The Lesser Antilles archipelago comprises about twenty islands extending from the Virgin Islands to Trinidad and Tobago (Figure 1). These islands are the result of subduction between the North American and Caribbean plates [37]-[39]. The archipelago is divided into two main arcs: an ancient external arc, composed of limestone islands, and an active internal arc composed of volcanic islands, separated by an intermediate arc linked to underwater volcanic activities since the Miocene [37]-[39]. This complex and diverse geography, combined with the influence of the region’s tropical climate, promotes exceptional biodiversity despite the modest surface areas of these islands [32][34][35].

Figure 1. Location of the Lesser Antilles archipelago in the Caribbean.

However, volcanic islands are the majority and are characterized by mountain ranges that create a bioclimatic layering. This layering conditions the existence of multiple habitats and favors the installation of a diversity of species, adapted to local conditions and thus forming different forests (Figure 2) [32][34][35].

Figure 2.Ecosystem and bioclimatic potential of the mountainous Lesser Antilles [40].

The Lesser Antilles archipelago contributes to the ecological richness of the Caribbean: one of the hotspots of global biodiversity, notably for Rubiaceae (Figure 3) [32][41].

Figure 3. Some characteristics of Rubiaceae in the Lesser Antilles [2][3].

Ethnobotanical practices in the Lesser Antilles demonstrate a diverse use of plants, deeply rooted in local traditions, influenced by various cultures (Amerindian, African, European, etc.) and having given rise, for example, to a unique, rich and varied traditional medicine [42]-[48]. The local pharmacopoeia includes both indigenous and introduced species, which are now cultivated in private or community gardens. This evolution is the result of a gradual transition from traditional collection in forest environments to more recent domestication [44][49]-[53]. Creole gardens play a central role in the preservation of traditional knowledge and the sustainable management of plant resources by integrating medicinal, food and ornamental plants, witnesses to a syncretic cultural heritage [43][44][46][51][53]-[57].

However, increasing anthropogenic pressure (urbanization, introduction of invasive species, etc.) and new climatic constraints threaten the natural ecosystems and local biodiversity of these islands [32][50][58]. Despite the richness of the pharmacopoeia of the Lesser Antilles, few plants have been included in official pharmacopoeias, which limits their promotion on an international scale [53][59]. Scientific research, particularly in the fields of phytochemistry and pharmacology, remains crucial to validate their therapeutic properties and guarantee safe use [53][59]. The promotion of these species and their economic recognition could thus contribute to more effective preservation of local biodiversity [53].

The main potential uses of Rubiaceae present in the Lesser Antilles, whether specific or not specific to this region, were identified through a preliminary, non-exhaustive and non-in-depth bibliographic search, conducted on online platforms such as “Google Scholar”, “ResearchGate” or “Thèses.fr” or by using published works presenting the uses of plants in the Lesser Antilles.

This bibliographic search was based on keywords including the scientific names of the Rubiaceae listed in the archipelago, in accordance with the regional flora established by Jacques Fournet and Richard Alden Howard [2][3], as well as the terms “uses” or “virtues”. By relying on around a hundred bibliographic references (articles, books or theses, etc.), we were able to identify numerous uses attributed to approximately 77 species of Rubiaceae present in the Lesser Antilles, including one endemic species, Exostema sanctae-luciae (Appendix). The collected data were organized in a table using Excel software, allowing an analysis aimed at identifying and characterizing the main types of possible uses of these plants. In addition, multivariate statistical processing with XLSTAT software made it possible to carry out a factorial correspondence analysis (AFC) in order to illustrate the diversity of the use profiles of Rubiaceae by human populations.

Many uses from various origins, whether traditional or contemporary, are attributed to the Rubiaceae present in the Lesser Antilles, the majority of which are introduced and naturalized (Figure 4).

Figure 4. Diversity of geographical origins of uses recorded for Rubiaceae, all periods combined.

These various uses reflect both the importance of empirical knowledge acquired and transmitted locally depending on the regions of the world where these species are present and the applications resulting from contemporary scientific research. The Rubiaceae illustrate the richness and diversity of uses that humans can make of plants.

