Ethnobotanical and phytochemical studies of Crotalaria species (Fabaceae) from the Vakinankaratra region of Madagascar

This study was conducted to assess the potential of species of the genus Crotalaria (Fabaceae) found in the Vakinankaratra region of Madagascar, with a view to exploiting them in various areas of interest. The work focused on inventorying locally known species, analysing their biogeographical origin, describing their traditional uses and characterising their phytochemical composition. Data from literature reviews and ethnobotanical field surveys identified 19 species of Crotalaria in this region, including 6 endemic (31.6%), 5 native (26.3%) and 8 introduced (42.1%) species. The identified uses fell into 3 categories: medicinal (53%), agronomic (47%), and toxic (32%). Whole plants (45%) and leaves (39%) were the parts used most frequently, while seeds and stem bark were used less frequently (less than 10%). Some species fell into more than one category of use. The most common forms of preparation were based on the use of fresh plants (50%), followed by decoctions, infusions, macerations and steam baths (27%), and powders prepared from plant parts for external use (17%). Endemic species were distinguished by their medicinal and toxic properties, whereas introduced species were mainly used for agricultural and fodder purposes. A phytochemical analysis revealed the presence of alkaloids, flavonoids, tannins and polyphenols, which were bioactive compounds known for their pharmacological and toxic properties. These results highlighted the specific richness of the Crotalaria genus in the Vakinankaratra region, as well as its potential interest for pharmaceutical and agronomic research in Madagascar.