Synthesis of antioxidant polymers by grafting of gallic acid and catechin on gelatin.
A novel, simple, and cheap method to synthesize antioxidant-protein conjugates by grafting reaction was developed employing a hydrogen peroxide-ascorbic acid pair as radical initiator system. Our challenge was to covalently bind molecules with tested antioxidant activity, as gallic acid (GA) and catechin (CT) to a biomacromolecule, as gelatin, extensively used in the pharmaceutical, cosmetic, and food industry. In this way, two gelatin conjugates, bearing GA and CT covalently bounded to a side chain of protein, were synthesized. Calorimetric, UV-vis, and fluorescence analyses were performed to verify the covalent bond between antioxidant molecules and gelatin, and the antioxidant activity of conjugates was compared to that of a control polymer submitted to the same reaction conditions without antioxidant molecule. The ability of synthesized materials to inhibit 2,2'-diphenyl-1-picrylhydrazyl, hydroxyl radicals, and linoneic acid peroxidation was determined and, to well characterized antioxidant properties of grafted biomacromolecules, disposable phenolic equivalents and total antioxidant activity were calculated. The conjugates showed a good antioxidant activity, confirming the efficiency of the synthetic strategy proposed in this paper. The results clearly showed that antioxidant moieties covalently bounded to a natural polymer allow to introduce in the macromolecule peculiar features for specific industrial applications.
Dipartimento di Scienze Farmaceutiche, Università della Calabria, Edificio Polifunzionale, Arcavacata di Rende (CS) 87036, Italia.
Umile Gianfranco
UG
Spizzirri
Francesca
F
Iemma
Francesco
F
Puoci
Giuseppe
G
Cirillo
Manuela
M
Curcio
Ortensia Ilaria
OI
Parisi
Nevio
N
Picci
D000975:Antioxidants / Q000138:chemical synthesis*; D002392:Catechin / Q000737:chemistry*; D002617:Chemical Industry / Q000379:methods; D005707:Gallic Acid / Q000737:chemistry*; D005780:Gelatin / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis*
D000975:Antioxidants; D011108:Polymers; D005707:Gallic Acid; D002392:Catechin; D005780:Gelatin