The main areas of use identified are distributed variably between the following categories: medicinal, ornamental, industrial and craft, cultural and spiritual, food, agricultural, scientific and technological (Figure 5). Data analysis reveals a predominance of medicinal and ornamental uses, while the other areas, although less represented, show promising potential (Figure 5).

Table 1highlights the diversity of therapeutic approaches, notably through the different types of preparations or possible uses of Rubiaceae, which vary according to the knowledge acquired on the virtues of these plants according to the regions of the world.

Figure 5.Classification of the main categories of use attributed to Rubiaceae, all periods and origins combined.

Table 1.Diversity of types of preparations or possible uses of Rubiaceae.

Although all parts of plants are almost entirely exploited depending on the species and their chemical spectrum (leaves, flowers, fruits, bark, roots, etc.), trees and shrubs occupy a predominant place as shown in Figure 6.

Figure 6. Distribution of physiognomic types by category of use, all periods and origins combined.

Herbaceous plants and shrubs have a notable presence in medicinal or ornamental uses but remain overall very marginal like lianas. This graph nevertheless illustrates the functional and cultural diversity of plants according to their morphology and use. Traditional uses remain predominant but the numerous properties attributed to these species have recently aroused growing interest, leading to an intensification of in-depth scientific research into the use of these plants in different economic sectors (Figure 7).

Figure 7.Estimation of the proportions of traditional and contemporary uses of Rubiaceae.

Using a table composed of 77 columns (Rubiaceae whose uses could be identified) and 7 rows (categories of uses identified), we were able to carry out a factorial correspondence analysis (AFC) (Appendix).

The distance of Khi² allowed to obtain a link between rows and columns, with the value of p (1000) almost similar to the level of significance alpha (0.9999). The F1 and F2 axes support more than 48.42% of the information and give the best possible quality of data representation (Figure 8).

Figure 8. Factorial analysis of correspondences carried out according to the categories of uses of Rubiaceae (Appendix).

This factorial analysis clearly illustrates the diversity of potential uses of Rubiaceae by humans. It demonstrates the knowledge accumulated on their properties across different regions of the world and highlights their significant potential for application in various fields (Figure 8, Appendix). Although the majority of Rubiaceae exhibit a wide variety of use profiles, their therapeutic properties still largely require rigorous validation by scientific research in phytochemistry and pharmacology to ensure safe uses.

We were unable to identify uses for 52 Rubiaceae, including approximately 16 species endemic to the archipelago or strictly endemic to certain islands of the archipelago according to regional flora [2][3]. While many species still seem unknown from the point of view of their chemical composition and therapeutic potential, some Rubiaceae have documented uses.

Medicinal uses

For example, Rubiaceae play an important role in the traditional medicine of the archipelago. Chione venosais a tree used in particular on the island of Grenada, to produce the popular aphrodisiac “Bois Bande”, made from its stem bark and roots [60][61]. The crushed seeds of Coffea arabica (Tree) are used in the French Antilles to treat eye conditions or as a wormer, and the juice or decoction of its roots is said to relieve scorpion stings [20]. Morinda citrifolia (Tree), is used to treat various conditions such as asthma, bronchitis, digestive disorders, urinary tract infections, or to soothe localized pain [18][20][62]. In Dominica, its leaves are applied as a poultice or infused as a tea to relieve rheumatism or stop bleeding on wounds [20].

It is also known that Amerindians, the first peoples to colonize the islands of the archipelago, used the resin of Exostema caribaeum (Tree) against conjunctivitis [7][21], while the endemic species of the archipelago, Exostema sanctae-luciae(Tree), was traditionally used to relieve women after childbirth [21].

In Barbados and Dominica, Chiococca alba, a lianescent shrub, is said to have abortive and/or purgative properties. Hedyotis corymbosa, an herbaceous plant, is considered refreshing: its infusion is used against fever, flu, cough, asthma, as well as for liver and gastric ailments [21]. Furthermore, in Martinique, Dominica and Trinidad, decoctions or infusions of the herbaceous plant Spermacoce verticillata were used to treat flu, fever, bronchitis, colds, constipation and many other ailments [20]. Finally, the fruits and roots of Genipa americana were once exploited for their antibacterial properties in the treatment of venereal diseases, although these uses are now forgotten [20].

