Acute inflammation is the fastest immune system response to damage. Normally, short-lasting and limited inflammation develops beneficial effects. However, permanent inflammation becomes harmful and painful. Carrageenin-induced paw oedema is a reproducible acute inflammatory model used in the screening of anti-inflammatory drugs. Cocoa, a product from Theobroma cocoa seeds, contains flavonoids with potential anti-inflammatory properties. Previous studies have shown that in vitro cocoa extract inhibits some pro-inflammatory cytokines (TNFα, monocyte chemotactic protein 1 (MCP-1) and IL-6)(1). The aim of the present study was to establish the in vivo anti-inflammatory effect of cocoa. Female Wistar rats (Harlan Iberica SA, Barcelona, Spain) received water (reference animals; n 10), quercetin (3.1 g/kg body weight orally; n 10) or cocoa at doses of 4.6 (n 10) or 9.6 (n 10) g/kg body weight orally for 7 d. On day 8 some reference animals were injected with quercetin (10 mg/kg rat intraperitoneally (ip)). After 1 h all animals were injected with 0.1 ml carrageenin λ (1%, w/v) into subplantar area of the right hind paw. Paw volume was measured by plethysmometry at 30 min post carrageenin injection and every hour for 6 h. Peritoneal macrophages (PM) and paw inflammatory exudates were obtained at the end of the study. PM were stimulated with lipopolysaccharide (LPS; 10 μg/ml) and supernatant fractions were obtained after 24 h incubation. TNFα levels in exudates and supernatant fractions were determined by an ELISA technique. A significant reduction in paw oedema (P<0.05) was observed in both groups treated with cocoa from 4 h after carrageenin injection (Figure). At 6 h paw volumes from cocoa-treated animals were about 35% lower than that of the reference group. Quercetin treatment did not modify paw volume. TNFα levels in paw inflammatory exudates were lower in animals treated with the highest cocoa dose (Table). However, TNFα secreted by PM was reduced in the group treated with 4.6 g cocoa/kg and in animals injected with quercetin ip. In summary, a cocoa-rich diet could play a role as an anti-inflammatory adjuvant. This immunomodulatory action can be partially attributed to a reduction in cytokine release by pro-inflammatory cells such as macrophages.
Mean values were significantly different from those for the reference group: *P<0.05, **P<0.001.