Isolation and Identification of procyanidins in Aronia Melanocarpa Using NMR, LC-IT-TOF/MS/MS and MALDI-TOF MS

Abstract

Aronia melanocarpa berries procyanidins (Amps) were divided in three fractions: ethyl acetate phase extract of Amps (E-Amps), aqueous phase extract of Amps (W-Amps), and methanol phase extract of Amps (M-Amps). Flavan-3-ol monomers and oligomeric procyanidins were isolated from E-Amps using Sephadex LH-20 column chromatography and reversed-phase preparative HPLC. H and C NMR analyses indicated five flavan-3-ol monomers and oligomeric procyanidins: (+)catechin, (‒)epicatechin, procyanidin B2 [EC-(4β→8)-EC], procyanidin B1 [EC-(4β→8)-C], and procyanidin C1 [EC-(4β→8)-EC-(4β→8)-EC]. MALDI-TOF-MS analysis demonstrated that the structure units of polymeric Amps, which were linked by B-type bonds, contained only catechin and epicatechin. In addition, the degree of polymerization was from pentamer to twenty-two polymer. Five flavan-3-ol monomers and oligomeric procyanidins had strong antioxidant activities. The DPPH and ABTS free-radical scavenging capacities followed the order: flavan-3-ol monomers > dimeric procyanidins > trimeric procyanidins > ascorbic acid. However, FRAP values increased with a degree of polymerization.