An in vitro anti-inflammatory effect of Thai propolis in human dental pulp cells

J Appl Oral Sci. 2023 Jun 5:31:e20230006. doi: 10.1590/1678-7757-2023-0006. eCollection 2023.


Objective: To explore the potential for development of Thai propolis extract as a pulp capping agent to suppress pulpal inflammation from dental pulp infections. This study aimed to examine the anti-inflammatory effect of the propolis extract on the arachidonic acid pathway, activated by interleukin (IL)-1β, in cultured human dental pulp cells.

Methodology: Dental pulp cells, isolated from three freshly extracted third molars, were first characterized for their mesenchymal origin and treated with 10 ng/ml of IL-1β in the presence or absence of non-toxic concentrations of the extract from 0.08 to 1.25 mg/ml, as determined by the PrestoBlue cytotoxic assay. Total RNA was harvested and analyzed for mRNA expressions of 5-lipoxygenase (5-LOX) and cyclooxygenase-2 (COX-2). Western blot hybridization was performed to investigate COX-2 protein expression. Culture supernatants were assayed for released prostaglandin E2 levels. Immunofluorescence was conducted to determine involvement of nuclear factor-kappaB (NF-kB) in the inhibitory effect of the extract.

Results: Stimulation of the pulp cells with IL-1β resulted in the activation of arachidonic acid metabolism via COX-2, but not 5-LOX. Incubation with various non-toxic concentrations of the propolis extract significantly inhibited upregulated COX-2 mRNA and protein expressions upon treatment with IL-1β (p<0.05), resulting in a significant decrease in elevated PGE2 levels (p<0.05). Nuclear translocation of the p50 and the p65 subunits of NF-kB upon treatment with IL-1β was also blocked by incubation with the extract.

Conclusions: Upregulated COX-2 expression and enhanced PGE2 synthesis upon treatment with IL-1β in human dental pulp cells were suppressed by incubation with non-toxic doses of Thai propolis extract via involvement of the NF-kB activation. This extract could be therapeutically used as a pulp capping material due to its anti-inflammatory properties.

MeSH terms

  • Anti-Inflammatory Agents* / pharmacology
  • Arachidonic Acid / pharmacology
  • Cells, Cultured
  • Cyclooxygenase 2 / metabolism
  • Dental Pulp* / cytology
  • Dental Pulp* / drug effects
  • Dinoprostone / metabolism
  • Humans
  • NF-kappa B
  • Plant Extracts
  • Propolis* / pharmacology
  • RNA, Messenger / metabolism


  • Anti-Inflammatory Agents
  • Arachidonic Acid
  • Cyclooxygenase 2
  • Dinoprostone
  • NF-kappa B
  • Plant Extracts
  • Propolis
  • RNA, Messenger

Grants and funding

Funding: This study was supported by the Fundamental Fund of Khon Kaen University, has received funding support from the National Science, Research and Innovation Fund (NSRF) to P.C.; the Chiang Mai University Presidential Post-Doctoral Fellowship 2019 to A.M and S.K.; and the Fundamental Fund (#R000029994), Thailand Science Research and Innovation to S.K.