Relationship between Neuroprotective Effects and Structure of Procyanidins.

This study evaluated the relationship between the neuroprotective effects of procyanidins and their structural characteristics. In vitro, a rat pheochromocytoma cell line (PC12) was exposed to the grape seed-derived procyanidin monomers: catechin (C), epicatechin (EC), and epicatechin gallate (ECG); the procyanidin dimers: procyanidin B1 (B1), procyanidin B2 (B2), procyanidin B3 (B3), procyanidin B4 (B4), procyanidin B1-3--gallate (B1-G), and procyanidin B2-3--gallate (B2-G); and the procyanidin trimers: procyanidin C1 (C1) and -acetyl-l-cysteine (NAC) for 24 h. Cells were then incubated with 200 μM HO for 24 h. In vivo, zebrafish larvae (AB strain) 3 days post-fertilization were incubated with NAC or procyanidins (C, EC, ECG, B1, B2, B3, B4, B1-G, B2-G, C1) in 300 µM HO for 4 days. Different grape seed procyanidins increased the survival of PC12 cells challenged with HO, improved the movement behavior disorder of zebrafish caused by HO, inhibited the increase of ROS and MDA and the decrease of GSH-Px, CAT, and SOD activities, and up-regulated the Nrf2/ARE pathway. The neuroprotective effects of the procyanidin trimer C1 treatment group were greater than the other treatment groups. These results suggest that the neuroprotective effect of procyanidins is positively correlated with their degree of polymerization.