In this study, we explored anti-inflammatory compounds from the brown alga Dictyopteris polypodioides and isolated 7 meroterpenoids. Their anti-inflammatory activities were evaluated using the lipopolysaccharide (LPS)-stimulated mouse macrophage cell line, RAW264. Yahazunol (1) exhibited similar nitric oxide (NO) production inhibitory activity as zonarol (2), which has previously been shown to be an anti-inflammatory compound. Yahazunol (1), zonarol (2), and isozonarol (3) inhibited not only nitric oxide production but also inducible nitric oxide synthase (iNOS), interleukin-6 (IL6), and C-C motif chemokine ligand 2 (CCL2) mRNA expression in RAW264 cells. The structure-activity relationships of the 11 compounds, including their synthetic analogs, revealed the significance of the hydroquinone moiety in the anti-inflammatory activity of these sesquiterpenoids in RAW264 cells. Diacetylated zonarol (9) exhibited an activity comparable to that of zonarol as a result of intracellular deacetylation. These results provide new insights into the anti-inflammatory activity of hydroquinone-containing natural products.
Keywords: Dictyopteris polypodioides; anti-inflammatory; hydroquinone; yahazunol; zonarol.
© The Author(s) 2024. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.