Changes in chemical stability and bioactivities of curcumin by forming inclusion complexes of beta- and Gama-cyclodextrins

Abstract

In the present study investigated the effect of curcumin (CUR), beta (β) and gamma (γ) cyclodextrin (CD) complexes on its solubility, stability, antioxidating activity and bioavailability. CUR the active principle of turmeric is a natural antioxidant agent with potent anti-inflammatory activity along with chemotherapeutic and chemopreventive properties. Poor solubility and poor oral bioavailability are the main reasons which preclude CUR use in therapy. Curcumin/CD complex systems were prepared and characterized by FT-IR, UV-Vis and 1HNMR spectroscopies. The content, solubility, dissolution, and stability of the complexes were evaluated and compared with curcumin and their physical mixture. The phase solubility analysis indicated that the solubility of CUR was increased in the presence of CDs and revealed an A(L)-type diagram, suggesting the formation of a 1:1 inclusion complex. The estimated apparent stability constant (K1:1), according to the Higuchi and Connors method, is 1.87 × 105 M−1 and 5.99 × 105 M−1 for CUR/β-CD and CUR/γ-CD respectively. The results of this study confirm the formation of inclusion complexes in solution and suggest that the complexes formation between CUR and CDs could improve the bioavailability of the drug due to the enhancing absorption expected from increased drug solubility. Furthermore, the antioxidant activities of CUR and CDs inclusion complexes were determined by the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) method. The experimental results confirmed the forming of CUR complexes with CDs also these indicated that the CUR/CDs inclusion complexes were the most reactive than its free form into antioxidant activity.