Journal Of
Polyphenols

Abstract: Abstract A novel degradation method was investigated to synthesize highly biologically active flavan-3-ol derivatives in the presence of N-acetyl-L-cysteine (NAC) as a nucleophile under acidic conditions for polymerized proanthocyanidins degradation. The reaction conditions were optimized by the combination of single-factor test and central composite experimental design (CCD). Grape seed proanthocyanidins were reacted with NAC at a ratio of 1 : 3 with 0.3 M methanolic HCl, a temperature of 55 ºC, and a reaction time of 50 mins. M ost of the degradation products were separated and prepared by one-step high-speed countercurrent chromatography (HSCCC) and preparative high-performance liquid chromatography (prep-HPLC). Three monomeric proanthocyanidins and four new N-acetyl-L-cysteine derivatives were isolated from degradation products with total degradation yield of 55.44% and high purity over 95%. Furthermore, the neuroprotective abilities of these compounds to H2O2-treated PC-12 neuroblastoma cells were evaluated. NAC derivatives showed better antioxidant activity than their corresponding underivatized monomers and NAC, indicating that they had a better performance in protecting PC-12 cells from oxidative stress damage.

Key words: N-acetyl-L-cysteine, proanthocyanidins, HSCCC, antioxidant activity