Anthocyanins from purple maize (Zea mays L.) downregulate lipopolysaccharide-induced peritonitis in mice by modulating the MyD88 signaling pathway

Background: Purple maize is a rich source of anthocyanins, known to exhibit bioactive health benefits. However, their potential anti-inflammatory activity is poorly known. Methods: Anthocyanin extracts (AE) from purple maize was characterized by LC-ESI-MS/MS platform. In vivo experimental model, AE (doses of 2 and 4 mg Antho/100 g body weight) was orally administered at two different times: 30 min before and 1 h after LPS intraperitoneal inflammatory stimulus. Peritoneal exudates were withdrawn 3 h after LPS injection, and leukocyte influx, cytokines and PGE2 were quantified. COX-2, TLR4, and MyD88 protein expression were evaluated by Western blotting. Results: Fourteen phenolic compounds were identified in AE, with cyanidin-3-O-glucoside and its acylated form as the major anthocyanins in both baths of purple maize extract evaluated. AE treatment significantly reduced leukocyte migration, mainly the polymorphonuclear leukocytes (p < 0.05) in the peritoneal exudates when administered 30 min and 1 h after LPS injection, at both doses. LPS-induced pro-inflammatory cytokines (IL-1 beta, IL-6, IL-10, KC, and CCL2) were inhibited (p < 0.05) by pre and posttreatments with AE (p < 0.05). Similarly, AE treatments suppressed LPS-induced COX-2 protein expression and decrease PGE2 levels in the peritoneal exudates (p < 0.05). Additionally, AE at the higher dose downregulated LPS-induced MyD88 expression (p < 0.05) when administered before and after LPS intraperitoneal injection. Under the experimental conditions, the constitutive expression of TLR4 in leukocytes was not modified. Conclusion: Our findings evidence for the first time that AE from purple maize provide preventive and antiinflammatory beneficial activity by downregulating key acute inflammatory components induced by LPS injection, by modulating MyD88 signaling pathways.