Phenanthrene Derivatives from Asarum heterotropoides Showed Excellent Antibacterial Activity against Phytopathogenic Bacteria

Xiaojing Fan 1 2 3, Dan Kong 1 2, Shan He 1 2, Junzheng Chen 1, Yue Jiang 1 2, Zhiqing Ma 1 2, Juntao Feng 1 2, He Yan 1 2

PMID: 34813299 DOI: 10.1021/acs.jafc.1c04385

Abstract

Asarum heterotropoides extracts showed strong antibacterial activity against selected phytopathogenic bacteria. Bioguided isolation was conducted to obtain 11 phenanthrene derivatives (1-11), 4 phenylpropanoids (12-15), a flavonoid (16), and a steroid (17), including a new phenanthrene derivative (1). In vitro bioassay results showed that phenanthrene derivatives are the main active components of A. heterotropoides extracts. The new compound aristoloxazine C (1) was found to exhibit outstanding antibacterial activity against Ralstonia solanacearum, Xanthomonas oryzae, Erwinia carolovora, Pseudomonas syringae, and Xanthomonas axonopodis, 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 (1) 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 (1) was primarily related to the destruction of the bacterial cell wall structure. Thus, aristoloxazine C (1) 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.

Keywords: Ralstonia solanacearum; antibacterial activity; aristoloxazine C; botanical bactericide; phytopathogenic bacteria.