Maculosin is a host-specific phytotoxin for spotted knapweed from Alternaria alternata. Maculosin is a quorum-sensing molecule involved in cell-cell communication by Pseudomonas aeruginosa. Maculosin also acts as a signaling molecule regulating virulence gene expression in Lactobacillus reuteri. Maculosin shows antioxidant, anti-cancer and non-toxicity properties. Maculosin shows cytotoxic activity against the human liver cancer cell lines, with an IC50 of 48.90 µg/mL.