Plant extracts of spices and coffee synergistically dampen nuclear factor-κB in U937 cells.
A large array of bioactive plant compounds (phytochemicals) has been identified and synergy among these compounds might contribute to the beneficial effects of plant foods. The transcription factor nuclear factor-κB (NF-κB) has been suggested as a target for many phytochemicals. Due to the complexity of mechanisms involved in NF-κB regulation, including numerous feedback loops, and the large number of phytochemicals which regulate NF-κB activity, we hypothesize that synergistic or antagonistic effects are involved. The objectives of our study were to develop a statistical methodology to evaluate the concept of synergy and antagonism and to use this methodology in a monocytic cell line (U937 expressing an NF-κB-luciferase reporter) treated with lipopolysaccharide and phytochemical-rich plant extracts. Both synergistic and antagonistic effects were clearly observed. Observed synergy was most pronounced for the combinations of oregano and coffee, and thyme and oregano. For oregano and coffee the synergistic effect was highest at 5 mg/mL with 13.9% (P < .001), and for thyme and oregano the highest synergistic effects was at 3 mg/mL with 13.7% (P < .001). Dose dependent synergistic and antagonistic effects were observed for all combinations tested. In conclusion, this work presents a methodological tool to define synergy in experimental studies. Our results support the hypothesis that phytochemical-rich plants may exert synergistic and antagonistic effects on NF-κB regulation. Such complex mechanistic interactions between phytochemicals are likely to underlie the protective effects of a plant-based diet on life-style related diseases.
Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, 0317 Oslo, Norway.
Marit
M
Kolberg
Ingvild
I
Paur
Trude R
TR
Balstad
Sigrid
S
Pedersen
David R
DR
Jacobs
Rune
R
Blomhoff
D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D040503:Coffea / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D006801:Humans; D008070:Lipopolysaccharides / Q000494:pharmacology; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D031341:Origanum / Q000737:chemistry*; D064209:Phytochemicals / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D017365:Spices; D046930:Thymus Plant / Q000737:chemistry*; D020298:U937 Cells
D000893:Anti-Inflammatory Agents; D008070:Lipopolysaccharides; D016328:NF-kappa B; D064209:Phytochemicals; D010936:Plant Extracts
ANOVA; Food interactions; Inflammation; IκB; LPS; Methods; NF-κB; Phytochemicals; S-shaped; Sigmoid-shaped; Synergy; U937; analysis of variance; inhibitor of κB; lipopolysaccharide; luc; luciferase; nuclear factor–κB