The solubility of the scarcely water-soluble molecule tetrahydrocurcumin (THC), a promising curcumin derivative to be used as biopesticide, was enhanced through the formation of inclusion complexes with different CDs. Randomly methylated β-cyclodextrin (CRYSMEB, Roquette) gave the best results . Differential scanning calorimetry as well as 1H- and 2D-Nuclear Magnetic Resonance (NMR) proved the inclusion of THC in MeβCD. Rotating-frame Overhauser effect spectroscopy NMR especially illustrated specific interactions of aromatic protons of THC and protons located inside the CD cavity. The complex formation between THC and MeβCD was studied using the Higuchi and Connor method, giving an association constant of 591 M−1. THC-loaded CRYSMEB did not show any growth inhibition of the target fungus Fusarium graminearum. However, THC-loaded CRYSMEB polymers prepared by crosslinking with citric acid exhibited 25 % inhibition of the fungal growth, thus making them promising material for solvent-free, aqueous and bio-based fungicide formulations.
Fusarium graminearum can infect cereals such as maize, wheat or barley, leading to yield decreases up to 50 % by the potential production of mycotoxins it can cause health problems to humans and animals.
Anne Loron, Christian Gardrat, Nicolas Tabary, Bernard Martel, Véronique Coma (2021) Tetrahydrocurcumin encapsulation in cyclodextrins for water solubility improvement: synthesis, characterization and antifungal activity as a new biofungicide. Carbohydrate Polymer Technologies and Applications, 100113, https://doi.org/10.1016/j.carpta.2021.100113.