Ethnopharmacological studies in 21st century Brazil: a systematic review

Brazil is a country with a large party of the population, including traditional communities, that use plants for medicinal purposes, however, the prospect of drugs derived from plants is still little explored. The present study aimed to carry out a systematic review of the literature, in an attempt to understand how studies involving ethnopharmacology have developed in Brazil during the 21st century. The Scielo and PubMed data bases were used, using the keywords “ethnopharmacology” and “Brazil”. In a total of 212 articles were selected and the highest number of publications in the years of, respectively: 2018 (9.43%), 2020 (8.96%) and 2014 (8.96%). Experimental studies (laboratory studies, such as phytochemicals and biological activity) accounted 41.98% of the total, followed by literature reviews (36.32%) and ethno-directed interviews (20.28%). The results showed that the most common types of studies were popular use and biological activity (33.96%), followed by studies of popular use, phytochemical composition and biological activity (21.70%) and ethno-directed survey (20.75%). The most cited botanical families were Fabaceae (8.49%), Asteraceae (5.19%) and Lamiaceae (2.83%) and the main biological activities evaluated were anti-inflammatory (10.85%), antimicrobial (10 .85%), antimalarial (5.19%) and antioxidant (4.72%). Among the traditional communities surveyed were rural communities (50%) and quilombola communities (13.64%). The present study indicates that there was a significant increase in publications involving ethnopharmacology in Brazil, mainly from 2010, associated with a greater diversification of the researched objectives.


Introduction
Since antiquity, humans have used plants for medicinal purposes, this being the main practice for fighting diseases and restoring health until the mid-20th century (Barbosa et al., 2012;Cardoso et al., 2017;Sales et al., 2015). From the improvement of techniques for the synthesis of chemical compounds, developed by the pharmaceutical industries at a more accentuated level from the 1940s onwards, synthetic substances started to occupy most of the international medicine market, due, among several factors, to the possibility large-scale production and greater control of composition and dosage (Pinto et al., 2002;Fernandes, 2004;Viegas Jr. et al., 2006).
Despite this, it is assumed that approximately 25% of all drug prescriptions are still formulations based on substances derived from plants, synthetic analogues or their derivatives and that the use of plants for medicinal purposes has a much higher percentage expressiveness in developing countries, in rural areas and in traditional communities (Newman & Cragg, 2007). This, due to the sociocultural background, as well as the precariousness of conventional medical care, which makes traditional medicine the only resource available to most of these populations (Cavaglier & Messeder, 2014;Sales et al., 2015).
In this context, Brazil represents one of the countries with the greatest biodiversity in the world, with 49,979 native, cultivated and naturalized species (Flora do Brasil, 2020), thus having an immense potential, as yet unexplored, for the prospecting of plant-derived drugs. The prospection of bioactive plant compounds of pharmaceutical interest has taken place through different analytical methods, among which the random, ethological, chemotaxonomic or phylogenetic approaches and the ethno-directed approach stand out (Albuquerque & Hanazaki, 2006). The latter consists of the selection of species according to the indication of specific population groups, usually, but not only, traditional communities, using the application of their empirical knowledge in their health and disease systems as substrate for the expansion of scientific knowledge. This type of approach has shown expressive results how in the study conducted at Sinai (Egypt) for plants with antimicrobial activity, 83.3% of the species obtained positive results by the ethnoguided approach against 41.7% in the randomized approach (Barbosa et al., 2012).
According to the National Commission for the Sustainable Development of Traditional Communities of the Ministry of Social Development of Brazil, traditional peoples and communities are defined as: "culturally differentiated groups that recognize themselves as such, who possess their own forms of social organization, which occupy and use territories and natural resources as a condition for their cultural, social, religious, ancestral and economic reproduction, using knowledge, innovations and practices generated and transmitted by tradition" (Brasil, 2007). This definition includes indigenous peoples, "quilombola", peoples of African origin or "terreiros", romani people, riverside people or "ribeirinhos", artisanal fishermen, extractive communities in general, "geraizeiros", among others (Brasil, 2007).
Many of these traditional communities, mainly in developing countries, still make extensive use of plants for medicinal purposes (Arruda et al., 2019). The sustainable management of biological resources for the development of drugs, if carried out together with the maintenance of traditional knowledge and practices, respect and sociocultural valuation and with effective economic return to these communities, can help to resolve the dichotomy "economic development" versus " environmental preservation", so on the agenda nowadays, especially with regard to the Amazon biome (Ministry of the Environment, 2000).
