Glucose‐lysine Maillard reaction products fortified with caffeic acid potentiate anti‐oxidant and anti‐inflammatory properties in macrophages

The Maillard reaction (MR) occurs between reducing sugars and amino compounds during thermal processes of food. MR produces an array of MR products (MRPs) that promote food quality (i.e., color and flavor) and may increase anti‐oxidative, anti‐microbial, and anti‐hypertensive activities of food. Caffeic acid is one of the most widely consumed polyphenol abundant in fruits, vegetables, and coffee. It is well known that caffeic acid possesses strong antioxidant activity that may delay or prevent the prevalence of inflammatory diseases. However, no study has been conducted to determine whether MRPs fortified with caffeic acid (caffeic acid‐MRPs) possess higher anti‐oxidative and/or anti‐inflammatory potential than caffeic acid. The aim of this study is to compare anti‐oxidative and/or anti‐inflammatory properties of caffeic acid before and after MR using glucose and lysine model. Browning (A420), UV‐visible spectra, and antioxidant activities of caffeic acid and caffeic acid‐MRPs were evaluated while heating at 100°C for 0~12 h. Caffeic acid alone was unstable during heating compared to other cinnamic acid derivatives of cinnamic or coumaric acids. In contrast, caffeic acid‐MRPs enhanced browning and potentiated antioxidant activities of caffeic acid per se by DPPH and FRAP assay. More importantly, LPS‐mediated proinflammatory gene expression levels of IL‐6, IL‐8, and TNFα were significantly lower in caffeic acid‐MRPs treatment than caffeic acid alone in J774 macrophages. Consistently, caffeic acid‐MRPs incubation markedly attenuated the LPS‐induced ROS production and NF‐kβ activation in J774 cells. Moreover, pre‐incubation of caffeic acid‐MRPs significantly decreased caspase‐1 cleavage and IL‐1b secretion compared to caffeic acid in J774 macrophages. Collectively, these data suggest that caffeic acid‐MRPs not only promote browning but also potentiate anti‐inflammatory and anti‐oxidative properties of food. Fortification of caffeic acid during MR might be a useful approach to improve food qualities as well as nutritional values for food that requires thermal processing.