Protocatechuic acid inhibits proliferation of human colon cancer cell line

Cancers of the digestive tract, in particular colorectal cancer (CRC), are amongst those most responsive to dietary modification. Several studies have shown that approximatively 75% of all sporadic cases of CRC are directly influenced by diet (1) and that dietary modification is a feasible strategy for reducing CRC risk (2). The frequent consumption of fresh fruit and vegetables is associated with a low incidence of cancer. This may be partly due to the presence of phenolic compounds with antioxidant properties (3). Protocatechuic acid (PCA), one of the major cyanidin glucoside (CyG) metabolites, shows an antioxidant effect. Studies on bioavailability of CyG demostrated that PCA is actually present in the plasma of the CyG-fed rat contributing in vivo to the antioxidant activity of CyG (1, 2). Many antioxidants have been investigated for their potential usefulness as cancer chemopreventive agents as they have been thought to suppress carcinogenesis mainly during the initiation phase because of theyr radical scavenger activity. This study evaluated the effects of PCA (1-50-100-250 M) on CaCo-2 cell line, (a continuous line of heterogeneous human epithelial colorectal adenocarcinoma cells) on several parameters such as: viability, LDH release, GSH content, ROS levels and annexin V. Results demonstrated that PCA caused a significant and dose-dependent decrease in cell viability consequent to an oxidative/antioxidant imbalance which leads to apoptotic or necrotic cell death depending on PCA concentration. These data also suggest that PCA may represent a useful tool in prevention and/or therapy of colon cancer.