Antibacterial Activity of Two New Cassane Diterpenoids from against by Damage to Cell Membrane.

, a Gram-positive bacterium, is a food contaminant that threatens the health of thousands of people around the world. Because of the continuous emergence of drug-resistant strains, the development of new classes of bactericides from natural products is of high priority. In this study, two novel cassane diterpenoids (pulchins A and B) and three known ones (-) were elucidated from the medicinal plant (L.) Sw. Pulchin A, with a rare "6/6/6/3" carbon skeleton, showed significant antibacterial activity against and , with MIC values of 3.13 and 6.25 μM, respectively. Further investigation of its mechanism of antibacterial activity against is also discussed in detail. The results revealed that the antibacterial activity of pulchin A against may be caused by pulchin A interfering with bacterial cell membrane proteins, affecting membrane permeability and causing cell damage or death. Thus, pulchin A may have a potential application as an antibacterial agent in the food and agricultural industries.