Background

Cultural mixing mediated by the migration of people around the world has generated increasing interest in recent years within the field of ethnopharmacology [1]. Medicinal plants have been used by human societies throughout history, also across geographical barriers [2]. The continuous use of certain plants and animals for medicinal purposes over time reflects their potential therapeutic value. Such substances become even more promising when they are persistently used by migrating human groups despite the considerable distances travelled and the consequent exposure to different cultures and vegetal resources. Numerous studies have collected information on medicinal plants from ethnic groups who migrated from Mexico to the U.S.A. [3, 4]; from Haiti to Cuba [5]; from Africa to South America [6]; from Africa to Brazil [7]; from Colombia to London [8]; from Suriname to the Netherlands [9]; from Albania to southern Italy [10, 11]; from Germany to eastern Italy [12]; and from Europe and Africa to eastern Cuba [1, 13]. However, few studies have focused on migration within a country, such as that described by Rodrigues et al. [14] regarding migrants from northeastern Brazil who currently occupy the southeast.

Brazil offers a favourable environment for studies focused on migration and medicinal plants/animals because it possesses a large area of 8,514,876.599 km2 [15] and boasts high indices of cultural and biological diversity. Brazil is inhabited by rural and urban populations of 232 indigenous ethnic groups [16], 1,342 Quilombola groups (descendants of Afro-Brazilian people) [17], and mestizo groups derived from the miscegenation of Indian, Black, European and Asiatic people. Brazil also houses 55,000 species of higher plants [18] and almost 7% of global animal diversity was described (ca. 100,000 out of 1.5 million), though some estimates suggest that this number is significantly higher [19]. Migration between regions of this country encourages contact with the rich biological and cultural diversity and allows interpersonal interactions that contribute to the transformation of local medicinal therapies.

According to Simões and Lino [20], the original Atlantic Forest covered approximately 1.3 million km2, spanning 17 Brazilian states from south to northeast; however, it currently covers only 14 states, and its area has been reduced to 65,000 km2. Despite considerable fragmentation, the Atlantic Forest still contains more than 20,000 plant species (8,000 endemic) and 1,361 animal species (567 endemic). It is the richest forest in the world in wood plants per unit area; the southern Bahia, for example, holds a record of 454 different species/ha [21].

The objective of this study was to perform an ethnopharmacological survey among migrants from northeastern and southeastern Brazil who currently live in Atlantic Forest remnants in the municipality of Diadema (São Paulo state, southeastern Brazil). We attempted to understand how the medicinal use of certain plant and animal changed as a result of the migrants' contact with new therapies, diseases and natural resources found in Diadema. These findings were classified as either: maintenance, replacement, incorporation or discontinuation of plants/animals use.

These objectives are in agreement with several stated goals of ethnopharmacology, namely, to investigate how migration can influence knowledge of medicinal plants/animals, the extent to which displaced people incorporate new species into their therapeutic methods, and, in particular, why individuals sometimes persistently adhere to old customs, before or even after they are exposed to new possibilities. Therefore, we adopt the hypothesis that the use of plants/animals as medicines is influenced by migratory movements, and access to natural resources available in the municipality of Diadema.

Methodology

Fieldwork

One of the authors (D. Garcia) spent 14 months (September 2007 to November 2008) in the municipality of Diadema, São Paulo, SP, Brazil (23°41'10"S, 46°37'22"W) (Figure 1), selecting, observing and interviewing migrants living in the Atlantic Forest remnants. Diadema is located 16 kilometres from the capital São Paulo, covers an area of 30.65 km2, and is occupied by 394.266 inhabitants [15], most of whom are migrants from other regions of Brazil. The municipality has a literacy rate of 6.8% [22], and its Human Development Index is 0.79 [23]. The Atlantic Forest remnants found in this city are rich in plants that are either native or introduced by the influence of those migrants present both in urban and rural areas.

Figure 1
figure 1

Location of the Municipality of Diadema, in São Paulo state, southeastern Brazil (black square). Interviewees' migration from their cities of origin to Diadema, being PE (Pernambuco state), SE (Sergipe), MG (Minas Gerais) and SP (São Paulo), and the distance of the displacement in each case (in Km).

