Radical-Scavenging Antioxidant Cyclic Dipeptides and Silk Fibroin Biomaterials

Abstract

Cyclic dipeptide (CDP) based radical-scavenging antioxidant molecules have been developed through structure–activity screening of rationally designed symmetric and asymmetric aromatic molecules. The antioxidant efficiencies of the designed CDPs were evaluated against the standard antioxidants ascorbic acid (natural) and butylated hydroxyanisole (a synthetic ingredient used in food, cosmetics, and medicine). Incorporation of the non-proteinogenic aromatic amino acid l-3,4-dihydroxyphenylalanine (DOPA) into the structure bestowed the CDPs with superior antioxidant properties. Detailed colorimetric antioxidant studies demonstrated the potential radical-scavenging properties of DOPA-containing CDPs. The non-cytotoxic nature of the antioxidant CDPs was established in murine adrenal PC12 cells. Antioxidant CDP-incorporated silk fibroin (CDP/SF) electrospun biomaterial scaffolds were prepared from their respective solutions. The CDP/SF biomaterial scaffolds exhibited excellent radical-scavenging properties highlighting their potential for therapeutic and tissue engineering applications. Overall, the present study highlights the radical-scavenging properties of antioxidant CDPs both in their molecular form and in their electrospun biomaterial scaffolds.