One new isoprenylated resorcinoid and one new chromene meroterpenoid with potential anti-inflammatory effects from the leaves of <i>Rhododendron dauricum</i> L

One new isoprenylated resorcinoid (<b>1</b>) and one new chromene meroterpenoids (<b>2</b>) along with eight known compounds (<b>3</b>-<b>10</b>) were isolated from the leaves of <i>Rhododendron dauricum</i> L. The chemical structures were elucidated through extensive spectroscopic experiments, including 1D and 2D NMR as well as HR-ESI-MS, in combination with NMR chemical shift calculation coupled with ECD calculations, and comparison with literature reports. Notably, compounds <b>3</b>, <b>8</b>-<b>9</b> were isolated from the Ericaceae family for the first time. The anti-inflammatory effects of compounds <b>1</b>-<b>10</b> were evaluated in terms of inhibition of production of NO, TNF-a, and IL-6 in LPS-induced RAW 264.7 cells. Among these, compound <b>5</b> exhibited significant NO secretion effect with an IC₅₀ value of 7.59 ± 0.45 µM. Furthermore, molecular docking analyses indicated that compound <b>5</b> had binding energies of -6.5 and -6.6 kcal/mol with iNOS and COX-2, respectively. These more favourable (negative) binding energies suggest a stronger binding potential.