6533b7ddfe1ef96bd1274556

RESEARCH PRODUCT

Valorization of natural drug products : from extraction to encapsulation

subject

description

This thesis was carried out at the Laboratory of Pharmacognosy and the Laboratory of Pharmaceutical technology, at the UFR Sciences de Santé, circonscription Pharmacy, in the University of Burgundy Franche-Comté, to find new natural molecules to encapsulate. First of all, we focused on the natural saponins from plants of the Vietnam biodiversity and the french horticulture, belonging to the three genera Dracaena, Cordyline (Asparagaceae) and Weigela (Caprifoliaceae). The work led to the successful isolation and elucidation of 42 natural saponins using various chromatographic techniques. The structures were determined by ESI mass spectrometry and NMR spectroscopy. Among the 17 pure compounds obtained from three species of the Weigela genus, 9 oleanolic acid and hederagenin glycosides are previously undescribed ones. From the two species Dracaena braunii and Cordyline fruticosa “Fairchild red”, we isolated and characterized 18 steroidal saponins including 7 new spirostane-types and 6 new furostane-types ones. The cytotoxic activities of the majority of isolated saponins were evaluated against mouse colon cancer (CT26 cells), mouse melanoma (B16 cells) and human liver cancer (HepG2 cells) by MTS assays. The structure / activity relationships were also proposed.On the other hand, we selected a well-known natural molecule to develop encaspulation tests. Among the natural products, curcumin has very interesting therapeutic properties but exhibits both a poor solubility and a low bioavailability, limiting the administration by the oral route. The purpose of this study was to improve the solubility and bioavailability of curcumin as well as simultaneously achieve controlled release in gastrointestinal tract. Pectinate gel beads were prepared based on ionotropic gelation method with the presence of vaious surfactants. After drying, these beads were investigated for physicochemical characteristics (morphological aspects, encapsulation efficiency, stability, physical state) and dissolution kinetics (in vitro release). Antioxidant activity was also determined with DPPH assay. Kolliphor HS15® seems to be the best promising surfactant to increase stability and bioavailability of curcumin.