Cacao extracts suppress tryptophan degradation of mitogen-stimulated peripheral blood mononuclear cells

Ethnopharmacological relevanceThe fruits of Theobroma cacao L. (Sterculiaceae) have been used as food and a remedy for more than 4000 years. Today, about 100 therapeutic applications of cacao are described involving the gastrointestinal, nervous, cardiovascular and immune systems. Pro-inflammatory cytokine interferon-γ and related biochemical pathways like tryptophan degradation by indoleamine 2,3-dioxygenase and neopterin formation are closely associated with the pathogenesis of such disorders.Aim of the studyTo determine the anti-inflammatory effect of cacao extracts on interferon-γ and biochemical consequences in immunocompetent cells.Materials and methodsEffects of aqueous or ethanolic extracts of cacao were examined on mitogen-induced human peripheral blood mononuclear cells (PBMC) of healthy donors and on lipopolysaccharide-stimulated myelomonocytic THP-1 cells. Antioxidant activity of extracts was determined by oxygen radical absorption capacity (ORAC) assay.ResultsIn mitogen-stimulated PBMC, enhanced degradation of tryptophan, formation of neopterin and interferon-γ were almost completely suppressed by the cacao extracts at doses of ≥5 μg/mL. Cacao extracts had no effect on tryptophan degradation in lipopolysaccharide-stimulated THP-1 cells.ConclusionsThere is a significant suppressive effect of cacao extracts on pro-inflammatory pathways in activated T-cells. Particularly the influence on indoleamine 2,3-dioxygenase could relate to some of the beneficial health effects ascribed to cacao.