Migrants who had relevant knowledge regarding the use of plants and animals for medicinal purposes were selected for interviews following the purposive sampling method [24]. Thus, we sought information about the presence of migrants from herb traders, health care professionals, and some local prayer-makers. According to Bernard [24], this sampling is also known as judgment sampling, utilized during qualitative research in particular in those populations that are difficult to be localized, the researcher selects interviewees based on their trial that they meet the criteria for the study of the phenomenon of interest. After identifying potential interviewees, the researcher visited them to determine whether they did indeed possess knowledge on medicinal plants and whether they wanted to take part in this study. The ethnopharmacological study was approved by the Ethics Committee of Universidade Federal de São Paulo (UNIFESP's Ethics Committee on Research 1969/07) and Conselho de Gestão do Patrimônio Genético (No. 02000.001 049/2008-71). The interviewees also signed consent forms granting permission to access their knowledge and collect botanical and zoological material.

Personal and ethnopharmacological data from the interviewees were obtained through informal and semi-structured interviews [24] that addressed the following topics: personal details and migration history (name, sex, age, religion, marital status, place of birth, migration, main occupation, grade of schooling) as well as ethnopharmacology (name of natural resource, use, part used, formula, route of administration, contraindications, dosages, restrictions of use). The author (D. Garcia) has visited each interviewee at least 12 times, in order to fill in the forms mentioned above, as well as to understand their processes of acquiring knowledge in depth.

Each medicinal plant was collected in the presence of the person who described it during the interviews, in accordance with the methods suggested by Lipp [25]. The plants' scientific names were determined by specialists from the Instituto de Botânica do Estado de São Paulo (IB), and vouchers were deposited at the Herbário Municipal de São Paulo (PMSP). The animals collected were placed in glass vials containing 70% ethyl alcohol, and their subsequent identification and deposit were performed by zoologists from the Museum of Zoology, Universidade de São Paulo (MZUSP) and the Bioscience Institute from Universidade de São Paulo (IB-USP).

When interviewees cited plants and animals that were used only in their cities of origin, i.e., not available in Diadema, photos from the literature and other information (e.g., popular name, habits and habitat) were used to identify them to at least the genus level. These organisms are marked with asterisks throughout the text and in Table 1. The Herpetofauna of the Northeast Atlantic Forest [26] and The Herpetofauna of Caatingas and Altitudes Areas of the Brazilian Northeast [27] were used as identification guides. For plants, we also consulted Medicinal Plants in Brazil - Native and Exotic [28].

Table 1 The 12 animals indicated by migrant PE2, their popular and scientific names, complaints (part used), formula and route of administration.

Database survey

For the plants and animals identified to the species level, we searched the bibliographic databases PUBMED [29] and SCIFINDER [30] to determine whether they had been targets of previous pharmacological studies. To determine the origin of each plant species, we consulted the Dictionary of Useful Plants: exotic and native [31].

Dynamics of use

During our field work, we made an effort to understand the dynamics of use for each resource and classified them into the following four categories: maintenance of use (resource used for the same purpose in the migrant's city of origin and in Diadema), replacement (resources that were replaced when migrants arrived in Diadema because the original product was not available in Diadema or was less effective than the new resource), incorporation (resources used for the first time in Diadema to treat diseases common to larger cities, such as hypertension, diabetes and anxiety, which were not common in their homeland), and finally discontinued use (resources that are no longer used in Diadema, usually because they are not available).

Data analysis

The level of homogeneity between plant information provided by different migrants was calculated using the Informants' Consensus Factor, Fic [32]. This term is calculated as Fic = Nur - Nt /(Nur - 1), where Nur is the number of use reports from informants for a particular plant-usage category and Nt is the number of taxa or species used for that plant usage category across all informants. Values range between 0 and 1, with 1 indicating the highest level of informant consent. For instance, if certain taxa are consistently used by informants, then a high degree of consensus is reached and medicinal traditions are viewed as well-defined [33].

