Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells

Hee Shin,Makoto Shimizu,Mamoru Totsuka,Min-Jung Bae,Hideo Satsu

doi:10.3390/nu9020165

Abstract

Chlorogenic acid (CHA) and caffeic acid (CA) are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL)-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H2O2)-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK). Additionally, upstream of IKK, protein kinase D (PKD) was also suppressed. Finally, we found that they scavenged H2O2-induced reactive oxygen species (ROS) and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H2O2-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells.

Highlights

Chlorogenic acid (CHA) is one of the most widely consumed polyphenols because it occurs abundantly in numerous foods, especially coffee
CHA and caffeic acid (CA) inhibited activation of the protein kinase D (PKD)-IKK-NF-κB-IL-8 signaling pathway by scavenging intracellular reactive oxygen species (ROS) generated by oxidative stress
This study signaling pathway by scavenging intracellular ROS generated by oxidative stress

Summary

Introduction

Chlorogenic acid (CHA) is one of the most widely consumed polyphenols because it occurs abundantly in numerous foods, especially coffee. CHA has antioxidative [1], anti-inflammatory [2], anti-obesity [3], anti-diabetic [4], and anti-cancer activities [5] and owing to its biological effects, CHA has been used in various functional foods and as supplemental agents. CA is a phenolic acid that occurs naturally in numerous agricultural products such as fruits, vegetables, wine, olive oil, and coffee. Similar to CHA, CA has been reported to have antioxidant, Nutrients 2017, 9, 165; doi:10.3390/nu9020165 www.mdpi.com/journal/nutrients. We reported that oxidative stress-induced interleukin-8 (IL-8) secretion and mRNA expression were markedly inhibited by CHA

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Conclusion