Gastrodin Inhibits Bacterial Biofilm Formation, Thereby Activating the Antibacterial Activity of Antibiotics

(1) Background: The increasing antibiotic resistance of pathogens is necessitating new therapies that target virulence factors. Virulence factors include biofilm formation, which is a key pathogenic factor involved in bacterial pathogenicity and resistance. (2) Methods: Initially, biofilm formation assays were performed to screen the biofilm formation inhibition effects of gastrodin. A bacterial growth assay was performed to examine the synergistic effects and qRT-PCR was performed to identify the underlying molecular regulatory mechanisms. (3) Results: Gastrodin inhibits biofilm formation by bacteria such as E. faecalis (IC₅₀ = 1.56 μg/mL), E. faecium (IC₅₀ = 0.19 μg/mL), S. aureus (IC₅₀ = 6.25 μg/mL), C. acnes (IC₅₀ = 0.78 μg/mL), S. sobrinus (IC₅₀ = 12.5 μg/mL), P. aeruginosa (IC₅₀ = 25.00 μg/mL), and E. coli (IC₅₀ = 25. 10 μg/mL) without directly affecting bacterial growth, as shown by bacterial growth assay. Gastrodin also reduced the expression of cytolysin genes (cylLS, cylR2, and cylM), quorum sensing genes (fsrB, fsrC, gelE, ebpA, ebpB, acm, scm, and bps) and biofilm virulence genes (esp) as shown by qRT-PCR analysis and exhibited dramatic synergistic antibacterial effects in the growth assay. (4) Conclusions: These results suggest that gastrodin may be a promising novel antibacterial adjuvant for biofilm-related bacterial infections, but further experiments, including in vivo assays, are still needed.