Results and Discussion

Migrant Interviews

Despite the fact that Diadema is composed by thousands of migrants, we observed that only a few have retained traditional knowledge pertaining to medicinal plants and animals. Some considerations should be made, in order to justify our decision of conducing a qualitative approach, in depth, with the sample of interviewees obtained during the two months prior to the start of the study. During this time we observed that in many cases, this knowledge has fallen into disuse because of: a) a cultural adaptation to the new city, b) the ease of conventional medical care, c) forest degradation, which restricts use of local plants and animals, furthermore d) many migrants have shown concern to participate in the study, since in the past they suffered persecution from government agencies and physicians, who eventually restrained their medical practice.

The five selected interviewees migrated from northeast and southeast Brazil and established themselves in Diadema in the 1940 s. Three were born in the northeast: two in Pernambuco state (coded as PE1 and PE2) and one in Sergipe state (SE1). The two remaining migrants were born in the southeast: one in Minas Gerais state (MG1) and one in inland São Paulo state (SP1) (Figure 1). All interviewees were Catholic, married and retired, with the exception of PE1 and PE2 who sell medicinal plants. Their average age was approximately 68 years old (ranging from 53 to 80 years old), and their level of education was semi-illiterate to illiterate. They learned about the medicinal uses of plants and animals from their parents and grandparents (Brazilian natives, European and African descendants) in their homelands. All interviewees arrived in the city of Diadema as adults, and some had migrated through different regions of Brazil, accumulating knowledge on natural resources from human and biological sources. In Diadema, they acquired knowledge from neighbours, books, media (radio, television, magazines), and personal experiences.

Plants: dynamics of use

The migrants described their knowledge of 85 plant specimens. As can be seen in Table 2, 78 of them were available in Diadema and were collected, resulting in 65 plant species, the remaining 13 could only be identified to the generic level. The plants belong to 37 taxonomic families, with Asteraceae (16 species), Lamiaceae (8) and Euphorbiaceae (7) as the most common. Previous studies have shown that Asteraceae species are the group most commonly reported to have potential pharmacological properties, not only in the Atlantic Forest [3436] but also in other Brazilian biomes such as the Amazon Forest [37] the pantanal wetlands [38] and the cerrado savannahs [39]. In a review focusing on plants with possible action/effects on the central nervous system that were indicated by 26 Brazilian indigenous peoples occupying different Brazilian biomes [14], Asteraceae was the second most commonly cited family. The same pattern has been detected in other countries, such as Mexico [40]. One factor that may explain the common use of this taxonomic family is the large number of species belonging to it - about 20,000 [41]. Asteraceae also has a wide geographical distribution, both in Brazil and throughout the world [42], which facilitates its use by various cultures.

Table 2 The 78 plant specimens used by five Diadema's migrants (MG1, SP1, PE1, PE2, SE1)*.

From the 65 species identified, it was observed that 33 are native to Brazil while the other 32 are exotic, demonstrating the great floral diversity of the region, which was influenced by European and African people during the civilizing process in Brazil. Furthermore, of the 78 specimens recorded, 54% (42) are spontaneous or were already available in Diadema when interviewees arrived there, while 46% (36) were grown by the migrants, acquired in free markets, or brought from other regions of the country during migration. Below, we describe the four 'dynamics of use' categories observed during this study.

Maintenance of use

According to the interviewees, 68 of the 78 specimens cited in the present study, were used in their homelands (highlighted with □ in Table 2). The maintenance of their uses was possible since most of them were available in Diadema, though some were brought from their homelands. SE1 brought four plants from Aquidabã - Sergipe state, for pain relief because they are not available or are more potent than the ones found in Diadema: "bálsamo" (Sedum sp.), "anador" (Alternanthera sp.), "eucalipto/vick" (Eucalyptus globulus Labill.) and "novalgina" (Achillea millefolium L.).