It must be considered that, in the sociocultural and religious context of these communities, health promotion takes place through a holistic perception, in the mental, physical and spiritual dimensions, generally seen in an inseparable way (Brazil, 2018;Paz et al., 2015;Arruda et al., 2019). In addition to the cultural envelope, the strong empirical experience of these communities is extremely valuable for the construction of academic and scientific knowledge, however, extremely difficult without understanding the first one. As emphasized by Sales et al. (2015), the main purpose of ethnopharmacology is to understand the interrelationships between traditional communities and their use of medicinal plants and, for this to occur, it is necessary to fully understand the concepts of the sociocultural system from which the information is obtained, since noncontextualized observations are scientifically useless.
In this context, transferring knowledge from a specific cultural language to the scientific language without a good understanding of the two languages is an extremely difficult task and prone to several interpretative errors. An initial sociocultural immersion is necessary to enable the understanding of the information received, so that these data can be correctly translated into scientific language. Thus, understanding the sociocultural aspects and cultural identity of the traditional communities under study is extremely important (Sales et al. 2015;Silva et al. 2021).
With the advance in the knowledge of the bioactivity of plant secondary metabolites, there was an increase in both ethno-directed surveys and ethnobotanical studies to identify plants used for therapeutic purposes, mainly those used by traditional communities, as well as in the number of studies on the phytochemical composition and biological activity of the substances present in the various plant species (Pagnocca & Hanasaki, 2020 Agency (ANVISA), which provides for the registration of herbal medicines, created an even more favorable environment for ethnopharmacological research in Brazil, by providing clear guidelines for the manufacture of herbal medicines and for their inclusion in pharmaceutical assistance within the Unified Health System (SUS) (Sales et al., 2015).
In an attempt to understand how studies involving ethnopharmacology have been developed during the present century in Brazil, due to the PNPMF and resolutions of the National Health Surveillance Agency (ANVISA), the advance in knowledge of the bioactivity of vegetable secondary metabolites and the greater popularization of equipment and research techniques, the aim was to carry out a systematic review of the literature, by prospecting scientific articles in specific databases.

Methodology
The systematic review of literature was carried out in databases such as Scielo and PubMed, using the keywords  In order to identify how ethno-directed research has been developed within the national reality in recent years and whether it is possible to correlate the development of specific public policies with the quantity and profile of academic research related to them, were defined as inclusion criteria: articles that described an ethnopharmacological survey, chemical composition tests, biological activity tests or toxicity tests and studies with the association of one or more of these objectives, related to medicinal plants used by traditional communities, carried out by researchers from Brazilian institutions or those in partnership with researchers from foreign institutions, written in English or Portuguese. As exclusion criteria, we used publications that did not address the chosen topics, publications duplicated by the search system or keywords used for the research that appeared only in the discussion of the article, without presenting great relevance and contextualization of the topic.
The articles that met the inclusion criteria were tabulated for descriptive statistical analysis, performed using the Stata® software (Sousa and Silva, 2000). In order to better understand the results and establish a method for performing the descriptive statistical analysis, the selected articles were separated into groups that showed differences between the variables, such as: types of study (literature review, field interviews, experimental studies in the laboratory, comparative study between ethno-directed and random collection method) and purpose or objective of the study (identification of the phytochemical composition, verification of biological activity in vitro or in vivo, toxicity verification, survey of popular use through semistructured interviews, among others).

Profile of selected articles and quantitative by year of publication
Were found 237 articles, of which 212 were relevant to the inclusion and exclusion criteria. Of the works analyzed, 91.04% were developed by researchers in national institutions and 8.96% by Brazilian researchers in partnership with foreign institutions (Figure 2). No foreign researches were found in national territory without partnerships with researchers or national institutions, probably due to the restriction of access via authorizations to the genetic heritage and associated traditional knowledge and remittance abroad, for the cases referred to in art. 13 of Law No. 13,123 of 2015(Brazil, 2016.

Figure 2. Number of articles that met the inclusion and exclusion criteria (y axis) versus year of publication (x axis).
Source: Authors.
