Innovative techniques for the extraction and characterization of natural products for health applications

The aim of this doctoral project is to make significant contributions to the field of natural products research, particularly in the areas of bioactive compounds, metabolomics, and green extraction techniques. The work has been structured across three major sections, each addressing critical challenges and opportunities in natural products discovery and applications. In Section 1, the potential of natural triterpenoids, such as ursolic and oleanolic acids, to combat antimicrobial resistance was thoroughly investigated. By focusing on their ability to inhibit multidrug tolerance and biofilm formation. Results highlight the promising role of these compounds in overcoming one of the most pressing issues in modern healthcare: antimicrobial resistance. Additionally, a review about quorum sensing inhibitors (2019-2023) provided further knowledge into innovative approaches for disrupting microbial communication pathways, laying the groundwork for future therapeutic developments in this area. Section 2 extended the exploration of natural products to geographical characterization and the study of specific plant species. Through the chemical profiling of Italian propolis and secondary metabolites in Triticum durum (Desf.) and Rumex usambarensis (Dammer). Results of these studies demonstrated how regional and botanical origins contribute to the bioactive potential of natural products. The findings underline the importance of targeted and non-targeted metabolomic approaches in uncovering the therapeutic potential of plant-based substances, enhancing the use of natural products in health-related applications. Section 3 focused on advancements in green extraction technologies, particularly using Natural Deep Eutectic Solvents (NADES). The synthesis and characterization of 21 different NADES demonstrated their utility in optimizing the extraction process for natural products. Through a detailed physicochemical evaluation, including structural elucidation and stability assessments, this section established the suitability of NADES as eco-friendly solvents for metabolomics studies. The non-targeted metabolomics analysis of Melissa officinalis L. leaves further validated the application of NADES in natural product extraction, providing valuable discoveries into how tailored solvents can enhance both the extraction and characterization of bioactive compounds. The findings presented in this thesis have broader implications for both natural product research and the development of new therapeutic agents. By combining targeted and non-targeted metabolomic techniques with green extraction methods, this work not only contributes to a deeper understanding of natural compounds but also advances sustainable practices in natural product formulation. The research highlights the versatility of NADES as environmentally friendly solvents and offers a framework for future studies focused on natural product extraction, characterization, and application in health-related fields. This doctoral work underscores the significant potential of natural products in addressing global challenges such as antimicrobial resistance and promotes the use of innovative, eco-friendly extraction techniques. The interdisciplinary approach taken here opens new avenues for the development of natural products with enhanced bioactivity and sustainability, marking an important step forward in the field of natural product research.