Incorporation of use

Fourteen of the 78 specimens listed in Table 2 came to be used by migrants when they arrived in Diadema (highlighted with Δ in Table 2). These incorporations occurred in several ways: through information given by neighbours; through local media, e.g., television, radio, magazines; or through personal efforts, guided by plant organoleptic properties or even by the theory of signatures. This theory, formulated by Paracelsus (XVI century), assumes that characteristics and virtues of herbs can be recognised by their external appearance or "signature" (picture, shape, colour). Finally, observing the relationship between animals and plants can be a valuable guide. PE1 noted that dogs consume "sete-sangria" (Cuphea carthagenensis (Jacq.) J. F. Macbr.) when they have diarrhoea; and because it seemed to alleviate their symptoms, he started to use this plant for the same purpose.

The migrants incorporated several plants after their arrival in Diadema to treat typical diseases of larger cities: "cipó-cruz" (Serjania sp.) to combat high cholesterol; and "guanxuma" (Sida rhombifolia L.) and "guiné" (Petiveria alliaceae L.) for anxiety. Also included in this category was knowledge concerning local toxic plants, e.g., alamanda-amarela (Allamanda cathartica L.) and azaléia (Rhododendron simsii Planch.), detailing the risks associated with their consumption.

Replacement of use

Three plants used by migrants in their cities of origin were replaced because they were not available or were less effective than plants present in Diadema (highlighted with # in Table 2). Most of these replacements were made according to the criteria listed in the previous section.

The interviewee MG1 explained that in his homelands, he used "quebra-pedra"* (Phyllanthus cf. caroliniensis Walter - Euphorbiaceae) for kidney stone disturbance, but when he arrived in Diadema, he found another plant, "sofre-do-rim-quem-qué" (Cissus sp.), that seemed to have a stronger effect.

Another interviewee, PE1, reported that the bark and seeds of "amburana-de-cheiro"* (Amburana cf. cearensis (Allemão) A.C. Sm. - Fabaceae s.l.) were widely used for anti-inflammatory therapy in Pernambuco state but had to be replaced by "mentruz" (Chenopodium ambrosioides L.) because the former was not found in Diadema. In addition, SE1 had to replace "pau-de-sapo"* (Pouteria cf. melinoniana Boehni - Sapotaceae), whose leaves were used for chronic wounds, with "carrapicho" (Acanthospermum australe (Loefl.) Kuntze).

The vernacular names of some plants are registered trademarks of allopathic medicines and active ingredients, e.g., Novalgina® (Achillea millefolium) and Vick® (Eucalyptus globulus) for sinusitis, and Anador® (Alternanthera sp.), which is used as a sedative and for general pain. Contact between migrants and allopathic medicine thus led to the 'baptisms' of these plants, following the observation that both, the commercially available products and herbal source have similar effects, as reported by Pires [43].

Discontinued use

According to MG1, the following plants used in his homeland fell into disuse because they were not found in Diadema, although he tried to acquire them from local commercial sources: "quina"* (Strychnos cf. pseudoquina A. St. Hil - Loganiaceae), whose root is used to combat pain in the stomach and intestine; bark oil of "jatobá"* (Hymenaea cf. courbaril L. - Fabaceae s.l.), used for combat wounds; "batata-de-purga"* (Operculina cf. macrocarpa (L.) Urb - Convolvulaceae), whose tuber is ingested as a purgative and to clean the blood; bark and leaf of "jalapa"* (Mirabilis cf jalapa L. - Nyctaginaceae), used to clean the blood; tea of "junco"* (Cyperus cf. esculentus L. - Cyperaceae), whose root is used for inflammation; bark or seed of "emburana"* (Amburana cf. cearensis - Fabaceae s.l.), used for migraine and sleeping; and bark of "angico"* (Anadenanthera cf. colubrina (Vell.) Brenan - Fabaceae s.l.), prepared as a tea for pain in the body and fever. These plants were not described in Table 2, since they could not be collected and identified as well.

