Herbal Medicine: Back to the Future: Volume 2, Vascular Health

Ethnobotany and Plants Used Against Cardiovascular Diseases in the Iberian Peninsula and the Balearic Islands

Airy Gras¹, Montse Parada¹, Teresa Garnatje², Joan Vallès¹, *

¹ Laboratori de Botànica (UB), Unitat associada al CSIC, Facultat de Farmàcia i Ciències de l’Alimentació, Universitat de Barcelona, Av. Joan XXIII 27-31, 08028 Barcelona, Catalonia, Spain

² Institut Botànic de Barcelona (IBB, CSIC-ICUB), Passeig del Migdia s.n., Parc de Montjuïc, 08038 Barcelona, Catalonia, Spain

Abstract

Cardiovascular diseases (CVD) represent one of the most important causes of death all over the world. Consequently, many efforts are invested in their treatment and in the development of drugs that can be useful against these ailments. Plants and plant-derived drugs and functional foods are very important in this respect. On the one hand, molecules obtained from different species of the genus Digitalis (particularly D. lanata and D. purpurea), such as digitalin, digoxin and digoxigenin, are among the most relevant cardiotonic drugs and still come from their natural sources, since their synthesis would be complicated and expensive. On the other hand, many plants are used to cure, palliate or prevent heart, blood vessel and related illnesses at a popular level. As in many other fields of health, folk knowledge has led to both drug development in pharmaceutical industry and herbalist preparation production. Additionally, the direct plant management and use continues to be active at the popular level for this as well as for many other wellness-related purposes. Ethnobotanical research, which inventories the folk plant use in all domains, has been important since old times and has increased its focus on industrialised areas in the recent decades, where it continues to be practised currently. In this chapter we review the state-of-art of herbal medicines that are claimed to be useful for CVD in the Iberian Peninsula and the Balearic Islands. This territory (comprising three states, Andorra, Portugal and Spain, and a small area belonging to the United Kingdom) comprises one of the areas of highest plant biodiversity in Europe and an important linguistic and cultural diversity (Basque, Catalan, Galician, Portuguese, Spanish, and English in Gibraltar), this pointing to a very rich ethnobotanical knowledge. These territories being located in an industrial and economically developed area, certain ailments such as hypertension and hypercholesterolemia are frequent. In addition, functional foods play an important role in the Mediterranean diet, the one typical of the area, and, consequently, in the primary prevention of CVD. We record a total amount of 5,249 use reports of 784 taxa used

against CVD. We analyse the existing ethnobotanical data linked to the cardiovascular system in the area considered, from our own results and from other relevant and representative sources. This review depicts a panorama of the folk use of herbal products to address the quoted ailments, and provides a basis for further (phytochemical, pharmacological and other) research, which could help in the development of medicinal products.

Keywords: Balearic Islands, Cardiovascular System, Ethnobotany, Ethnopharmacology, Folk Plant Uses, Iberian Peninsula.

* Corresponding author Joan Vallès: Laboratori de Botànica (UB), Unitat associada al CSIC, Facultat de Farmàcia i Ciències de l’Alimentació, Universitat de Barcelona, Av. Joan XXIII 27-31, 08028 Barcelona, Catalonia, Spain; E-mail: [email protected]

INTRODUCTION

Cardiovascular diseases (CVD, comprising cardiac illnesses, brain and kidney vascular troubles, and peripheral vascular ailments) represent the most important causes of death all over the world, and concern not only high, but medium and low income countries as well [1]. More than 15 million people died because of CVD in 2010, representing almost 30% of all deaths in the world [2]. Moreover, these kinds of affections are increasing: a prediction foresees more than 23 million people susceptible to death from cardiovascular diseases in 2030 [3]. CVD are the first cause of mortality in Europe too, mortally affecting 4 million people each year, and accounting for 49% of deaths among women and 41% among men [4].

Consequently with the high prevalence of these affections, many efforts are invested in their treatment and in the development of drugs that can be useful against CVD. The American Heart Association reported, for different USA institutions, a budget of more than 34,000 million US dollars in 2015 and proposed one over 37,000 million US dollars for 2016 [5]. In Europe, the EuroHeart: European Heart Health Strategy was implemented in 2007, with 21 participating countries, to fight against CVD [6].

Plants and plant-derived drugs and functional foods are very important in this respect. Estruch et al. [7] reported that a Mediterranean diet (importantly implying plant consumption) supplemented with either extra-virgin olive oil or nuts reduced the incidence of major CVD in people with high risk of developing these troubles. In addition, plants and plant products play a specific role in CVD cure, palliation or prevention at least at two levels.

