. Conclusions
Curcumin dissolved in GS represents an option to prepare a
photostable and non-staining curcumin preparation which can be
“color-activated” upon addition of alcohol. GS is however, not suitable
as a vehicle in aPDT preparations of curcumin due to limited absorption
by the photosensitizer N310 nm. Curcumin (1.25 μM) dissolved in MC3
was highly phototoxic towards E. coli. However, MC3 leads to a
photolabile product and light protection should be considered. On the
other hand, MC3 was a more efficient solvent and stabilizer towards
curcumin hydrolysis than GS. It would be generally recommended to
store the products undiluted to avoid precipitation and hydrolysis of
curcumin. NADES are a new group of excipients with a potential in the
formulation of poorly soluble drugs. They seem to be particularly useful
in preparations intended for aPDT due to the ability to potentiate the PS
phototoxicity. Further, the ability of NADES to lock a molecule within
one specific molecular conformation was demonstrated.