Inhibitory activity of flavonoids fraction from Astragalus membranaceus Fisch. ex Bunge stems and leaves on Bacillus cereus and its separation and purification

Liyan Cui; Zhennan Ma; Wenhui Li; Haihui Ma; Shang Guo; Defu Wang; Yanbing Niu

doi:10.3389/fphar.2023.1183393

Inhibitory activity of flavonoids fraction from Astragalus membranaceus Fisch. ex Bunge stems and leaves on Bacillus cereus and its separation and purification

Front Pharmacol. 2023 Jul 3:14:1183393. doi: 10.3389/fphar.2023.1183393. eCollection 2023.

Authors

Liyan Cui¹, Zhennan Ma², Wenhui Li², Haihui Ma², Shang Guo³, Defu Wang², Yanbing Niu^{1

2}

Affiliations

¹ College of Grassland Science, Shanxi Agricultural University, Jinzhong, Shanxi, China.
² College of Life Sciences, Shanxi Agricultural University, Jinzhong, Shanxi, China.
³ Shanxi Institute for Functional Food, Shanxi Agricultural University, Taiyuan, Shanxi, China.

Abstract

Introduction: Astragalus membranaceus Fisch. ex Bunge is a traditional botanical drug with antibacterial, antioxidant, antiviral, and other biological activities. In the process of industrialization of A. membranaceus, most of the aboveground stems and leaves are discarded without resource utilization except for a small amount of low-value applications such as composting. This study explored the antibacterial activity of A. membranaceus stem and leaf extracts to evaluate its potential as a feed antibiotic substitute. Materials and methods: The antibacterial activity of the flavonoid, saponin, and polysaccharide fractions in A. membranaceus stems and leaves was evaluated by the disk diffusion method. The inhibitory activity of the flavonoid fraction from A. membranaceus stems and leaves on B. cereus was explored from the aspects of the growth curve, cell wall, cell membrane, biofilm, bacterial protein, and virulence factors. On this basis, the flavonoid fraction in A. membranaceus stems and leaves were isolated and purified by column chromatography to determine the main antibacterial components. Results: The flavonoid fraction in A. membranaceus stems and leaves had significant inhibitory activity against B. cereus, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were 1.5625 and 6.25 mg/mL, respectively. A. membranaceus stem and leaf flavonoid fraction can induce death of B. cereus in many ways, such as inhibiting growth, destroying cell wall and cell membrane integrity, inhibiting biofilm formation, inhibiting bacterial protein synthesis, and downregulating virulence factor expression. In addition, it was clear that the main flavonoid with antibacterial activity in A. membranaceus stems and leaves was isoliquiritigenin. Molecular docking showed that isoliquiritigenin could form a hydrogen bonding force with FtsZ. Conclusion: A. membranaceus stem and leaf flavonoid fractions had significant inhibitory activity against B. cereus, and the main chemical composition was isoliquiritigenin.

Keywords: A. membranaceus stems and leaves; B. cereus; antibacterial activity; flavonoids; molecular docking.

Grants and funding

This work was supported by the China Agriculture Research System of MOF and MARA (Grant Number CARS-21), the science and technology support project for ‘Special’ and ‘Excellent’ agricultural high quality development in Shanxi province (Grant Number TYGC-48), and the applied basic research program of Shanxi province (Grant Number 201801D221251).