On the one hand, molecules obtained from different species of the genus Digitalis (particularly D. lanata and D. purpurea), such as digitalin, digoxin and digoxigenin, are among the most relevant drugs historically used as cardiotonic and for other purposes linked to CVD. They are currently among the preferred choice of drugs for these ailments, and still come from their natural sources, since their syntheses are complicated and would be too expensive at the commercial level [8,9]. Apart from this, other plant derivatives are used against CVD [10].

On the other hand, many plants are popularly used to cure, palliate or prevent heart, blood vessel and related illnesses at a popular level. Again dealing with Digitalis products, it is to be mentioned that they not only come from plants, but specifically from folk knowledge about medicinal plant uses [11]. As in many other fields of health, popular knowledge on biodiversity components (particularly plants) has led to both herb-based medicine production and drug development in the pharmaceutical industry [12,13]. Additionally, direct plant management and use continues to be active at the popular level for this as well as for many other wellness-related purposes ([13,14], and references therein).

Ethnobotanical research, which inventories folk plant use in all domains, has been important worldwide since early times, and has increased its focus on industrialised areas in the last decades, where it continues to be practised currently ([14], and references therein). In recent years, medical or pharmaceutical ethnobotany or ethnopharmacology (terms that are almost synonymous and often interchangeably used), without abandoning general ethnofloristic repertories, has pointed to specific troubles or physiological systems and their treatment proceeding from the existing folk knowledge of medicinal plants (see, as a few examples, [13,15-19]). Within the framework of this tendency, CVD treatment with ethnobotanical sources has been addressed [20], as well as the role of local foods (most of them from plant origin) in moderating this kind of affections [21]. Nevertheless, the focus on CVD is not among the most frequent in the sectorial ethnobotanical studies concerning medicinal plant uses.

The Iberian Peninsula and the Balearic Islands constitute one of the areas of the world with a particularly high plant biodiversity. In addition, this territory (comprising three states, Andorra, Portugal and Spain, and a small area belonging to the United Kingdom) holds an important linguistic and cultural diversity. Both facts point to a very rich ethnobotanical knowledge (cf. [22], and the numerous references quoted later, in the results and discussion section of the present work). These territories being located in an industrial and economically developed area, some CVD, such as hypertension and hypercholesterolemia, are frequent. As an example, CVD are responsible for roughly one third of deaths in Spain [23].

Taking into account the richness of the quoted area in terms of both biodiversity and culture, the prevalence of CVD in the territory, and the high rate of ethnobotanical research performed, but the low number of ethnobotanical/ ethnopharmacological papers focusing on CVD therein, the main aim of this chapter is to review the state-of-art of medicinal plants, herbal medicines, functional foods and any other plant-derived product that are claimed by people to be useful for diseases of the cardiovascular system in the Iberian Peninsula and the Balearic Islands. We will analyse the existing ethnobotanical data linked to CVD in the area considered from our own results and from other relevant and representative sources, with the intention of depicting the panorama of the folk use of herbal products to address the quoted ailments, preserving the popular plant knowledge and management data. In addition, we will check the quoted plants in phytotherapeutic and pharmacological literature in order to validate from the experimental viewpoint their uses, providing a basis for further (phytochemical, pharmacological and other) research, which could help in the development of medicinal products.

TERRITORY STUDIED

As stated above, the area covered by the present study comprises the Iberian Peninsula and the Balearic Islands (Fig. 1). This south-western European land of ca. 590,000 km², constituting the western edge of the Mediterranean region, is surrounded by the Atlantic ocean and the Mediterranean sea, and separated from the rest of Europe by the Pyrenees. It includes Andorra, mainland Portugal, mainland Spain, the Balearic archipelago and the British overseas territory of Gibraltar. The extra-Iberian Portuguese and Spanish territories have not been considered, since we do not aim at studying the complete territories of the states but, rather, areas identified by both biogeographical and cultural characteristics.

Fig. (1))

Studied area, with its location in Europe and its territorial structure. Dots indicate the areas where literature information analysed in the present work come from.

The area considered coincides with the one covered by Flora iberica [24]. It is floristically the richest region in Europe, with ca. 7,500 plant taxa at specific and subspecific levels, and includes and hosts an elevated number of biodiversity hotspots in terms of plant taxa number and endemism, notably the Pyrenees, and the central and south-eastern Spanish mountain ranges [25,26]. From sea-level to almost 3,500 m of altitude, the landscape of the Iberian-Balearic area belongs basically to the Mediterranean and Euro-Siberian biogeographic regions [27-29]. More details, with 10 phytogeographic sectors characterised by geological and climatic facts, can be found in [30].

