Antibacterial Activity of Rosmarinic Acid Against Streptococcus agalactiae and Its Anti-Inflammatory Effects in Mouse Mastitis

Abstract

Simple Summary Mastitis is a prevalent and severe disease that hinders the development of the dairy industry. Improper use of antibiotics in dairy farms frequently promotes pathogen resistance, posing significant risks to animal production and food safety. Consequently, the development of natural, environmentally friendly antibacterial and anti-inflammatory alternatives is of high practical importance. Rosmarinic acid (RA), a natural plant extract, exhibits potential antibacterial and anti-inflammatory activities. This study evaluated the antibacterial and anti-inflammatory effects of RA against Streptococcus agalactiae (S. agalactiae) using bacterial assays and a mouse model of mastitis. Bacterial assays indicated that RA inhibited virulence factor expression and biofilm formation in S. agalactiae. Mouse mastitis experiments revealed that RA alleviated mammary inflammation by modulating the TLR2/NF-κB and PI3K/AKT signaling pathways. In conclusion, RA suppresses the growth of S. agalactiae and attenuates S. agalactiae-induced mouse mastitis. These findings provide a theoretical foundation for the development of novel green therapeutic strategies against mastitis and offer insights for sustainable livestock production.