Mas-Normand Lindsay's thesis “New analytical developments for the metabolomics and annotation of dye plant extracts: Applications in a cultural heritage context”.”

Mrs. Mas-Normand Lindsay, doctoral student at IMBE, team Ecology, Ecotoxicology & Chemistry applied to Agroecology and Restoration, will publicly defend his thesis work on Wednesday 10 December 2025, at 9:30 am in L'Amphithéâtre Agrosciences, Avignon. To follow the viva via distance learning.

In front of a jury made up of :

• Émilie Destandau, Professor, University of Orléans, Rapporteur
• Ms Audrey Le Gouellec, Senior Lecturer, HDR, Grenoble Alpes University, Rapporteur
• Joël Boustié, Professor, University of Rennes 1, Examiner
• Thibaut Devièse, Senior Lecturer, HDR, Aix Marseille University, Examiner
• Gérald Culioli, Professor, Avignon University, Thesis supervisor
• Olivier Dangles, Professor Emeritus, Avignon University, Thesis co-supervisor
• Ms Carole Mathe de Souza, Senior Lecturer, HDR, Avignon University, Thesis co-supervisor

Summary of work:

Natural dyes were used by mankind to dye fabrics and various everyday objects until the end of the 19th century. Today, historians, museum curators and scientists are trying to decipher the secrets of heritage objects, to better understand their history and preserve them. Thanks to the data collected, it is sometimes possible to trace back the techniques and materials used to dye them, or the exchange of raw materials and know-how. A wide range of analytical techniques can be used to obtain such information. However, it is often difficult to trace the exact botanical origin of the natural dyes identified in an object, particularly in the case of the colour yellow. In fact, this colour can be obtained from a wide variety of dye plants, and many compounds are commonly found in several of them.

In order to propose a method for accurately identifying the botanical origin of the dyes used to dye heritage objects, and also to better characterise the impact of dyeing and degradation conditions on their compositions in dye molecules, a non-targeted metabolomics approach is proposed as part of this thesis work. Metabolomics has already proved its worth in studies of environmental stress, the discovery of biomarkers and the search for bioactive molecules, but its use is still anecdotal in heritage chemistry.

The first objective of this thesis was to develop a non-targeted metabolomics approach, using LC-HRMS/MS and annotation tools such as molecular networks, in order to determine specific chemical markers for a selection of yellow dye plants. The second objective was to study the stability and degradation of dye molecules as a function of dyeing conditions, object conservation and the extraction methods used. Finally, the third objective was to apply the method developed to ancient objects and to see if it was possible to find some of the chemical markers described in the first two objectives.