Effects of an aqueous extract of cocoa on nitric oxide production of macrophages activated by lipopolysaccharide and interferon-γ

Abstract 

Objective

Macrophages are the primary targets of bacterial lipopolysaccharide (LPS). The effects of cocoa extract on production of nitric oxide (NO) by murine J774.1 macrophages activated by LPS and interferon-γ (IFN-γ) were examined.

Methods

Cocoa was suspended in heated water and centrifuged, and the supernatant was then filtered. Nitrite was measured as a quantitative indicator of NO by spectrophotometry. LPS (1.0 mg/mL) and IFN-γ (100 U/mL) were added to cultured macrophages with 0.05% cocoa extract, 0.25% cocoa extract, or pure water. NO synthesis by macrophages was significantly inhibited by cocoa extract (P < 0.01).

Results

The inhibitory effect increased with concentration of the extract (P < 0.01). IFN-γ (100 U/mL) and, later, LPS (100 μg/mL) were added, together with 2.0% cocoa or pure water, to cultured macrophages. An inhibitory effect on NO production was observed on addition of only IFN-γ, but more significant effects were obtained with addition of LPS (P < 0.01) and addition of both was most effective (P < 0.01).

Conclusions

These data suggested that cocoa extract contains a suppressor of NO production in murine macrophages activated by LPS and IFN-γ. This effect does not appear to be caused merely by neutralization of LPS.

Keywords:  cocoa extract, Theobroma cacao, nitric oxide synthase inhibitor, macrophage, enteral nutrition, lipopolysaccharide