Preparation of curcuminoid niosomes for enhancement of skin permeation

Curcuminoids (curcumin, desmethoxycurcumin, and bisdesmethoxycurcumin) are major bioactive substances found in turmeric (Curcuma longa L.) extracts and possess antioxidant, anti-inflammatory, antimicrobial and anticancer properties. In this study, curcuminoid niosomes prepared with a series of Span non-ionic surfactants were developed to enhance the skin permeation of curcuminoids. Formulations were evaluated based on aggregation of niosomes, curcuminoid loading, % entrapment efficiency and in vitro permeation of curcuminoids through shed snake skin. Optimal formulations of curcuminoid niosomes including sorbitan monooleate, cholesterol, and Solulan C-24 at a mole ratio of 47.5:47.5:5 were obtained. Up to 11 micromoles of curcuminoids could be loaded in the niosome with a % entrapment efficiency of 83%. About 90% of the niosomes had a diameter of 12.25 +/- 5.00 microm. The niosomes significantly enhanced permeation of curcuminoids compared with a methanolic solution of curcuminoids: 4% of entrapped curcuminoids traversed the shed snake skin, whereas permeation from the methanolic solution was undetectable. The fluxes of curcumin, desmethoxycurcumin, and bisdesmethoxycurcumin were 1.117, 0.263, and 0.057 microg/(cm2h), respectively, consistent with the relative hydrophobicity of curcumin > desmethoxycurcumin > bisdesmethoxycurcumin. In conclusion, our data show that curcuminoids can be successfully formulated as niosomes and that such formulations have improved properties for transdermal delivery.