All these examples testify to the richness of the bioactive compounds produced by these Rubiaceae at the origin of the various medicinal applications, however the majority of these plants remain under-exploited in the region.

Food uses

Several Rubiaceae are also used for their nutritional and cultural value. Martinique has also become known throughout the world for its excellent coffee culture in the 18th century [63]. The fruits of several species are said to be edible and used in the Caribbean and particularly in the Antilles, such as Alibertia edulis (Shrub), Genipa americana (Tree), or Randia nitida (Tree), [7][16]-[18][20]. These uses come from an ancient domestication of Rubiaceae and an integration into the food and cultural practices of the archipelago.

Ornamental uses

Some Rubiaceae are highly valued for their aesthetic value. Species of several genera including especially Ixora, Gardenia, Mussaenda are used as ornamental plants, especially for their flowers and perfumes [4][3][21][32][64].

These plants (shrubs, shrubs and trees) are easy to maintain and are adapted to tropical climates, which makes them popular for some in private gardens and public spaces [64]. They symbolize vitality and tropical exuberance, reinforcing their ornamental value [32].

Industrial and artisanal uses

Some Rubiaceae are sought after for the quality and robustness of their wood.

Antirhea coriacea, Chimarrhis cymosa and Exostema sanctae-luciae are trees that produce a resistant wood, used in construction or furniture. These species are known for their durability, their resistance to rot, their ability to remain intact in water or their immunity to insects [7][21][32][65]. In addition, the flammable resin of species of the genus Erithalis was once used by Amerindians to make torches, constituting an effective source of lighting [32][66]. These uses demonstrate the practical importance of Rubiaceae in traditional ways of life, closely linked to indigenous knowledge and the oral transmission of knowledge [59].

Cultural and religious uses

The spiritual practices of the Lesser Antilles also include certain Rubiaceae for their symbolism and ritualistic properties. The Amerindians attributed magical and ceremonial functions to certain Rubiaceae, including the emblematic species: Genipa americana(Tree), [20][67]. This species is indeed associated with Amerindian ceremonies, because its fruit was used to produce, by oxidation, a blackish dye traditionally used in ritual tattoos. These practices show a fairly deep interconnection between nature and spirituality in the local cultures of the archipelago.

The Lesser Antilles archipelago is characterized by exceptional wealth, whether physical, biological, ecosystemic or landscape, but whose preservation is endangered by the intensification of human activities since colonization [31][32][68][69]. These tropical island territories, still characterized today by a varied biodiversity and unique ecosystems, are facing major challenges [2][3][32][35][68][69]. The new climatic constraints of this century amplify and add to the varied and negative effects of anthropization: urbanization, massive agricultural exploitation, deforestation, water and soil pollution, introduction of invasive species, further threatening the island ecosystems of the archipelago [32][33][36][58][68][70][71]. Unfortunately, cooperation in terms of natural resource management in the Lesser Antilles has long been limited by weak institutional coordination and significant socio-economic disparities between the islands, which complicated the implementation of integrated regional strategies [69][72].

The application of sustainable development policies even at the island level has not proven to be more effective [73]. Faced with the many environmental challenges, the promotion of the uses of species present in the archipelago constitutes an essential strategy to strengthen cooperation initiatives in terms of conservation, but also to preserve traditional phytotherapeutic practices, while adapting this empirical knowledge to the contemporary requirements of medicine [16]-[21][53][59]. In this regard, the TRAMIL network constitutes a relevant example of regional cooperation for the integration of the uses of plants in the region into a sustainable cultural, heritage and economic approach; by scientifically validating traditional knowledge related to medicinal plants and integrating it into public health systems [17]-[19].

The various categories of uses recorded for species of the Rubiaceae family make this an example. These species are cited for their medicinal virtues to treat various ailments and produce traditional remedies [18][20][60]-[62]. They are also prized for their edible fruits, their ornamental qualities, their robust wood and their artisanal resins [7][16]-[18][20][21][32][64][66]. Finally, some species such as Genipa americana have a strong cultural and spiritual dimension linked to Native American ritual practices [20][67]. The therapeutic properties indicated for these plants in the literature nevertheless require rigorous validation by scientific research in phytochemistry and pharmacology in order to ensure safe uses.