Considering the year of publication/percentage of articles published ratio, those with the highest publication were: 2018 (9.43%), 2020 (8.96%) and 2014 (8.96%), with a significant increase in publication of articles with an ethnopharmacological focus in the second decade of the 21st century ( Figure 2). This substantial growth may be associated, among other factors, with the publication of the PNPMF and ANVISA's resolutions, in order to regulate and support the criteria for releasing the commercialization of herbal medicines, as one of the main guidelines of this policy is precisely to promote the encouragement of research and development of medicinal and herbal plants, prioritizing the country's biodiversity (Brazil, 2006). Research, Society andDevelopment, v. 11, n. 2, e48211225956, 2022 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v11i2.25956 6 To analyze the "type of study" published, publications were categorized into different groups, such as: literature review, laboratory experimental studies, field research with ethno-directed interviews, among others, according the Table 1.
Experimental studies corresponded to 41.98% (89), followed by literature reviews (36.32% or 77), ethno-directed interviews (20.28% or 43), studies with association of ethno-directed interviews with experiments (0 .94% or 2) and a comparative study between the results obtained with an ethno-directed study versus random collection (0.47% or 1). Most literature reviews aimed at compiling and associating data from various studies on the same plant species, or set of species, bringing its popular use by traditional communities and associating it with studies of phytochemical composition and biological activity, providing an integralist view of scientific data obtained by previous research, such as the study by Sá and Elisabetsky (2012), who portrayed the development of traditional medical systems in Brazil and by Paim et al. (2020), who discussed 39 species of Connaraceae with pharmacological potential.  In order to better understand the objectives of the articles, the "purpose" of the articles was created and analyzed, as an example of verification of biological activity, phytochemical composition, toxicological profile, among others and their associations ( Table 2). This aimed to distinguish, for example, whether an experimental study was exclusively for phytochemical composition, biological activity, ethno-directed field research, or whether the study made an association of these purposes. The results found showed that the most common types of study were: studies of popular use and biological activity (33.96%), followed by studies of popular use, phytochemical composition and biological activity (21.70%) and ethno-directed survey (20.75%) through field interviews. It is observed that most of the articles had more than one objective/purpose, however, they aimed to understand and establish a relationship between the plant drug and a pharmacological effect, as well as to elucidate which phytochemical components present in plants are responsible for promoting the pharmacological action traditionally reported, like the study by Salehi et al. (2020),
The choice for rural communities can be explained by the fact that these populations have between 80 and 100% more knowledge and practice with traditional medicine compared to populations in large urban centers (Bieski, 2005;Santos, 2009;Bieski et al., 2012) and, in many cases, the studies do not specify the type of rural community surveyed (if extractivists, chestnut trees, "geraizeiros", etc.). Added to this fact is the likely greater lack of access to public health services and low purchasing power, which hinders access to industrialized medicines, making traditional medicine, passed on orally between generations, the main access to health treatments for part of the residents of these communities (Cavaglier & Messeder, 2014;Sales et al., 2015). Quilombola communities, as well as other communities with an African matrix, such as terreiro people, have a peculiar relationship with medicinal plants (Brazil, 2018). While, for some traditional communities, the purely medicinal purpose of the plants has all its cultural meaning, for the "terreiro" peoples, the plants are sacred, containing in them the "axé" or strength of the Orixás (Camargo, 2014;Brazil, 2018, Arruda et al., 2019. This sacralizing appeal, associated with the enhancement and preservation of ancestral knowledge, makes these communities a stronghold of rich traditional knowledge (Arruda et al., 2019). Added to this is the fact that most of these communities are also in rural areas, with rich natural resources that are associated with their cultural reproduction (Ministry of the Environment, 2000;Brazil, 2018;Fernandes et al., 2020).
According to the literature, the use of plants for medicinal purposes in indigenous communities is also notorious (Ministry of the Environment, 2000). Those communities are large holders of traditional systems of medicine that can vary enormously in their sociocultural theoretical concepts regarding the use of these plants (Morais et al., 2005;Tirloni et al., 2011;Ferreira, 2012;Kffuri et al., 2016). As these communities hold important traditional knowledge, a high number of publications involving these communities is likely. However, based on the survey presented here, ethnopharmacological surveys in indigenous communities represented only 6.82% of the total publications analyzed. Among several issues that may be involved in this low percentage, we highlight the delay in bureaucratic negotiations to allow the researcher to enter these lands which, despite being extremely important, lack speed. Among the various bureaucratic processes that must be followed Studies involving people related to popular trade fairs for medicinal plants, such as herbalists, healers and consumers, accounted for 6.82% of the total number of ethnopharmacological articles with field research. This relatively low index is possibly related to the lack of credibility in terms of traditional knowledge regarding therapeutic purposes and the way in which medicinal plants are prepared by the people who sell them (Fraxe et al., 2007). However, these traders can serve as a source of study on some medicinal information on herbs, as well as on the hygienic-sanitary conditions of the popular trade in these vegetables (Neto et al., 2010).
