Enhanced solubility and antioxidant activity of chlorogenic acid-chitosan conjugates due to the conjugation of chitosan with chlorogenic acid

Abstract

Chlorogenic acid-chitosan conjugate was synthesized by introducing of chlorogenic acid onto chitosan with the aid of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and hydroxybenzotriazole. The data of UV-vis, FT-IR and NMR for chlorogenic acid-chitosan conjugates demonstrated the successful conjugation of chlorogenic acid with chitosan. Compared to chitosan, chlorogenic acid-chitosan conjugates exhibited increased solubility in distilled water, 1% acetic acid solution (v/v) or 50% ethanol solution (v/v) containing 0.5% acetic acid. Moreover, chlorogenic acid-chitosan conjugates showed dramatic enhancements in metal ion chelating activity, total antioxidant capacity, scavenging activities on 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) and superoxide radicals, inhibitory effects on lipid peroxidation and β-carotene-linoleic acid bleaching, and protective effect on H₂O₂-induced oxidative injury of PC12 cells. Particularly, chlorogenic acid-chitosan conjugate exhibited higher inhibitory effects on lipid peroxidation and β-carotene-linoleic acid bleaching than chlorogenic acid. The results suggested that chlorogenic acid-chitosan conjugates could serve as food supplements to enhance the function of foods in future.

Keywords: 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (PubChem CID: 15908); 2,2′-Azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid (ABTS) (PubChem CID: 5815211); 2,4,6-tris (2-pyridyl)-s-triazine (TPTZ) (PubChem CID: 77258); Antioxidant activity; Chitosan; Chitosan (PubChem CID: 71853); Chlorogenic acid; Chlorogenic acid (PubChem CID: 1794427); Folin-Ciocalteu reagent (PubChem CID: 452323); Hydroxybenzotriazole (PubChem CID: 75771); Nicotinamide adenine dinucleotide disodium salt (NADH) (PubChem CID: 2724710); Nitrotetrazolium blue chloride (NBT) (PubChem CID: 9281); Phenazine methosulfate (PMS) (PubChem CID: 9285); Polyphenol-chitosan conjugate; Solubility.