Anti-inflammatory Effect of Predimenol, A Bioactive Extract from Phaleria macrocarpa, through the Suppression of NF-κB and COX-2.

Background: Inflammation is the response to the reaction of any type of bodily injury by elevating cellular metabolism and releasing soluble mediators. It is also a contributing factor of pain. Predimenol, which has previously been known as DLBS1442, is a bioactive extract from Phaleria macrocarpa (Scheff.) Boerl (Thymelaceae). It can be an alternative treatment for pain relief, especially for long-term use.

Objective: The objective of this study is to evaluate the anti-inflammatory activities of predimenol through the evaluation of several parameters involved in the inflammatory pathway.

Methods: Cyclooxygenase 2 (COX-2), inducible nitric oxide synthase (iNOS), tumor necrosis factor-  (TNF-), interleukin-1β (IL-1β), interleukin-2 (IL-2), interleukin-6 (IL-6), and nuclear factor B (NF-B) were observed after 24 h exposure of predimenol (0-180 µg/mL) to lipopolysaccharides (LPS)-activated RAW 264.7 cell. The inflammatory markers were measured using nitric oxide (NO) assay and enzyme-linked immunosorbent assay (ELISA) for COX-2 inhibitor assay. The gene expressions of TNF-α, IL-1β, IL-2 and IL-6 were quantified using the polymerase chain reaction (PCR) method. Western blotting was applied to detect phosphorylated IB kinase (IKK) protein to confirm the activation of NF-κB.

Results: Our study showed a similar mechanism with most non-steroidal anti-inflammatory drugs (NSAIDs). Predimenol consistently downregulated the expression of iNOS and inhibited COX-2 activity. Moreover, predimenol significantly inhibited the LPS-induced production of NO, TNF-α, IL-1β, IL-2 and IL-6. Down-regulation of these markers was suggested due to the reduction of NF-κB transcription level and activation by predimenol.

Conclusion: Predimenol exhibits anti-inflammatory activities through NF-kB inactivation-mediated COX-2 suppression, which may suggest that predimenol is a potential analgesic and anti-inflammatory agent.