p-Hydroxycinnamic Acids: Advancements in Synthetic Biology, Emerging Regulatory Targets in Gut Microbiota Interactions, and Implications for Animal Health

p-hydroxycinnamic acids (p-HCAs), a class of natural phenolic acid compounds extracted from plant resources and widely distributed, feature a C6-C3 phenylpropanoid structure. Their antioxidant, anti-inflammatory, and antibacterial activities have shown great potential for applications in food and animal feed. The interactions between p-HCAs and the gut microbiota, as well as their subsequent effects on animal health, have increasingly attracted the attention of researchers. In the context of a greener and safer future, the progress and innovation in biosynthetic technology have occupied a central position in ensuring the safety of food and feed. This review emphasizes the complex mechanisms underlying the interactions between p-HCAs and the gut microbiota, providing a solid explanation for the remarkable bioactivities of p-HCAs and their subsequent impact on animal health. Furthermore, it explores the advancements in the synthetic biology of p-HCAs. This review could aid in a basis for better understanding the underlying interactions between p-HCAs and gut microbiota and animal health.