S22 - Session O2 - New sources of natural colorants for the industries from Madagascar Island dye plants

Authors: Mahery Andriamanantena *, Pascal Danthu, Fanjaniaina Fawbush-Razafimbelo, Béatrice Raonizafinimanana, Thomas Petit, Yanis Caro

Madagascar is a world hotspot of biodiversity, with an endemism rate close to 80%. Its flora therefore represents a potential reservoir of bio-compounds, the development of which represents a scientific, economic but also environmental challenge. Today, the harmfulness of petrochemical dyes for both human health and the environment is established. An alternative relies on the production of natural dye via green chemistry processes. Our research, based on previous work and local empirical knowledge, proposes, in a first step, to identify the dyeing potential of Malagasy plants through a screening of possible sources of natural dyes and pigments. In a second step, some species were selected for a more in-depth characterization of the raw extracts. Thus, 128 dye plants, of which 34 are endemic, have been identified. Five sources of yellow and red colors were retained: the barks of Acridocarpus excelsus and Harungana madagascariensis , the roots of Paracarphalea kirondron and Woodfordia fruticosa , the leaves of Tectona grandis . The main chemical families identified in the crude extracts of these species are polyphenols, flavonoids, tannins, xanthonoids and quinonoids. HPCL/DAD/MS analysis of Paracarphalea kirondron demonstrated a high concentration of different quinonoids with potentially unknown molecules. Moreover, most of the pigments extracted from these five plants, show a very good stability towards pH and high temperatures (up to 200°C). Some species showed high antioxidant properties. Finally, an acute toxicity test performed on the zebrafish model showed that most of these extracts are less toxic than the usual artificial dyes. The diversity of dye plants in Madagascar is a promising source of natural dyes that can replace artificial dyes. However, the supply of a production chain for these dyes implies the respect of the rights of local actors and the implementation of actions to manage this biodiversity in a sustainable way.