Antibacterial evaluation of natural oridonin and its chemically synthesized derivatives

Antimicrobial resistance has become one of the most important and pressing healthcare challenges of the present time. Plant-derived natural antimicrobials have recently regained increased attention due to their great structural and chemical diversity. Isodon rubescens (Hemsl.) H.Hara is a perennial herb of the genus Isodon in the Labiatae family. Isodon diterpenoids have attracted considerable attention as antibacterial, anti-inflammatory and anti-tumour agents. Oridonin, an ent-kaurane diterpenoid, has been attracting a rising attention in recent years as the main bioactive chemical component of I. rubescens, and it is the material basis for its efficacy. The aim of this study was 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 activities 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