studies, the plants that are used by different healers and families of the Tarahumara, Yaqui, Chontal, Nahuatl, Mazahua, Otomi, Mixteco, Zapoteco, Mixe, Maya and Tzotzil groups, and all Mexican indigenous groups are symbolic [1].

In Mexico, gastrointestinal diseases are common in communities that are highly marginalized and poverty-stricken and are often transmitted through the fecal-oral route and the consumption of contaminated water and food. The infant population is the most vulnerable, both in terms of incidence and vulnerability [2]. In 2012, approximately 20% of the population of Chiapas, Guerrero, and Oaxaca did not have access to an adequate quality of water. This problem was exacerbated because only between 65 and 75% of houses have adequate waste management systems. Gastrointestinal diseases in children under 5 years of age directly affect mortality rates (19.2–19.4%) and mainly occur in marginalized communities [3]. These observations suggest that minimizing gastrointestinal diseases is dependent on the social environment of the community, access to clean water and food safety. As such, the symptoms and syndromes of diarrhea, stomachache, gastric atrophy, and enteric fever are associated with bacterial, fungal, parasitic, and rotavirus agents [2], and the frequency of these symptoms among children varies from community to community.

Medicinal plants are commonly used by communities for the treatment of gastrointestinal disorders through plant infusions, maceration, chewing, poultices, and different types of extracts (alcoholic or aqueous) [1]. Some studies have documented the traditional uses of medicinal plants by healers, their conservation, and their cultural importance in different indigenous groups [4–9]. Other studies have contributed ethnobotanical knowledge of medicinal plants [10–12]. The evaluation of phytochemical compounds with medicinal activity is also a subject of interest [13–16]. One aspect in which different authors have devoted a great amount of attention to is the antiparasitic and antimicrobial effects of medicinal plants for the treatment of diarrhea and other gastrointestinal disorders [17–25].

 Research in natural products is often based on ethnobotanical information. One goal of ethnopharmacology is to improve the understanding of the pharmacological effects of plants on health, especially for indigenous communities that are highly marginalized and poverty-stricken. In this study, we examined plants used for the treatment of gastrointestinal disorders such as diarrhea, dysentery, and abdominal pain. The objective of this work was to document the use of medicinal plants used by the indigenous groups of Oaxaca, Mexico for the treatment of gastrointestinal disorders, based on previous unreported studies, experiences, and field observations in indigenous communities. Our results are supplemented with bibliographic reviews.

### **2. Sociocultural and ethnographic context of Oaxaca, Mexico**

Mexico has an indigenous population of 12.25 million (10.1% of the total), of which 7.38 million speak an indigenous language [26]. It is estimated that there are 1.2 million speakers in Oaxaca over 3 years of age that speak an indigenous language. Oaxaca is the state with the largest indigenous population (32.2% of its total population) and has 245 municipalities where more than 40% of the population speaks indigenous languages [26–28]. However, in Mexico, 24.4 million people consider themselves indigenous [26, 29], a figure that is higher than the total number of inhabitants of several European countries and is of great importance in the preservation of culture, biodiversity, and biocultural heritage. Indigenous peoples are also associated with the use of medicinal plants.

Based on the vegetation, ecosystem, biome, and indigenous settlement maps, Toledo et al*.* [30] identified 26 indigenous regions in Mexico. These regions coincide with the zones of greatest biodiversity and pluriculturality or indigenous settlements and are also where protected natural areas are located. In Oaxaca, eight

indigenous regions were identified: Mixteca, Cañada, Papaloapan, Sierra Norte, Istmo, Costa, Sierra Sur, and Valles Centrales Different indigenous communities can be found in each of these regions. The Mixteca region is dominated by the Mixteco, Triqui, Chocho and Nahuatl groups, the Cañada by the Cuicateco and Mazateco groups, and so on. The topography of the mountainous areas and valleys of Oaxaca is rugged, with contrasting climates ranging from humid temperate at 2000–3000 masl, to temperate to subtemperate in intermediate zones from 1000 to 2000 masl, to tropical and subtropical regions (<1000 masl) [31]. Thus, indigenous communities are located in various climates, altitudes and vegetation, and consequently have access to and knowledge of different medicinal plants. We should note that among Oaxaca indigenous regions, the differences are not extreme in terms of climatic conditions, flora, fauna, topography, crops, handicrafts, and the use of traditional medicinal plants (**Table 1**); however, there are sociocultural differences in the knowledge associated with the use of plants for treating ethnodiseases and diseases with clinical diagnoses.

Among indigenous communities from distant ethnic regions and origins, and occupying different geographical territories, the use of plants for the treatment of gastrointestinal disorders is different, even though the symbolic or cosmological meanings may be the same. Thus, there is similar understanding of how plants are


#### **Table 1.**

*Ecogeographic descriptions of eight indigenous regions of Oaxaca, Mexico.* 

#### *Pharmacognosy - Medicinal Plants*

used to treat stomach, intestinal, diarrhea, or psychosomatic diseases (e.g., "susto" (fright), stomachaches, "mal aire" (bad air) with vomiting, and "empacho" (blockage), but the species of plant used, form of use, and application differ significantly between ethnic groups. In severe cases of illness, indigenous peoples resort to the community healers or alternate among medical professionals, pharmaceutical medicine, and the use of medicinal plants recommended by the family or healers [32, 33].
