Synthesis, characterization, and antioxidant properties of novel inulin derivatives with amino-pyridine group

A series of novel inulin derivatives were synthesized via reaction of chloracetyl inulin (CAR) with amino-pyridines, including 2-(2-amino-pyridyl)acetyl inulin chloride (2APAIL), 2-(3-amino-pyridyl)acetyl inulin chloride (3APAIL), 2-(4-amino-pyridyl)acetyl inulin chloride (4APAIL), 2-(2,3-diaminopyridyl)acetyl inulin chloride (2,3DAPAIL), and 2-(3,4-diamino-pyridyl)acetyl inulin (3,4DAPAIL). The antioxidant property of the products and 2-pyridylacetyl inulin chloride (PAIL) against hydroxyl radicals ((OH)-O-center dot), superoxide radicals (O-2(center dot)), and DPPH radicals (DPPH center dot) were evaluated in vitro, respectively. Results showed that 4APAIL and 3,4DAPAIL exhibited remarkable improvement on scavenging (OH)-O-center dot and DPPH center dot, which can scavenge the radical of (OH)-O-center dot completely at 0.4 mg/mL. Besides, the scavenging activity of 2,3DAPAIL to O-2(center dot) was excellent among all of the tested samples, reaching 85% at 1.6 mg/mL. These data indicate that all of the inulin derivatives have better antioxidant activities than inulin, and the scavenging effect indices are affected by the number and position of the amino group on pyridine grafted to the inulin derivatives. (C) 2014 Elsevier B.V. All rights reserved.