Plants used for therapeutic purposes

Of the 78 plants, 10 carry some restrictions, as they can be toxic depending on the dose, route or part utilised (Table 2). The uses described in Table 2 are written just as they were reported by the interviewees. The 68 plants used exclusively for medicinal purposes were cited for 41 complaints, which were grouped into 12 functional categories according to bodily system, as detailed in Table 3. Thus, gastrointestinal disturbances include the following complaints (numbers of medicinal plants reported): endoparasitosis (1), ulcer (1), diarrhoea (1), bellyache (2), heartburn (1), intestinal infections (1), liver pain (3). This category also includes plants used to improve digestion (1), to treat tables of haemorrhoid (1), as laxatives (10) and to purify the stomach (2), comprising a total of 24 plants employed in 44 formulas.

Table 3 The 12 categories of use comprising the 41 complaints, their total and partial number of plants cited by the five migrants.

The most relevant categories of use, measured by number of species employed, were gastrointestinal disturbances (30.8% of plants), inflammatory processes (24.4%) and respiratory problems (23.1%). As seen in Table 4, the group of illnesses representing immunological problems obtained the highest informant consensus factor value (Fic = 0.66), while the other categories presented Fic values lower than 0.5. These low values reflect the diversity of knowledge displayed by migrants, which can probably be attributed to different cultural influences during their migrations through Brazilian territory. Furthermore, the small number of interviewees may have resulted in low values of Fic.

Table 4 Values of Informant consensus factor (Fic) for each category of use, considering the plants cited by the five Diadema's migrants.

The parts of the plants most often used in the formulas were leaves (45.4%) and other aerial parts (22.7%). The most common formula was the infusion (37.8%), followed by in natura (17.6%) and syrup (10.1%). The most cited route of administration was ingestion (51.3%), followed by inhalation (8.4%) and topical (3.4%).

Plants with restrictions on use and/or toxic

Among the 10 specimens with restrictions on use, 6 were designated as only toxic: "alamanda-amarela" (Allamanda cathartica), "algodão-do-mato" (Asclepias curassavica L.), "amendoim-bravo/burra-leiteira" (Euphorbia heterophylla L.), "azaléa" (Rhododendron simsii), "comigo-ninguém-pode" (Dieffenbachia sp.) and "impatiens" (Impatiens hawkeri). The interviewees explained that depending on the dose, the latex of "alamanda-amarela" and "amendoim-bravo" can cause discomfort or even blindness. According to Oliveira et al. [44], the leaves of Dieffenbachia picta Schott contain calcium oxalate, which damages the oral mucosa and provokes pain and oedema, while the leaves of Allamanda cathartica contain cardiotonic glycosides and induce intense gastrointestinal disturbances.

Although reported as toxic, the latex of two other plants can be used at low doses to treat breast and stomach cancer: "avelóz" (Euphorbia tirucalli L.) and "jarnaúba" (Synadenium grantii Hook. F.), respectively. The sap of "embaúba" (Cecropia pachystachya Tréc.) was indicated as toxic, but its fruits are used to combat bronchitis. Finally, the seeds of "pucunã" (Fevillea passiflora Vell.) are toxic, being indicated as abortive. In a recent study, Rodrigues [45] also described plants with restrictions of use as reported by three Brazilian cultures: the Krahô Indians use two plants as abortives in a single prescription: "aprytytti" (Acosmium dasycarpum (Vogel) Yakovlev) and "ahkryt" (Anacardium occidentale L.) (Anacardiaceae); their barks are boiled, and the beverage is ingested in at dawn. It is an extremely bitter beverage, rich in tannin and therefore extremely astringent.

Pharmacological data

As can be seen in Table 2, 57 species (73.1%) were featured in previous pharmacological studies. For 30 of these species (52.6%), the uses cited by the migrants showed some similarity to the investigated effects/actions, demonstrating concordance between popular knowledge and academic science (marked with an asterisk in Table 2).

Table 5 The 6 categories of use comprising the 9 complaints, their respective number of animals mentioned by the migrant PE2.

