Punicalagin isolated from Punica granatum husk can decrease the inflammatory response in RAW 264.7 macrophages

INTRODUCTION: Punicalagin, a natural occuring phytochemical extracted from pomegranate (Punica granatum) husk and it shows antioxidant and anti-tumoral activities. Previous studies have shown that Punica granatum can scavenge reactive oxygen intermediates (ROIs) and suppress the biosynthesis of prostaglandins (PGs). However, the anti-inflammatory property of punicalagin has not yet been elucidated. For this aim, we purposed to display the anti-inflammatory effects of punicalagin via measuring prostaglandin E2 (PGE2) and nitric oxide (NO) production and cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) gene expression in LPS induced RAW 264.7 macrophages.
METHODS: LPS-stimulated RAW 264.7 macrophages were treated with punicalagin at concentrations of 0-10 µM. NO levels in all groups were measured by the Griess method and PGE2 levels by ELISA kit. COX-2 and iNOS gene expression levels were measured using Real Time PCR.
RESULTS: According to our experiments, punicalagin decreased the production of PGE2 and NO by RAW 264.7 macrophages in a dose-dependent manner without affecting the viability of cells. Punicalagin attenuated the mRNA expression of iNOS and COX-2 of murine macrophages in a concentration dependent manner. Thus, the inhibition of NO and PGE2 production is at least partly because of the suppression of the transcription of the iNOS and COX-2 gene, respectively.
DISCUSSION AND CONCLUSION: In conclusion, punicalagin is a potent natural compound in inhibiting the inflammatory mediators. Its action can be delivered in vivo through an appropriate feeding scheme. Because the lower toxicity of punicalagin, it might be a suitable compound that can be used for clinical applications.