Nanostructured lipid carriers loaded with curcuminoids: Physicochemical characterization, in vitro release, ex vivo skin penetration, stability and antioxidant activity

Four formulations of nanostructured lipid carriers (NLC) loaded with curcuminoids where prepared, testing two types of solid lipids (Compritol (R) 888 ATO and Precirol (R) ATO 5) and two kinds of stabilizers (poloxamer 407 and polysorbate 80). Particle size values between 111 and 214 nm and polydispersity indices < 0.3 were registered, with low Z potential values due to the nonionic character of the stabilizers. The results showed that the type of surfactant had an impact on the in vitro release rate and on the ex vivo skin permeation capability of curcuminoids. Polysorbate 80 delayed the release, but favors the transport of a higher amount of curcuminoids to the receptor solution during the ex vivo permeation studies than the systems with poloxamer 407. Confocal microscopy confirmed that all systems favored the penetration of curcuminoids to deeper layers of the skin and in a greater amount than curcuminoids in solution. Exposure of the systems to intense radiation caused the degradation of curcuminoids, without loss of antioxidant activity, confirming that the degradation products also function as antioxidants. The NLC prepared can be valuable carriers to enhance the penetration of curcuminoids into the skin, to treat different disorders and skin diseases.