ANS

ANS (8-Anilino-1-naphthalenesulfonic acid) is a competitive inhibitor targeting thyroxine binding globulin (TBG) (Ki=2.09×10⁶ M^-1). ANS is used in radioimmunoassay by displacing bound triiodothyronine (T3) to improve detection sensitivity. ANS can block the protein binding site of T3 and release free T3 for antibody recognition. As a fluorescent probe, ANS can specifically bind to the hydrophobic region of proteins (such as membrane proteins) and monitor the dynamics of protein conformation through changes in fluorescent signals. It is widely used in biochemical research and antibacterial material development^[1][2]. In Vitro:Laccase-catalyzed oxidation: 8-Anilino-1-naphthalenesulfonic acid (ANS) (1-10 g/L; 24-96 h) was converted into a green antimicrobial dye (λ_max=420-440 nm) by Cerrena unicolor laccase, and ANS lost fluorescence and gains antimicrobial activity^[1].
Environmental toxicity:
ANS (0.019 mg/mL; 5 min) is more toxic (EC₅₀) to Vibrio fisheri bacteria than its oxidized product (0.067 mg/mL)^[1].
Cytotoxicity:
ANS (0.247-0.382 mg/mL; 24 h) inhibits the viability of colon epithelial cells and fibroblasts by LDH/MTT assay, and the oxidized product was less toxic (IC₅₀=0.321-0.473 mg/mL)^[1].
Antimicrobial activity:
ANS (0.025-0.4 mg/mL; 24 h) inhibits the growth of Staphylococcus aureus and Staphylococcus epidermidis (MIC=0.025-0.2 mg/mL), and the oxidized products showed a broader spectrum of bactericidal activity (MBC 0.1-1.0 mg/mL)^[1].
Antioxidant potential:
ANS (0.027-153 µg/mL) scavenges ABTS, DPPH, and hydroxyl radicals better than its oxidized products (IC₅₀=0.115-660 µg/mL)^[1].
Protein binding assay:
ANS (1-10 µM; 30 min) binds to the hydrophobic pockets of proteins (e.g., thyroxine-binding globulin) by fluorescence enhancement and was used to detect conformational changes^[2].