Protective effects of non-extractable phenolics from strawberry against inflammation and colon cancer in vitro

Strawberry is a rich source of phenolics. However, most studies focused on extractable phenolics (EP) while neglecting non-extractable phenolics (NEP). The aim of this study was to characterize EP and NEP from strawberry (Fragaria × ananassa) and determine their anti-inflammatory and anti-colon cancer potentials in cell culture models. NEP contained flavonols, flavanols and phenolic acids that were released through alkaline hydrolysis. NEP dose-dependently inhibited lipopolysaccharides -induced NO production in RAW 264.7 macrophage. Western blotting showed that NEP reduced the expression levels of pro-inflammatory proteins such as iNOS and c-FOS, but increased the expression level of antioxidative protein, such as HO-1. Moreover, NEP markedly suppressed proliferation of human colon cancer HCT116 cells via inducing G2/M phase cell cycle arrest and apoptosis. Collectively, these findings illustrated preventive effects of strawberry NEP against inflammation and colon cancer, shedding light on potential contribution of NEP from strawberry as a health-promoting agent.