Animals used for therapeutic purposes and dynamics of use

From the five interviewees, only one (PE2) offered knowledge on the medicinal uses of 12 animals. They belong to four taxonomic classes: Reptilia (6 species), Insects (3), Mammalia (2) and Amphibia (1). However, the interviewee has used only two animals since he arrived in Diadema, the other ten animals fell into disuse because they are not available in this city. The two animals were collected, identified and deposited in the Museum of Zoology-USP: ant (Atta sexdens L.) and cockroach (Periplaneta americana L.). These species belong to the maintenance of use category (highlighted with □ in Table 1). The other ten species therefore belong to the discontinued use category (highlighted with Ο in Table 1) which could not be collected. Their identifications were made by PE2 through consulting images from books (as described in Methodology). For three animals (snake, alligator and giant water bug) PE2 could only hesitantly confirm their identity, probably due to the great diversity of these animals in Brazil. Therefore, they are denoted in Table 1 as probably belonging to one of three possible genera.

The animals were used in 14 different medicinal formulas, with the skin most commonly used (33.3%), followed by whole animal (20.0%), bone (13.4%), fat (6.7%), rattle (6.7%), tooth (6.7%), anthill (6.7%) and turtleshell (6.7%). Some studies conducted in Brazil show that concomitant data corroborate and sustain these uses [4650]. The formulas were cited for the treatment of nine complaints, which were grouped into six functional categories, as shown in Table 5. The most commonly cited formula was powder (66.7%), followed by in natura (20%). The most frequent route of administration was ingestion (78.6%).

The most common complaint involved respiratory problems (58.4%; 7 animals) followed by central nervous system (8.3%), inflammatory processes (8.3%), dermatological problems (8.3%), analgesics (8.3%), cardiovascular problems (8.3%) as shown in Table 5. The high humidity of the region (with annual rainfall between 1.000 and 1750 mm) [21] is known to lead to bronchitis, cough and asthma. This may explain why so many plants and animals were used to treat respiratory disturbances in Diadema, which has been shown in studies of the Sistema Único de Saúde [51] to be the second largest cause of death in Diadema - 14,4%.

Many animals have been used for medical purposes since antiquity [5255]. Despite the existence of several ethnopharmacological studies suggesting the bioactive potential of Brazilian fauna [37, 5661], only marine animals have been investigated by chemical and pharmacological methods [6264]. No pharmacological data was found in the literature for the five animals identified in the present study: rattlesnake (Crotalus cf. durissus L.), capybara (Hydrochoerus cf. hydrochaeris L.), iguana (Iguana cf. iguana L.), ant (Atta sexdens) and cockroach (Periplaneta americana). The lack of information available on medicinal animal products leads us to conclude that this is a largely unexplored topic in Brazil and that future pharmacological studies should confirm the potential therapeutic value of these species.

Conclusion

The migrant interviewees demonstrated knowledge about the medicinal and toxic properties of plants and animals available in the Atlantic Forest remnants of the municipality of Diadema. Migration contributed to the expansion of knowledge regarding the use of natural resources, especially through the processes of resource replacement and/or incorporation. Moreover, the maintenance of original uses of certain resources demonstrates their value in the migrants' therapeutic practices.

The seven plants [Impatiens hawkeri W. Bull., Artemisia canphorata Vill., Equisetum arvensis L., Senna pendula (Humb. & Bonpl. ex Willd.) H.S. Irwin & Barneby, Zea mays L., Fevillea passiflora Vell. and Croton fuscescens Spreng)] and the two animals (Atta sexdens and Periplaneta americana) that showed maintenance of use among migrants during their displacement in Brazilian territory, have not been studied by pharmacologists yet. These species should be highlighted in further investigations because the maintenance of use during human migrations can be indicative of bioactive potential.

This work also demonstrates the impossibility of sharing benefits related to property rights with cultures under certain circumstances, as the dynamic use of natural resources presents particularly varied influences. The interviewed migrants had passed through several Brazilian cities and were exposed to distinct vegetation and cultures. In this migration, they have passed on and incorporated knowledge in an intensive exchange where formulas and uses are mixed and re-invented as a result of contact between cultures.