Studies involving riverside communities accounted for 4.55% of the total ethnopharmacological field research.
Although this index is also considered low when compared to the others, and its dispersion is suggested as the main cause, these traditional communities, for the most part, live in the floodplains of the Amazon biome and are holders of vast knowledge regarding the use of medicinal plants, a practice widely referred to in the region as an alternative to the treatment of numerous illnesses (Marques et al., 2020). As the work of doctors and other health agents specialized in these communities is rare, especially in the most isolated places, the traditional populations of the Amazon maintain in traditional medicine and in the use of plants for medicinal purposes the treatment and prophylaxis for various diseases (Fraxe et al., 2007).

Botanical identification and phytochemical composition
According to the results found in the survey, few botanical families were found as representative in the articles, focusing on a single species or genus (Table 3). These results are in agreement with ethnobotanical surveys conducted in other tropical regions, who found the same families as more representative (Lewis, 2005;Pilla et al., 2006). Souza et al. (2014), for example, carried out a study in the region of Carrasco, Ceará (Northeast Brazil), finding as the most representative families Fabaceae (9.52%), Lamiaceae (8.57%), Asteraceae (6.67%) and Euphorbiaceae (5.71%), while Oliveira et al. (2011) in a study carried out in the Pantanal region of Mato Grosso (Center-West), found Fabaceae (10.2%), Asteraceae (7.82%) and Lamiaceae (4.89%). Romanus et al. These data are in accordance with the diversity of these same families, which represent very diverse groups (Stevens, 2001 and constantly updated), including the Brazilian flora, with approximately 3,025, 2,205 and 589 species, respectively (Flora do Brasil 2020). It is also interesting to note that Fabaceae, Asteraceae and Lamiaceae constitute the most diverse families of angiosperm plants (Soltis et al. 2005) that have high secondary metabolism and, therefore, it is expected that they contain a significant concentration of bioactive compounds associated with activities therapeutic and, therefore, extensively studied.
The focus of use on species from similar families showed that phylogenetically close plants (with a high degree of relatedness) used for the same purposes have utilitarian equivalence, that is, they are more likely to have similarities (including chemical) to each other (Reinaldo et al. 2020). In this sense, Reinaldo et al. (2020), demonstrated, in his study, the influence of kinship between groups of plants in the selection of medicinal species among peoples from the semiarid and humid regions of Northeastern Brazil. Although this type of study is still little explored (representing only 0.94% of the articles analyzed), the results seem promising and point to the need for more in-depth investigations, mainly because they indicate that plant identification permeates academic concepts and has a own perspective within the context of traditional knowledge from different communities, with its own botanical identification methods (Reinaldo et al. 2020).
Regarding the studies involving phytochemical analysis with identification of the substances that make up the extracts, they represented 36.8% of the articles analyzed here, taking into account the works where there was an association of this type of analysis with other parameters, such as biological activity and toxicological. Probably, the popularization of equipment and techniques for isolation and identification of substances, such as high-performance liquid chromatography (Maldaner & Jardim, 2009), has a great influence on these data, as well as phylogenetic studies (Soltis et al., 2005).
However, it is important to emphasize that the phytochemical composition can vary according to seasonality, circadian rhythm and phase of plant development, in addition to environmental factors such as temperature, water and nutrient availability, amount of exposure to ultraviolet radiation, altitude, attacks of pathogens, among others (Gobbo-Neto and Lopes 2007), These variations can change the pharmacological response in the dose of the pharmacologically active component in plant drugs and, therefore, the quali-quantitative study of the phytochemical composition of plant drugs, extracts or herbal medicines used in biological activity tests is essential for understanding causality (Cardoso et al., 2017).

