Phenanthrene Derivatives from Showed Excellent Antibacterial Activity against Phytopathogenic Bacteria.

extracts showed strong antibacterial activity against selected phytopathogenic bacteria. Bioguided isolation was conducted to obtain 11 phenanthrene derivatives (-), 4 phenylpropanoids (-), a flavonoid (), and a steroid (), including a new phenanthrene derivative (). bioassay results showed that phenanthrene derivatives are the main active components of extracts. The new compound aristoloxazine C () was found to exhibit outstanding antibacterial activity against , , , , and , with MIC values of 0.05, 2.5, 2.5, 5, and 6.25 μg/mL, respectively. These values were significantly higher than that of the positive control, streptomycin sulfate. Aristoloxazine C () also demonstrated an excellent control effect on tobacco bacterial wilt. Physiological and biochemical experiments combined with electron microscopy showed that the antibacterial activity of aristoloxazine C () was primarily related to the destruction of the bacterial cell wall structure. Thus, aristoloxazine C () may have the potential to be used as a template for the development of new bactericides or as a probe for the discovery of new antimicrobial targets.