The limited bioavailability of the highly hydrophobic natural compound, curcumin with wide range of beneficial bioactivity is still a challenge. Self-association type systems of polyethylene oxide-polypropylene oxide-polyethylene oxide block copolymers (Pluronic) were applied to enhance the aqueous solubility of curcumin. Comparison of four Pluronics (94, 105, 127,108) with different compositions led to the conclusion that solubilization capacity is maximum for Pluronic 105 with intermediate polarity (hydrophilic/lipophilic balance (HLB) = 15) possessing the optimum balance between capacity of hydrophobic core of the micelle and hydrophilic stabilizing shell of the associate. Curcumin concentration in aqueous solution was managed to increase 105 times up to 1-3 g/L applying Pluronic at 0.01 mol/L. Formation of a host-guest complex of cyclodextrin as another way of increasing the curcumin solubility was also tested. Comparing the(2-hydroxypropyl)-α,β and γ cyclodextrins (CD) with 6, 7 and 8 sugar units and their polymers (poly-α-CD, poly-β-CD, poly-γ-CD)the γ-CD with the largest cavity found to be the most effective in curcumin encapsulation approaching the g/L range of concentration. The polymer type of the CDs presented prolonged and pH dependent release of curcumin in the gastrointestinal (GI) system modelled by simulated liquids. This retarding effect of polyCD was also shown and can be used for tuning in the combined system of Pluronic micelle and polyCD where the curcumin release was slower than from the micelle.
Bibliographical noteFunding Information:
Acknowledgments: The authors thank CsabaNémeth for his help in performing ATR FTIR measurements. This work was completed in the ELTE Institutional Excellence Program (1783-3/2018/FEKUTSTRAT) supported by the Hungarian Ministry of Human Capacities, and VEKOP-2.3.2-16-2017-00013 and -00014, OTKA K 115939, OTKA K 131594supported by National Research Development and Innovation Office, Hungary.
- Curcumin solubilization
- Cyclodextrin and polymeric cyclodextrin
- Pluronic micelle
- Release of curcumin from drug delivery system