Ecological Theories and Major Hypotheses in Ethnobotany: Their Relevance for Ethnopharmacology and Pharmacognosy in the Context of Historical Data

An updated inventory of medicinal and ritual plants of southern Africa

ETHNOPHARMACOLOGICAL RELEVANCE

For the first time in two decades, a comprehensive, up-to-date overview of the medicinal and ritual plants of southern Africa is presented. This data is analysed and compared with a previous survey done in 2002.

STUDY AIM

The main aim is to update the checklist of medicinal and ritual plants of southern Africa and to determine the number of new records since 2002. We also provide a high-level perspective on the selection of medicinal and ritual plant species in southern Africa, a taxonomic analysis of the new checklist as well as a chronological perspective on the citation of medicinal and ritual species before and after 2002.

MATERIALS AND METHODS

The most recently published medicinal and ritual plants checklist for southern Africa was reviewed and updated. A wide range of ethnobotanical literature, including books, field guides and electronic journals, was used. All calculations were done by using formulas and functions in Microsoft Excel and R Studio.

RESULTS

4120 medicinal and ritual taxa and 3784 medicinal and ritual species have been recorded. Compared with the 2002 checklist, there are 1239 new taxa (1228 new species). A strong correlation between available taxa and selected medicinal taxa exists on order level, which corresponds with the results of an analysis done in 2008. The top 10 species-rich medicinal plant families of southern Africa are Asteraceae, Fabaceae, Apocynaceae, Euphorbiaceae, Asphodelaceae, Malvaceae, Lamiaceae, Poaceae, Rutaceae and Rubiaceae. Different patterns of plant family representation can be seen across certain cultural healing systems of southern Africa. The species popularity (number of citations) of Hypoxis hemerocallidea Fisch. & C.A.Mey. Has increased substantially after 2002. Other medicinal and ritual plant species have been consistently researched, such as Artemisia afra Jacq. ex Willd., Carpobrotus edulis (L.) L.Bolus, Aloe ferox Mill., Leonotis leonurus (L.) R.Br. and Gunnera perpensa L.

CONCLUSIONS

The numerous new medicinal and ritual plant records that have been reported in the last two decades provide evidence of an incompletely documented ethnobotanical heritage that urgently requires documentation. Patterns of taxonomic diversity on family level indicate distinctive differences between cultural healing systems. Signs of the adaptability and dynamics of traditional healing systems in southern Africa can be seen in the changes in the citation of species over time.

Medicinal plants used by minority ethnic groups in China: taxonomic diversity and conservation needs

ETHNOPHARMACOLOGICAL RELEVANCE

Indigenous communities have long relied on medicinal plants (MPs) for primary healthcare. The ethnomedicinal knowledge are different among ethnic groups since the local flora and people's health beliefs generally vary among biocultural backgrounds. China with its diverse biocultural environment is rich in culturally important plant species including MPs. They are also essential in the context of conservation of plant resources and the related traditional medical knowledge, requiring an integrated perspective on these MPs.

AIM OF THE STUDY

Focusing on the MPs used by the minority ethnic groups, this study assesses the diversity of MPs in China used in local indigenous traditions, as well as their conservation needs.

MATERIALS AND METHODS

The MPs used by the 18 selected minority ethnic groups were extracted from an ethnic MP dictionary. After standardizing, the names then were compiled as an inventory. Next, following statistics were computed: the number of species in each order and family, species used by each ethnic group, species documented in the national herbal resource dataset, species adopted in drug standards, and species at different levels of conservation lists. The overall similarity of the MPs used by the ethnic groups included was achieved using a cluster and principal component analysis.

RESULTS

In total 5886 vascular plant species are reported as medicines in the 18 ethnic groups, which belong to 1657 genera and 243 families. It is found that 3195 species are used exclusively by one ethnic group, indicating their cultural salience and potential restrictedness in ecological terms. Moreover, 1159 species are included in national / regional drug standards, indicating their importance in the national medical flora. However, only 3541 species of them are documented in the national herbal resource dataset, and 761 species are at different levels of threatened status, highlighting the conservation needs of Chinese MPs and the related traditional medical knowledge.

CONCLUSIONS

Using a quantitative approach, for the first time the present study reveals the high level of taxonomic diversity of MPs used by minority ethnic groups of China. However, of these species, 40% are still not inventoried in the national herbal resource dataset, and more than half are used exclusively by one ethnic group, and around 13% are included in the conservation lists of different levels. These together urge the conservation of MP resources and related traditional medical knowledge. Additionally, we recommend fostering the cross-cultural communication the regional ethnomedicinal knowledge, for the purpose of maximizing the benefits of regional plants to human.

