Abstract: Structure and composition of coastal forested wetlands are mainly controlled by local topography and soil salinity. Hydrology plays a major role in relation with tides, seaward, and freshwater inputs, landward. We report here the results of a two-year study undertaken in a coastal plain of the Guadeloupe archipelago (FWI). As elsewhere in the Caribbean islands, the study area is characterized by a micro-tidal regime and a highly seasonal climate. This work aimed at understanding groundwater dynamics and origin (seawater/freshwater) both at ecosystems and stand levels. These hydrological processes were assessed through 18O/16O and 2H/1H isotopic analyses, and from monthly monitoring of water level and soil salinity at five study sites located in mangrove (3) and swamp forest (2). Our results highlight the importance of freshwater budget imbalance during low rainfall periods. Sustained and/or delayed dry seasons cause soil salinity to rise at the mangrove/swamp forest ecotone. As current models on climate change project decreasing rainfall amounts over the inner Caribbean region, one may expect for this area an inland progression of the mangrove forest to the expense of the nearby swamp forest. © 2015 by the authors.

Abstract: Ethnopharmacological relevance: Cutaneous leishmaniasis is a neglected disease with a high incidence in French Guiana, mainly in the middle and upper Oyapock basin, where Amerindian and some Brazilian people live. The main goals of this work were (i) to assess the knowledge about leishmaniasis in the different populations of the middle and upper Oyapock basin, (ii) to study the therapeutic strategies adopted by people affected by leishmaniasis and (iii) to document the use of phytotherapeutic remedies for leishmaniasis. Knowledge, attitudes and practices (K.A.P.) related to this disease and its treatments have been studied according to cultural group and geographical settlement. Within the Wayãpi group, the evolution of the knowledge of phytoremedies over the last 20 years has been characterised by literature-based comparisons. Materials and methods: A total of 144 questionnaires were administered in all the villages of the upper Oyapock and Camopi basins. Correspondence analyses were used for multivariate analysis. Plant species were identified at the Cayenne Herbarium (CAY). Results: The biomedical concept of leishmaniasis correlates well with the Teko and Wayãpi concepts of kalasapa and kalasapau. Although the vector of this disease was not correctly identified, the most commonly cited aetiology (74.5%) was vector-borne, and related epidemiological schemes correlate well with the one encountered in French Guiana. Theoretically and practically, health centres were the most commonly used resource for diagnostic in instances of leishmaniasis infection (65.9%), independently of the patient's cultural group, along with the use of pharmaceutical drugs (85.3%). Pharmaceuticals were commonly utilised despite the frequent (51.5%) use of phytotherapeutic remedies, alone or in combination with drugs. The most cited medicinal plant species for the treatment of leishmaniasis included Eleutherine bulbosa (Mill.) Urb. (Iridaceae, cited 14 times), Euterpe oleracea Mart. (Arecaceae, 9), Cecropia obtusa Trecul (Cecropiaceae, 8), Jatropha curcas L. (Euphorbiaceae, 7), Ceiba pentandra (L.) Gaertn. (Bombacaceae, 6) and Carica papaya L. (Caricaceae, 6). Multiple correspondence analyses demonstrated that the species used in leishmaniasis remedies are more prone to vary by the user's place of residence than by their cultural origin, which indicates that exchange of knowledge about leishmaniasis remedies has occurred across different cultural groups. Literature-based comparisons between the remedies for leishmaniasis used by the Wayãpi during the 1980s showed a striking evolution, both in terms of diversity of species and number of plants used. The large number of species shared with other Guianese groups argues for intercultural exchange and may explain the majority (57.1%) of the newly used species highlighted in our study. Conclusions: Leishmaniasis is a well-known disease in the studied area. Phytotherapeutic treatments are still in use, although they are not the main source of remedies, and should undergo pharmacological studies to evaluate their potential therapeutic value. © 2011 Elsevier Ireland Ltd. All rights reserved.

Abstract: A new quassinoid Picrasin K 1 was isolated from a decoction made of Quassia amara leaves, traditionally used in French Guyana to treat malaria. The structure and relative stereochemistry of 1 was determined through extensive NMR analysis. Picrasin K showed a low activity against Plasmodium falciparum in vitro (IC 50 = 8 μM), and a similar low activity on human cancerous cells line (IC 50 = 7 μM on MCF-7 cells line). © 2011 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.

Abstract: Ants (Formicidae) represent a taxonomically diverse group of hymenopterans with over 13,000 extant species, the majority of which inject or spray secretions from a venom gland. The evolutionary success of ants is mostly due to their unique eusociality that has permitted them to develop complex collaborative strategies, partly involving their venom secretions, to defend their nest against predators, microbial pathogens, ant competitors, and to hunt prey. Activities of ant venom include paralytic, cytolytic, haemolytic, allergenic, pro-inflammatory, insecticidal, antimicrobial, and pain-producing pharmacologic activities, while non-toxic functions include roles in chemical communication involving trail and sex pheromones, deterrents, and aggregators. While these diverse activities in ant venoms have until now been largely understudied due to the small venom yield from ants, modern analytical and venomic techniques are beginning to reveal the diversity of toxin structure and function. As such, ant venoms are distinct from other venomous animals, not only rich in linear, dimeric and disulfide-bonded peptides and bioactive proteins, but also other volatile and non-volatile compounds such as alkaloids and hydrocarbons. The present review details the unique structures and pharmacologies of known ant venom proteinaceous and alkaloidal toxins and their potential as a source of novel bioinsecticides and therapeutic agents. © 2016 by the authors; licensee MDPI, Basel, Switzerland.

Abstract: Tropical forests store large amounts of biomass despite they generally grow in nutrient-poor soils, suggesting that the role of soil characteristics in the structure and dynamics of tropical forests is complex. We used data for >34 000 trees from several permanent plots in French Guiana to investigate if soil characteristics could predict the structure (tree diameter, density and aboveground biomass), and dynamics (growth, mortality, aboveground wood productivity) of nutrient-poor tropical forests. Most variables did not covary with site-level changes in soil nutrient content, indicating that nutrient-cycling mechanisms other than the direct absorption from soil (e.g. the nutrient uptake from litter, the resorption, or the storage of nutrients in the biomass), may strongly control forest structure and dynamics. Ecosystem-level adaptations to low soil nutrient availability and long-term low levels of disturbance may help to account for the lower productivity and higher accumulation of biomass in nutrient-poor forests compared to nutrient-richer forests.