Abstract

Dental pulp inflammation expresses many pro-inflammatory cytokines; interleukins, cyclooxygenase (COX)-2 and prostaglandin E₂ (PGE₂). Inflammatory reduction and promoting regeneration of dental pulp cells are advantage for dental pulp healing. Zingiber cassumunar Roxb. (Phlai) has anti-inflammatory activity which may be applied to decrease inflammation in dental pulp tissues. The present study had aimed to evaluate inhibitory effect of Phlai constituents on COX-1, COX-2 and PGE₂ expression inhuman dental pulp cells stimulated with lipopolysaccharide (LPS). After cells were inhibited with dexamethasone (cox-inhibitor) or Phlai constituents for 2 h, LPS were added and concentration adjusted to 100 µg/ml. COX-1 and COX-2 gene expressions were obtained by reverse-transcription polymerase chain reaction (RT-PCR) and realtime RT-PCR after incubating for 24 h. COX-1 and COX-2 protein expressions were identified by Western blot and PGE₂ level was detected by enzyme linked immunosorbent assay (ELISA) after incubating for 72 h. These Phlai constituents as cis-3-(3',4'-Dimethoxyphenyl)-4-[(E)-3"',4"'-dimethoxystyryl]cyclohex-1-ene (compound B), cis-3-(2',4',5'-Trimethoxyphenyl)-4-[(E)-2"',4"',5"'-trimethoxystyryl]cyclohex-1-ene (compound C) and (E)-1-(3',4'-Dimethoxyphenyl)but-1,3-diene (DMPBD) could reduce PGE2 level and COX-2 expression.cis-3-(3',4'-Dimethoxyphenyl)-4-[(E)-2"',4"',5"'-trimethoxystyryl]cyclohex-1-ene (compound C¢) reduced PGE₂ levels but had less effect on COX-2. All constituents showed no significant change on COX-1. Our results suggest that some constituents of Phlai can reduce inflammation in human dental pulp cells by reducing COX-2 and PGE₂ production.

Key words: Zingiber cassumunar, Phlai, cyclooxygenase-1, cyclooxygenase-2, lipopolysaccharide, anti-inflammation, dental pulp cells, prostaglandin E_2.