Food drugs as drivers of therapeutic knowledge and the role of chemosensory qualities

ETHNOPHARMACOLOGICAL RELEVANCE

Chemosensory qualities of botanical drugs are important cues for anticipating physiologic consequences. Whether a botanical drug is used for both, food and medicine, or only as medicine depends on taste preferences, nutritional content, cultural background, and the individual and overall epidemiological context.

MATERIAL AND METHODS

We subjected 540 botanical drugs described in De Materia Medica having at least one oral medical application to a tasting panel. The 540 drugs were grouped into those only used for medicine (388) and those also used for food (152). The associations with chemosensory qualities and therapeutic indications were compared across the two groups. We considered 22 experimentally assessed chemosensory qualities and 39 categories of therapeutic use groups. We wanted to know, 1): which chemosensory qualities increase the probability of an orally applied botanical drug to be also used for food ? 2): which chemosensory qualities augment the probability of an orally applied botanical drug to be only used for medicine? and 3): whether there are differences in therapeutic indications between orally applied botanical drugs also used for food (food drugs) and botanical drugs applied exclusively for medicinal purposes (non-food drugs) and, if yes, how the differences can be explained.

RESULTS

Chemosensory qualities augmenting the probability of an orally applied botanical drug to be also used for food were sweet, starchy, salty, burning/hot, fruity, nutty, and cooling. Therapeutics used for diarrhoea, as libido modulators, purgatives, laxatives, for expelling parasites, breast and lactation and increasing diuresis, were preferentially sourced from food drugs while drugs used for liver and jaundice, vaginal discharge and humoral management showed significant negative associations with food dugs in ancient Greek-Roman materia medica.

CONCLUSION

Therapeutics used for ailments of body organs involved in the digestion of food and the excretion of waste products showed a tendency to be sourced from food drugs. Arguably, the daily consumption of food offered the possibility for observing post-prandial physiologic and pharmacologic effects which led to a high therapeutic versatility of food drugs and the possibility to understand benefits of taste and flavour qualities. The difference in chemosensory qualities between food drugs and non-food drugs is demarcating the organoleptic requirements of food rather than that of medicine.

Are we romanticizing traditional knowledge? A plea for more experimental studies in ethnobiology

In answer to the debate question "Is ethnobiology romanticizing traditional practices, posing an urgent need for more experimental studies evaluating local knowledge systems?" I suggest to follow-up on field study results adopting an inclusive research agenda, and challenge descriptive data, theories, and hypotheses by means of experiments. Traditional and local knowledge are generally associated with positive societal values by ethnobiologists and, increasingly also by stakeholders. They are seen as a way for improving local livelihoods, biocultural diversity conservation and for promoting sustainable development. Therefore, it is argued that such knowledge needs to be documented, protected, conserved in situ, and investigated by hypothesis testing. Here I argue that a critical mindset is needed when assessing any kind of knowledge, whether it is modern, local, indigenous, or traditional.

Medicinal plants meet modern biodiversity science

Plants have been an essential source of human medicine for millennia. In this review, we argue that a holistic, interdisciplinary approach to the study of medicinal plants that combines methods and insights from three key disciplines - evolutionary ecology, molecular biology/biochemistry, and ethnopharmacology - is poised to facilitate new breakthroughs in science, including pharmacological discoveries and rapid advancements in human health and well-being. Such interdisciplinary research leverages data and methods spanning space, time, and species associated with medicinal plant species evolution, ecology, genomics, and metabolomic trait diversity, all of which build heavily on traditional Indigenous knowledge. Such an interdisciplinary approach contrasts sharply with most well-funded and successful medicinal plant research during the last half-century, which, despite notable advancements, has greatly oversimplified the dynamic relationships between plants and humans, kept hidden the larger human narratives about these relationships, and overlooked potentially important research and discoveries into life-saving medicines. We suggest that medicinal plants and people should be viewed as partners whose relationship involves a complicated and poorly explored set of (socio-)ecological interactions including not only domestication but also commensalisms and mutualisms. In short, medicinal plant species are not just chemical factories for extraction and exploitation. Rather, they may be symbiotic partners that have shaped modern societies, improved human health, and extended human lifespans.

Integrating depth and rigor in ethnobiological and ethnomedical research

Ethnobiology and ethnomedicine, traditionally descriptive disciplines chronicling Indigenous People and Local Community (IPLC) practices, face the challenge of incorporating hypothesis-driven research to address contemporary issues. This paper argues for a synergistic approach where both approaches are valued for their unique contributions to understanding human-nature interactions and informing policy.

