“Click chemistry” based conjugation of lipophilic curcumin to hydrophilic ε-polylysine for enhanced functionality

• Published in: Food research international Vol. 54; no. 1; pp. 44 - 47
• Main Authors: Tikekar, Rohan V., Hernandez, Mateo, Land, Donald P., Nitin, N.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.11.2013; Elsevier
• Subjects: Antioxidants; Assaying; Bio-compatible polymer; Biological and medical sciences; Biopolymers; Click chemistry; Conjugates; Conjugation; Curcumin; Food industries; functional properties; Fundamental and applied biological sciences. Psychology; hydrophobicity; Infrared; oxygen radical absorbance capacity; Polymer conjugates; Spectra; spectroscopy; Triazoles; Curcumin; Click chemistry; Polymer conjugates; Bio-compatible polymer; Chemistry; Functionality; Polymer; Conjugation
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2013.06.004

This short communication demonstrates an application of “click chemistry” to conjugate small hydrophobic bioactive molecule such as curcumin with water soluble biopolymer such as ε-polylysine to improve the functionality of the biopolymer. ε-Polylysine and curcumin were modified to ε-polylysine azide and monoalkyne curcumin, respectively. The Huisgen cycloaddition (“click chemistry”) between the azide group and monoalkyne group led to formation of a triazole linkage between ε-polylysine and curcumin. The conjugation process was characterized using Fourier transform infrared (FT-IR) spectroscopy. Retention of functional activity of conjugated curcumin was evaluated by comparing the antioxidant activity of conjugates with native ε-polylysine using the oxygen radical absorbance capacity (ORAC) assay. FT-IR spectra showed a significant decrease in the peak intensity of azide group of ε-polylysine (2102cm−1) and a concomitant presence of triazole peak (1459cm−1) after reaction with monoalkyne curcumin, validating that conjugation was successful. ORAC assay showed that the antioxidant activity of ε-polylysine–curcumin conjugate was 3.6 fold higher than control ε-polylysine indicating that conjugated curcumin retained its functional properties. These results highlight the success of “click chemistry” to achieve conjugation of small molecules to polymers. •Curcumin was conjugated to ε-polylysine using copper catalyzed “click chemistry”.•The success of conjugation process was confirmed by FT-IR spectroscopy.•Conjugation resulted in increase in the antioxidant activity of the polymer.•“Click chemistry” based approach can be used to enhance functionality of polymers.