S22 - Session O2 - Reunion Island, a tropical hotspot with enormous technological potential for natural sources of plant pigments

Authors: Shamsia Pithon *, Mahery Andriamanantena, Christophe Lavergne, Manon Dijoux, Thomas Petit, Yanis Caro

The search for alternative sources of colorants and pigments has been put forward over the last two decades in numerous industrial sectors such as textile, food, cosmetics and pharmaceutical. Proven toxicity and environmental burdens caused by artificial dyestuffs have motivated industries to turn /switch to natural colorants, and notably those originated from plants. Reunion island possesses a significant number of endemic plant species, as well as native and exotic species, which are rich in pigments of diverse hues. Through the "PLANTIN European project", conducted by the laboratory ChemBioPro (University of La Reunion), in collaboration with the Conservatoire Botanique National de Mascarin (CBNM), and several other partners from Reunion Island, a screening of the tropical plant biodiversity allowed the identification of several promising dyes-producing local plant species. The importance of different physicochemical criteria such as the dye yield, the extracted colors, the plant parts used for the extraction process, the pH and the thermal stability of the dyestuffs, amongst others, have been considered to finally select for the most compelling species for dye application in industries. Alternative extraction procedures including Pressurized Liquid solvent Extraction (PLE) and Ultrasound-Assisted Extraction (UAE) were performed to extract more efficiently the pigments from plant parts. Then, the chemical compounds responsible of the coloration were investigated by HPTLC, flash-chromatography and HPLC/UV-DAD from the crude extracts to identify their chemical nature, stability, and biological properties. For some plant dyestuffs, the chemical families of the main dyes isolated from the color extracts were identified. Several applications related to cosmetics and food industries have been performed with these natural pigments to study their color variation and stability on different substrates by measuring and comparing their color coordinates in the CIEL*a*b* international color system. The Indian Ocean region still offers huge potential for discovering new sources of plant-based dyestuffs. These latter showed highly promising physicochemical properties, consequently offering versatile applications possibilities and opening up new markets. Thus, there is no doubt this is the tip of the iceberg, and many other plants species should be investigated to unveil myriad of other useful compounds.