Abstract/Summary

This study hypothesized that the predominant strawberry anthocyanin, pelargonidin-3-O-glucoside (Pg-3-glc), and three of its plasma metabolites (4-hydroxybenzoic acid, protocatechuic acid and phloroglucinaldehyde [PGA]) would affect phagocytosis, oxidative burst and the production of selected pro- and anti-inflammatory cytokines in a whole blood culture model. For the assessment of phagocytosis and oxidative burst activity of monocytes and neutrophils, whole blood was pre-incubated in the presence or absence of the test compounds at concentrations up to 5 μM, followed by analysis of phagocytic and oxidative burst activity using commercially available test kits. For the cytokine analysis, diluted whole blood was stimulated with lipopolysaccharide in the presence or absence of the test compounds at concentrations up to 5 μM. Concentrations of selected cytokines (tumor necrosis factor-α [TNF-α], interleukin [IL]-1β, IL-6, IL-8 and IL-10) were determined using a cytometric bead array kit. There were no effects of any of the test compounds on phagocytosis of opsonized or non-opsonized E. coli or on oxidative burst activity. Pg-3-glc and PGA at 0.08 μM increased the concentration of IL-10 (P<0.01 and P<0.001, respectively), but there was no effect on TNF-α, IL-1β, IL-6 and IL-8 and there were no effects of the other compounds. In conclusion, this study demonstrated a lack of effect of these compounds on the opsonization, engulfment and subsequent destruction of bacteria. Pg-3-glc and PGA, at physiologically relevant concentrations, had anti-inflammatory properties; however, effects were modest, only observed at the lowest dose tested and limited to IL-10.