Descriptive ethnobotanical studies are needed for the rescue operation of documenting traditional knowledge

In this essay, I claim that the primary aim of ethnobiological research is now to document disappearing traditional knowledge. This is an absolute priority due to the rate at which biocultural biodiversity in the world is disappearing. Rather than diverting our efforts into inflating the theoretical part of ethnobotany, we should concentrate on knowledge documentation to facilitate its circulation in the communties that hold it or at least to preserve it for future generations, even in the static form of databases or video recordings.

Treating leishmaniasis in Amazonia, part 2: Multi-target evaluation of widely used plants to understand medicinal practices

ETHNOPHARMACOLOGICAL RELEVANCE

Leishmaniasis are widely distributed among tropical and subtropical countries, and remains a crucial health issue in Amazonia. Indigenous groups across Amazonia have developed abundant knowledge about medicinal plants related to this pathology.

AIM OF THE STUDY

We intent to explore the weight of different pharmacological activities driving taxa selection for medicinal use in Amazonian communities. Our hypothesis is that specific activity against Leishmania parasites is only one factor along other (anti-inflammatory, wound healing, immunomodulating, antimicrobial) activities.

MATERIALS AND METHODS

The twelve most widespread plant species used against leishmaniasis in Amazonia, according to their cultural and biogeographical importance determined through a wide bibliographical survey (475 use reports), were selected for this study. Plant extracts were prepared to mimic their traditional preparations. Antiparasitic activity was evaluated against promastigotes of reference and clinical New-World strains of Leishmania (L. guyanensis, L. braziliensis and L. amazonensis) and L. amazonensis intracellular amastigotes. We concurrently assessed the extracts immunomodulatory properties on PHA-stimulated human PBMCs and RAW264.7 cells, and on L. guyanensis antigens-stimulated PBMCs obtained from Leishmania-infected patients, as well as antifungal activity and wound healing properties (human keratinocyte migration assay) of the selected extracts. The cytotoxicity of the extracts against various cell lines (HFF1, THP-1, HepG2, PBMCs, RAW264.7 and HaCaT cells) was also considered. The biological activity pattern of the extracts was represented through PCA analysis, and a correlation matrix was calculated.

RESULTS

Spondias mombin L. bark and Anacardium occidentale L. stem and leaves extracts displayed high anti-promatigotes activity, with IC₅₀ ≤ 32 μg/mL against L. guyanensis promastigotes for S. mombin and IC₅₀ of 67 and 47 μg/mL against L. braziliensis and L. guyanensis promastigotes, respectively, for A. occidentale. In addition to the antiparasitic effect, antifungal activity measured against C. albicans and T. rubrum (MIC in the 16-64 μg/mL range) was observed. However, in the case of Leishmania amastigotes, the most active species were Bixa orellana L. (seeds), Chelonantus alatus (Aubl.) Pulle (leaves), Jacaranda copaia (Aubl.) D. Don. (leaves) and Plantago major L. (leaves) with IC₅₀ < 20 μg/mL and infection rates of 14-25% compared to the control. Concerning immunomodulatory activity, P. major and B. orellana were highlighted as the most potent species for the wider range of cytokines in all tested conditions despite overall contrasting results depending on the model. Most of the species led to moderate to low cytotoxic extracts except for C. alatus, which exhibited strong cytotoxic activity in almost all models. None of the tested extracts displayed wound healing properties.

CONCLUSIONS

We highlighted pharmacologically active extracts either on the parasite or on associated pathophysiological aspects, thus supporting the hypothesis that antiparasitic activities are not the only biological factor useful for antileishmanial evaluation. This result should however be supplemented by in vivo studies, and attracts once again the attention on the importance of the choice of biological models for an ethnophamacologically consistent study. Moreover, plant cultural importance, ecological status and availability were discussed in relation with biological results, thus contributing to link ethnobotany, medical anthropology and biology.

The relevance of quantitative ethnobotanical indices for ethnopharmacology and ethnobotany

ETHNOPHARMACOLOGICAL RELEVANCE

As an interdisciplinary field of research ethnopharmacology draws on methodologies and methods from a variety of disciplines. A range of ethnobotanical indices are frequently used to transform primary data obtained through field studies into statistical measures. These indices are claimed to serve as a proxy for efficacy or drug discovery (Fidelity Level 'FL') and to show the importance of botanical drugs and plants used as medicines (Relative Importance 'RI', Use Value 'UV' or Cultural Importance Index 'CI', Cultural Value Index 'CV', Relative Frequency of Citation 'RFC'). This is, however, doubtful, as these indices have not been developed by statisticians, nor by pharmacologists while a proof of concept is lacking. Moreover, the question whether a simple number can summarize the cultural value or importance of plants is not only mathematical but also epistemological.

