Structural and therapeutic properties of curcumin solubilized pluronic F127 micellar solutions and hydrogels

Curcumin, the principle active constituent of turmeric, is known to have broad range of therapeutic properties. Its poor aqueous solubility and low bioavailability however, act as constraints for its biomedical applications. Recent studies have shown that incorporation of curcumin in nano-carriers like micelles, vesicles, polymeric nanoparticles etc. can help in overcoming these issues and improve its therapeutic abilities quite significantly. In this manuscript, we report preparation of curcumin solubilized pluronic F127 micellar solutions and hydrogels, along with their structural and therapeutic properties as obtained from SANS, rheological, anti-cancer and wound healing studies. Pluronic F127 being approved by FDA has been used quite extensively as excipient for drug delivery applications. Curcumin solubilization in the aqueous pluronic F127 system was carried out by briefly heating the copolymer solutions with curcumin at 90 °C. The concentrations of curcumin thus obtained were found to be comparable to those obtained by conventional methods of solubilization like thin film hydration or solvent evaporation method, and three orders of magnitude higher than that in pure water. SANS and rheological studies show that curcumin solubilization does not bring about any significant change in the structural and rheological properties of F127 micellar solutions and hydrogels. Curcumin solubilized F127 micellar solutions can be reconstituted after lyophilization, suggesting that curcumin remains nano-dispersed in lyophilized state. Micellar encapsulated curcumin exhibits very good stability in solution state in ambient condition but fails to show cytotoxicity against MCF7 cancer cells, presumably due to shielding of curcumin by large corona region of F127 micelles. Micellar curcumin containing F127 hydrogels on the other hand, exhibit wound healing abilities in mice model upon topical application. The results give an account of how some of the therapeutic properties of curcumin are manifested under micellar encapsulation and the role of pluronic F127 as excipient in those therapeutic applications.