In Vitro: Thonningianin B shows strong scavenging action against the DPPH radical. The DPPH radical is scavenged completely by a 34.5 µM solution of Thonningianin B. In a separate experiment, an IC50 value of Thonningianin B is determined to be 21 μM. Thonningianin B (0-100 μM; 24 h) inhibits BV-2 cell viability with an IC50 of 46.74 μM. Thonningianin B (10 μM; 24 h) significantly improves the ratio of LC3-II/LC3-I and the average number of GFP-LC3 puncta per cell in BV-2 cells.