MATERIAL AND METHODS

The FL, RI, UV/CI, CV and the RFC are shortly reviewed. Their statistical rigour is explained and the relevance for ethnobotany, ethnopharmacology and drug discovery discussed.

RESULTS

The effect of the sample size on the dispersal of data and the differential probability of botanical drugs being used for the different categories of use are not being considered by these indices. They lack statistical rigour and are simple percentage calculations. Moreover, important factors influencing plant use, such as the availability of pharmaceutical drugs, or the severity of diseases covered by the use-categories, are not accounted for.

CONCLUSION

Especially unexperienced and young researchers may be ensnared by using ethnobotanical indices to describe their field data. However, the cultural value and importance of plants in general, and more specifically, of medicinal plants and botanical drugs cannot be summed up by numbers. The discussed indices encrypt parts of the primary data but fail to show the value or importance of plant use because the reasons for which plants are valued or important to people are far more complex than what the formulations of these indices suggest. The indices also lack the power to pinpoint plant species or botanical drugs for drug discovery that contextualized primary data has. Botanical drugs may be useful for a range of disorders or only for specific indications, according to their pharmacologic properties. Therefore, the exclusiveness of therapeutical applications (FL) does not serve as a proxy for effectiveness. The solution is to use and understand the contextualized primary data.

What's the choice for goji: Lycium barbarum L. or L. chinense Mill.?

ETHNOPHARMACOLOGICAL RELEVANCE

For over one millennium, goji berries have been used traditionally as food and medicine in eastern Asia. In recent decades, it has become increasingly popular globally. However, the biocultural development of goji is poorly known. The botanical origin of goji is controversial: in many but not all modern regional or international quality standards, L. barbarum is accepted exclusively as the botanical origin of goji.

AIM OF THE STUDY

Focusing on historical, biogeographical, botanical, phytochemical and pharmacological data, the overarching aim is to understand the biological origin of goji's historical uses, as well as whether the two species can be used interchangeably.

MATERIALS AND METHODS

The taxonomic literature on L. barbarum and L. chinense were analysed, followed by a study of botanical specimens and fieldwork. Historical herbals and gazetteers were employed to define the historical producing areas and medical properties of goji. An identification of the species used in history was carried out. In a final step the phytochemical and pharmacological literature on the species was compared.

RESULTS AND DISCUSSION

Due to their morphological similarity and different accessibility, fruits of both L. barbarum and L. chinense have been used interchangeably as food and medicine at least since 682 CE. While the fruit of L. barbarum was recognized to be superior in quality, the fruit of L. chinense was commonly used as an equivalent because of its easier accessibility. Cultivation of L. barbarum in China since 1960s improved its availability, which likely lead to its exclusive use as source of goji in China. The long-term safe use with no reported major safety concerns supports that these two species both are useful sources for medicinal Lycium.

CONCLUSIONS

Medicinal plants had been used traditionally long before they were named in scientific nomenclature system. Therefore, the understanding of traditional herbal knowledge and the adequate use of those traditional medicines require a reliable identification based on archival records. This study developed an approach for the identification of species used historically, with an integrated analysis of specimens, historical herbals, and national gazetteers. Additionally, their different chemical profiles and pharmacological activities indicate that they should not be used interchangeably. Further scientific evidence is required for their safe and effective use.

Utilitarian redundancy in local medical systems - theoretical and methodological contributions

The utilitarian redundancy model (URM) is one of the recent contributions to ethnobiology. We argue that URM can be applied to access use-pressure on plant species, the resilience of socioecological systems (e.g., local medical systems), cultural keystone species, and the role of exotic species in social-ecological systems. Based on previous URM studies, we also emphasize the need to differ practical (considering plants and uses that are currently employed) and theoretical (considering both currently employed and potentially employed plants and uses) redundancy. Based on the main applications of the URM, we propose a new index to access redundancy of a therapeutic indication: the Uredit, so that Uredit = NSp + CR, were Uredit is the Utilitarian Redundancy Index for the therapeutic indication; NSp is the total number of species mentioned for the indication, and CR is the species' contribution to redundancy (in terms of knowledge sharing). The maximum value that the Uredit could reach is twice the number of species employed for the therapeutic indication. We believe that this theoretical and methodological improvement in the model can improve comparisons of redundancy in different social-ecological systems. We also highlight some limitations of the URM (and our Uredit), and we believe that conscious reasons behind people's decisions should be incorporated into future studies on the subject.