AUTHOR=Liu Xi-Wang , Yang Ya-Jun , Qin Zhe , Li Shi-Hong , Bai Li-Xia , Ge Wen-Bo , Li Jian-Yong 

TITLE=Isobavachalcone From Cullen corylifolium Presents Significant Antibacterial Activity Against Clostridium difficile Through Disruption of the Cell Membrane

JOURNAL=Frontiers in Pharmacology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2022.914188

DOI=10.3389/fphar.2022.914188

ISSN=1663-9812

ABSTRACT=<p><bold>Background:</bold><italic>Clostridium difficile</italic> infection (CDI) has been widely reported in human and animals around the world over the past few decades. The high relapse rate and increasing drug resistance of CDI make the discovery of new agents against <italic>C. difficile</italic> fairly urgent. This study aims to investigate the antibacterial activity against <italic>C. difficile</italic> from traditional Chinese herb medicine <italic>Cullen corylifolium</italic> and confirm its active components.</p><p><bold>Methods:</bold> Phenolic extract from the seeds of <italic>C. corylifolium</italic> was prepared routinely and the contents of relative flavonoids were determined by High Performance Liquid Chromatography (HPLC). <italic>In vitro</italic> antibacterial activities of the phenolic extract and its major components were tested. The influence of the major components on cell membrane was investigated with membrane integrity by SEM and propidium iodid uptake assay. Cytotoxicity of the extract and its active compounds on Caco-2 cell line was assessed by CCK-8 kit. The <italic>in vivo</italic> therapeutic efficacy of IBCL was evaluated on the mice model.</p><p><bold>Results:</bold> Phenolic extract was found to be active against <italic>C. difficile</italic> with minimum inhibitory concentrations (MIC) of 8 μg/mL. As the major component of the extract, IBCL was the most active compound against <italic>C. difficile</italic>. The MIC of IBCL and 4MBCL were 4 μg/ml and 4 μg/ml, respectively. Meanwhile, PFPE, IBCL, and 4MBCL showed rapid bactericidal effect against <italic>C. difficile</italic> in 1 h, which was significant compared to antibiotic vancomycin. Mechanism studies revealed that IBCL can disrupt the integrity of the cell membrane, which may lead to the death of bacteria. PFPE was low cytotoxic against Caco-2 cells, and the cytotoxicity of IBCL and 4MBCL were moderate. Symptoms of CDI were effectively alleviated by IBCL on the mice model and weight loss was reduced. From death rates, IBCL showed better efficacy compared to vancomycin at 50 mg/kg dosage.</p><p><bold>Conclusion:</bold> As the major component of phenolic extract of <italic>C. corylifolium</italic> seeds, IBCL showed significant antibacterial activity against <italic>C. difficile in vitro</italic> and rapidly killed the bacteria by disrupting the integrity of the cell membrane. IBCL can significantly prevent weight loss and reduce death caused by CDI on the mice model. Therefore, IBCL may be a promising lead compound or drug candidate for CDI.</p>