Phenolic composition of orange peels and modulation of redox status and matrix metalloproteinase activities in primary (Caco-2) and metastatic (LoVo and LoVo/ADR) colon cancer cells

Orange (Citrus sinensis) peels, consumed in the diet as wines, candies or as infusions, are rich sources of phenolic compounds. This study sought to investigate the protective ability of phenolic extracts from orange peels against oxidative stress in primary human colonic tumor (Caco-2) and metastatic cell lines (LoVo and LoVo/ADR). The effects of the extracts on glutathione reductase, glutathione peroxidase and total matrix metalloproteinase (MMP) activities in the cells were also investigated. The results revealed that the extracts displayed cellular antioxidant activities and increased the activities of glutathione reductase and glutathione peroxidase in the cells. Furthermore, the extracts inhibited total MMP activities in the cells in a dose-dependent manner. HPLC fingerprinting revealed the presence of flavonoids and hydroxycinnamic acid. This study showed that orange peels phenolic extracts exhibited cellular antioxidant activity and inhibited MMP activity in colon cancer cells.