Phloroglucinol possesses anti-inflammatory activities by regulating AMPK/Nrf2/HO-1 signaling pathway in LPS-stimulated RAW264.7 murine macrophages

Abstract

Background

Inflammation is closely related to the pathogenesis of chronic illnesses. Secondary metabolites of marine seaweeds are recognized as reliable sources of bioactive compounds due to their health benefits besides their nutritional value. The objective of this study was to determine the potential anti-inflammatory effect of phloroglucinol (Phl) in RAW264.7 murine macrophages after lipopolysaccharides (LPS) stimulation.

Methods

MTT, nitric oxide (NO), and DCFH-DA assays were conducted to determine cell viability, NO production, and reactive oxygen species (ROS) generation respectively. Pro-inflammatory cytokines and prostaglandin E₂ (PGE₂) levels were measured using ELISA assay kits. Protein expression levels were determined by western blot analysis.

Results

Phl treatment showed a promising anti-inflammatory effect by reducing NO production, secretion of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6), PGE₂ production, protein expression levels of inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), and ROS generation in LPS-stimulated RAW264.7 murine macrophages. Phl treatment upregulated heme oxygenase-1 (HO-1) expression by inducing nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and activating AMPK. However, Zinc protoporphyrin (ZnPP), an inhibitor of HO-1, partially reversed these effects, including NO production, pro-inflammatory cytokine secretion, iNOS, COX-2 and HO-1 expression, and ROS generation.

Conclusion

Phl has potential anti-inflammatory activities by regulating AMPK/Nrf2/HO-1 pathway in LPS-stimulated RAW264.7 murine macrophages.

Keywords:

• Phloroglucinol: HO-1
• anti-inflammatory
• RAW264.7 macrophage
• LPS

Author contributions

Methodology, Investigation, Formal analysis and Draft writing, C.K.M., Funding acquisition, W.K. J., Writing and Editing, Funding acquisition, Data curation, and Supervision, J.Y.J. All authors have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All data generated or analyzed during this study are included in this published article.

Additional information

Funding

This study was supported by grants [NRF-2021R1I1A3047702 and 2021R1A6A1A03039211] of the Basic Science Research Program through the National Research Foundation (NRF) funded by the Ministry of Education, Republic of Korea.