Preparation of Acylated Anthocyanin and Its Thermal Degradation Properties and Antioxidant Activity

Abstract

Food-grade methyl cinnamate as an acyl donor was used to enzymatically acylate cyanidin-3-O-glucoside (C3G) under reduced pressure, which has the advantages of safety, high efficiency and single acylation product. After being purified by semi-preparative high-performance liquid chromatography (SP-HPLC), the acylation product was evaluated for its thermal stability and antioxidant activity. The results showed that the acylation rate was 80%, and the purity of the purified acylated C3G was as high as 98.3%. Mass spectral analysis showed that the acylated product was cyanidin-3-(6-cinnamoyl)-glucoside (C3(6C)G). Acylation modification significantly improved the lipid solubility and thermal stability of C3G. C3G and C3(6C)G had weaker scavenging capacity against 2,2-amino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation but similar 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity, ferric reducing and antioxidant power (FRAP) and hydroxyl radical scavenging capacity compared with vitamin C (VC) at the same concentration. At 200 μmol/L, the hydroxyl and DPPH radical scavenging capacity of C3(6C)G was significantly enhanced compared with C3G (P 0.05), which showed that cinnamyl modification did not impair the antioxidant capacity of anthocyanins, but instead improved the scavenging capacity against hydroxyl radicals.

Keywords

• acylation; anthocyanin; centaulin-3-o-glucoside; methyl cinnamate; lipase