With around 50,000,000 inhabitants, the linguistic and cultural diversity of the territory studied is also rich. The languages spoken in the Iberian Peninsula and the Balearic Islands are basically Basque, Catalan, Galician/Portuguese and Spanish. Catalan is the official language in Andorra, Portuguese in Portugal, Spanish in Spain, where Basque, Catalan and Galician are also official in some areas, and English in Gibraltar. In addition, Asturian/Leonese and Aragonese languages are spoken in small areas in Spain with no official status, and the Occitan language (locally called Aranese) is also spoken in a small Spanish territory, and has an official status, together with Catalan and Spanish. More details on Iberian languages and linguistic areas can be found in [31,32].

The flora of the Iberian area is rather well-known, and a project initiated more than 30 years ago is about to end, with an inventory of vascular plants including their popular names in the Iberian languages, as data linked to ethnobotany [24]. As for the ethnoflora, it has been profusely studied starting with the Catalan botanist Pius Font i Quer, who grouped his observations in this field in a seminal book [33]. Later, Mulet [34] was pioneer in the region in performing a PhD thesis on this subject, which has been followed by a large number of academic works. The territory considered is nowadays one of the most thoroughly prospected in Europe from the ethnobotanical viewpoint. A book of ethnobotany in Andorra [35], a very small country, and the first volume (out of 5-7 foreseen) of the Spanish inventory of popular knowledge linked to biodiversity [22], a work compiling many others in the area quoted, together with numerous studies developed in Portugal, account for this situation (see references, object of the present review, in the literature list). Even work specifically dealing with the focus of the present paper, CVD, has been published within the area considered [20].

METHODOLOGY

The basis for the present study consisted of a review of ethnobotanical works representing all the territories in the Iberian-Balearic area but Gibraltar, a very small area for which we did not detect any publication with this focus. At least one (in most cases, many more) work per political and/or cultural area has been consulted. The territories are identified and those with works concerning them are marked in Fig. (1). All sources employed are primary in the sense that we only considered works collecting and reproducing data directly obtained through ethnobotanical and/or ethnopharmacological interviews with people rooted in the studied area. The literature reviewed does not therefore include any work with information not coming from popular plant management and use in the Iberian lands, even though an important amount of books on medicinal plants, without folk knowledge at the basis, is available there. The complete corpus consists of 81 works, which are quoted in the literature list.

Each work has been read in detail and all data linked to CVD have been identified and tabulated in an Excel document. The scientific name and popular uses in all cases, and used part of plant, form of preparation, and posology, whenever available, were collected. On some occasions, complementary information has been annotated as well. A categorisation of the uses was compiled prior to reading the works, since they contain many different, often popular expressions to name uses that are in some cases coincidental (see the subheading Ailments addressed in the Results and Discussion section). Once all data had been tabulated, some numerical analyses were performed.

Apart from reviewing the Iberian ethnobotanical sources in the aspects related to CVD, to confirm the specific uses reported in the works considered, we additionally analysed the literature to carry out a phytotherapeutic and pharmacological validation of uses related to CVD of most reported plants, using monographs (often linked to databases) from official sources [36-38], together with non-official but encyclopaedic bibliography on phytotherapy [38-40].

For plant names and authorities we follow The Plant List (http://www. theplantlist.org), and for family assignation we follow APG IV [41].

RESULTS AND DISCUSSION

The total number of plant taxa claimed to be useful to cure, palliate or prevent CVD in the Iberian Peninsula and the Balearic Islands is 784, 24 of which were determined only at generic level. The remaining 760 include 713 species and 47 subspecies. All these taxa belong to 388 genera and 109 families. The number of use reports detected of these taxa referring to CVD is 5,249. We consider here a use report each citation of the use of one plant taxon prepared in one determined form for one CVD in one work; if in the same work one of the conditions (the part of the plant, its preparation form or the CVD addressed) varies, this accounts not for one but for several use reports. Out of the 784 taxa, 304 have been reported only once (i.e. one quotation of one use of the plant in one territory).

Table S1 (provided, given its length, as supplementary material at the end of the text) presents the list of the plants employed against CVD in the territory considered, with indications of the particular uses and the areas where they have been recorded, and Table 1 includes more detailed information on the 25 most quoted plants.

Table 1 The 25 most quoted plants for CVD, with indication of troubles addressed, parts of plants used, preparation and administration forms, number of use reports and coincidences with the literature pharmacological validation set as follows: (1) [36]; (2) [37]; (3) [38]; (4) [39]; (5) [40].

Taxa Used and Use Reports

The five most represented plant families are Lamiaceae (658 use reports, 12.54%), Rosaceae (466, 8.88%), Asteraceae (460, 8.76%), Urticaceae (320, 6.10%) and Apiaceae (228, 4.34%). Four of these families are classically among the top ones in most works on Mediterranean ethnobotany ([42,43], and references therein): Lamiaceae, Rosaceae, Asteraceae and Apiaceae are big in terms of number of taxa (Asteraceae being the biggest in this sense in plants), cosmopolitan and well represented in the territories