Release-Modulated Antioxidant Activity of a Composite Curcumin-Chitosan Polymer

Martin G. O'Toole, Patricia A. Soucy, Rajat Chauhan, Mandapati V Ramakrishnam Raju, Dhruvina N. Patel, Betty M. Nunn, Megan A. Keynton, William D. Ehringer, Michael H. Nantz, Robert S. Keynton, Andrea S. Gobin

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

Curcumin is known to have immense therapeutic potential but is hindered by poor solubility and rapid degradation in solution. To overcome these shortcomings, curcumin has been conjugated to chitosan through a pendant glutaric anhydride linker using amide bond coupling chemistry. The hybrid polymer has been characterized by UV-visible, fluorescence, and infrared spectroscopies as well as zeta potential measurements and SEM imaging. The conjugation reactivity was confirmed through gel permeation chromatography and quantification of unconjugated curcumin. An analogous reaction of curcumin with glucosamine, a small molecule analogue for chitosan, was performed and the purified product characterized by mass spectrometry, UV-visible, fluorescence, and infrared spectroscopies. Conjugation of curcumin to chitosan has greatly improved curcumin aqueous solubility and stability, with no significant curcumin degradation detected after one month in solution. The absorbance and fluorescence properties of curcumin are minimally perturbed (λmax shifts of 2 and 5 nm, respectively) by the conjugation reaction. This conjugation strategy required use of one out of two curcumin phenols (one of the main antioxidant functional groups) for covalent linkage to chitosan, thus temporarily attenuating its antioxidant capacity. Hydrolysis-based release of curcumin from the polymer, however, is accompanied by full restoration of curcumin's antioxidant potential. Antioxidant assays show that curcumin radical scavenging potential is reduced by 40% after conjugation, but that full antioxidant potential is restored upon hydrolytic release from chitosan. Release studies show that curcumin is released over 19 days from the polymer and maintains a concentration of 0.23 ± 0.12 μM curcumin/mg polymer/mL solution based on 1% curcumin loading on the polymer. Release studies in the presence of carbonic anhydrase, an enzyme with known phenolic esterase activity, show no significant difference from nonenzymatic release studies, implying that simple ester hydrolysis is the dominant release mechanism. Conjugation of curcumin to chitosan through a phenol ester modification provides improved stability and solubility to curcumin, with ester hydrolysis restoring the full antioxidant potential of curcumin.

Original languageEnglish (US)
Pages (from-to)1253-1260
Number of pages8
JournalBiomacromolecules
Volume17
Issue number4
DOIs
StatePublished - Apr 11 2016
Externally publishedYes

Fingerprint

Curcumin
Chitosan
Antioxidants
Polymers
Composite materials
Hydrolysis
Esters
Solubility
Fluorescence spectroscopy
Phenols
Infrared spectroscopy
Carbonic anhydrase
Glucosamine
Degradation
Scavenging
Gel permeation chromatography
Zeta potential
Polymer solutions
Amides
Functional groups

ASJC Scopus subject areas

  • Bioengineering
  • Materials Chemistry
  • Polymers and Plastics
  • Biomaterials

Cite this

O'Toole, M. G., Soucy, P. A., Chauhan, R., Raju, M. V. R., Patel, D. N., Nunn, B. M., ... Gobin, A. S. (2016). Release-Modulated Antioxidant Activity of a Composite Curcumin-Chitosan Polymer. Biomacromolecules, 17(4), 1253-1260. https://doi.org/10.1021/acs.biomac.5b01019

Release-Modulated Antioxidant Activity of a Composite Curcumin-Chitosan Polymer. / O'Toole, Martin G.; Soucy, Patricia A.; Chauhan, Rajat; Raju, Mandapati V Ramakrishnam; Patel, Dhruvina N.; Nunn, Betty M.; Keynton, Megan A.; Ehringer, William D.; Nantz, Michael H.; Keynton, Robert S.; Gobin, Andrea S.

In: Biomacromolecules, Vol. 17, No. 4, 11.04.2016, p. 1253-1260.

Research output: Contribution to journalArticle

O'Toole, MG, Soucy, PA, Chauhan, R, Raju, MVR, Patel, DN, Nunn, BM, Keynton, MA, Ehringer, WD, Nantz, MH, Keynton, RS & Gobin, AS 2016, 'Release-Modulated Antioxidant Activity of a Composite Curcumin-Chitosan Polymer', Biomacromolecules, vol. 17, no. 4, pp. 1253-1260. https://doi.org/10.1021/acs.biomac.5b01019
O'Toole MG, Soucy PA, Chauhan R, Raju MVR, Patel DN, Nunn BM et al. Release-Modulated Antioxidant Activity of a Composite Curcumin-Chitosan Polymer. Biomacromolecules. 2016 Apr 11;17(4):1253-1260. https://doi.org/10.1021/acs.biomac.5b01019
O'Toole, Martin G. ; Soucy, Patricia A. ; Chauhan, Rajat ; Raju, Mandapati V Ramakrishnam ; Patel, Dhruvina N. ; Nunn, Betty M. ; Keynton, Megan A. ; Ehringer, William D. ; Nantz, Michael H. ; Keynton, Robert S. ; Gobin, Andrea S. / Release-Modulated Antioxidant Activity of a Composite Curcumin-Chitosan Polymer. In: Biomacromolecules. 2016 ; Vol. 17, No. 4. pp. 1253-1260.
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