Biological activity studies of plants of recognized popular use
Works involving assays of biological activity of plants of recognized popular use (item 1 of Table 2) or fractions of extracts or isolated compounds from them, or even reviews containing this theme, were the most published in Brazil during the 21st century, in which it concerns ethnopharmacology, representing 33.96%, according to the results found in the present study. If considering studies involving the analysis of biological activity associated with other parameters (items 1, 2, 4, 5, 9, 11 and 14 of Table 2), such as toxicological analysis (items 4 and 9 of Table 2) and phytochemical composition (items 2, 4 and 5 of Table 2), this index is 71.70%.
The classification of articles considering the variable "main pharmacological effect" is shown in Table 4.  (Macêdo et al., 2020) and Lippia L. (Oliveira et al., 2006).
Given the current scenario of increasing microbial resistance to classic industrialized antibiotics, research into new antibiotics is of fundamental importance and ethnopharmacology can help in the development, or rediscovery, of new therapeutic approaches based on the synergism of phytochemical compounds, as discussed by Furner-Pardoe and collaborators (2020). According to these authors, the exploration of therapeutic approaches that are not based only on individual compounds, but on a mixture of natural compounds, can result in drugs with potent antimicrobial activity, as established in their study on the anti-biofilm activity of Bald's eye drops (Furner-Pardoe et al., 2020).
Ethnopharmacological studies can also contribute to the establishment of therapies for diseases neglected by the pharmaceutical industry and to expand health care in regions where the local health system is deficient (Veiga & Scudeller, 2015). Veiga and Scudeller (2015), for example, studied the use of sixteen species of medicinal plants widely used in the treatment of malaria and associated diseases in the Amazon region. On the other hand, the use of medicinal plants and herbal medicines for the treatment of other neglected diseases, such as leishmaniasis and parasitosis, has been recognized and encouraged by the World Health Organization (WHO) (Silva et al., 2018).
In addition to neglected diseases, the incorporation of medicinal and herbal plants in health systems, as has been happening in the SUS in Brazil, since the publication of the PNPMF, prioritizing national biodiversity, expands the therapeutic arsenal also for the treatment of everyday diseases, such as inflammation, light infections and injuries, strengthening the health system, as well as the possibilities of using resources associated with biodiversity conservation (Sales et al., 2015).
Consistent feedback from ethnopharmacological studies to traditional communities involves helping to create a therapeutic approach that includes the safe and rational use of medicinal plants within public health systems (Pedroso et al., 2021). For this to occur, it is extremely necessary to integrate traditional knowledge and technical-scientific knowledge to prove the biological activity, which guarantees the pharmacological effect, in addition to toxicity and safety studies, drug interactions and contraindications. In addition, this integration of knowledge and partnership of health systems with traditional peoples is extremely useful for promoting productive methods, such as community gardens, capable of providing medicinal plants that will be used by the public health system (Pedroso et al., 2021).

Final Considerations
The present study indicates that there was a significant increase in publications involving ethnopharmacology in Brazil, especially from 2010, associated with a greater diversification of the objectives in these works (Table 1). Experimental studies were the most numerous, especially experiments to assess biological activity and phytochemical composition of popularly used plants, followed by ethnopharmacological field research, through semi-structured interviews, which took place mainly in rural and "quilombola" communities. The main families of plants used for medicinal purposes were Fabaceae, Asteraceae and Lamiaceae, which are rich in the Brazilian flora and whose pharmacological effects were most analyzed were anti-inflammatory and antimicrobial.
Despite clear advances, ethnopharmacological studies in Brazil still have enormous potential for growth and diversification, both in relation to the traditional communities addressed, and in relation to the proposed objectives, highlighting toxicological and clinical trials, which are still little explored. Furthermore, mechanisms for returning to communities holding the researched traditional knowledge are still incipient, with little or no socioeconomic impact. The improvement of returns, in this sense, could promote awareness of sustainable development, in which traditional knowledge and the environment can be preserved not only for their intrinsic value, but also because they are a source of income and a better quality of life.
However, it is understood that the results found here present an outline of ethnopharmacological research in Brazil and not its entirety, being, however, a first step towards understanding the ethno-directed studies conducted in the country during this century. We recommend new systematic reviews, with expansion of keywords and databases, in addition to metaanalysis, in order to provide a more in-depth view of the development of ethnopharmacology in Brazil in the present century.