Antibacterial evaluation of natural oridonin and its chemically synthesised derivatives

Antimicrobial resistance has become one of the most important and pressing healthcare challenges of the present time [1]. Plant-derived natural antimicrobials have recently regained increased attention due to their great structural and chemical diversity [2] [3]. Isodon rubescens (Hemsl.) H.Hara is a perennial herb of the genus Isodon in the Labiatae family [4]. Isodon diterpenoids have attracted considerable attention as antibacterial, anti-inflammatory and anti-tumour agents. Oridonin, an ent-kaurane diterpenoid, has been attracting rising attention in recent years as the main bioactive chemical component of I. rubescens, and it is the material basis for its efficacy [5]. The aim of this study is to investigate the antibacterial activities of oridonin and four oridonin derivatives (X1, DCL-13, DCL-13p, C07-4BDXS) against Escherichia coli. Broth microdilution assay was used to determine the minimum inhibitory concentration (MIC) of each compound. Uptake of the florescent probe 1-N-phenylnaphthylamine (NPN) was applied to determine the permeability changes in the cell membrane of E. coli. Oridonin and its derivatives (X1 and C07-4BDXS) permeabilise the outer membrane of E. coli MG655 and DH5a pUC19 with inhibitory activity between 100 μM – 25 μM. DCL- 13 and DCL-13p have weaker antibacterial activity against E. coli growth, with MIC values≥200 μM, suggesting a weaker bacteriostatic effect. Our results represent a first step towards the potential application of oridonin and its synthetic derivatives in the prevention and treatment of bacterial infections.

 

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Publication History

Article published online:
16 November 2023