Effects of Curcumin and Silymarin on the Shigella dysenteriae and Campylobacter jejuni In vitro

J Gastrointest Cancer. 2020 Sep;51(3):824-828. doi: 10.1007/s12029-019-00301-1.

Abstract

Objective: Antimicrobial properties of silymarin and curcumin have been assessed against several infectious agents. The aim of this study was to investigate the anti-apoptotic and antibacterial effects of both compounds on the expression of genes among Shigella dysenteriae ATCC 12022 and Campylobacter jejuni subsp. jejuni strain ATCC 33560 standard strains.

Methods: S. dysenteriae and C. jejuni standard strains were prepared from reference laboratory. Additionally, two clinical multidrug-resistant (MDR) isolates were adopted. Silymarin and curcumin stocks were purchased from Sigma Corporation (USA), and after preparation of dilutions (0.5-512 μg/ml), the minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC) were determined. Furthermore, the effect of 100 μg/ml of each compound was also evaluated on the expression of two gyrB and 16S rRNA housekeeping genes by quantitative real-time PCR (qRT-PCR).

Results: Silymarin MIC and MBC were 512 μg/ml and > 512 μg/ml against S. dysenteriae and > 512μg/ml against C. jejuni standard strains, respectively. Moreover, curcumin MIC and MBC concentrations were 256 μg/ml and 512 μg/ml, respectively for ATCC strains. Silymarin down-expressed the expression of gyrB gene in S. dysenteriae and gyrB and 16srRNA gene in C. jejuni significantly (p < 0.05) compared with unexposed strains. In addition, curcumin could down-express the both gyrB and 16S rRNA genes in both strains significantly (p < 0.05). For two MDR clinical isolates, both MIC and MBC of compounds were > 512 μg/ml. Addition of 100 μg/ml curcumin and silymarin to ampicillin (10 μg/ml) lowered the MIC of MDR S. dysenteriae to 256 μg/ml and 512 μg/ml, respectively. However, no MIC change was observed with regard to C. jejuni.

Conclusion: In this study, curcumin and silymarin could inhibit the growth of S. dysenteriae and C. jejuni and 100 μg/ml sub-MIC levels exhibited the suppression of housekeeping genes. Combating pathogenic bacteria by compounds alternative to antibiotics in the era of antibiotic resistance is a proper strategy, though more studies using combinations of them are needed.

Keywords: Campylobacter jejuni; Curcumin; Shigella dysenteriae; Silymarin; Virulence.

MeSH terms

  • Ampicillin / pharmacology
  • Ampicillin / therapeutic use
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use
  • Campylobacter / drug effects*
  • Campylobacter / genetics
  • Campylobacter Infections / drug therapy
  • Campylobacter Infections / microbiology
  • Curcumin / pharmacology*
  • Curcumin / therapeutic use
  • DNA Gyrase / genetics
  • DNA, Bacterial / isolation & purification
  • Down-Regulation / drug effects
  • Drug Resistance, Multiple, Bacterial / drug effects
  • Drug Resistance, Multiple, Bacterial / genetics
  • Drug Therapy, Combination / methods
  • Dysentery, Bacillary / drug therapy
  • Dysentery, Bacillary / microbiology
  • Gene Expression Regulation, Bacterial / drug effects
  • Genes, Essential
  • Humans
  • Microbial Sensitivity Tests
  • RNA, Ribosomal, 16S / genetics
  • Shigella dysenteriae / drug effects*
  • Shigella dysenteriae / genetics
  • Silymarin / pharmacology*
  • Silymarin / therapeutic use

Substances

  • Anti-Bacterial Agents
  • DNA, Bacterial
  • RNA, Ribosomal, 16S
  • Silymarin
  • Ampicillin
  • DNA Gyrase
  • Curcumin

Supplementary concepts

  • Campylobacter jejuni subsp. jejuni