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

One new isoprenylated resorcinoid (1) and one new chromene meroterpenoids (2) along with eight known compounds (3-10) were isolated from the leaves of Rhododendron dauricum 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 3, 8-9 were isolated from the Ericaceae family for the first time. The anti-inflammatory effects of compounds 1-10 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 5 exhibited significant NO secretion effect with an IC₅₀ value of 7.59 ± 0.45 µM. Furthermore, molecular docking analyses indicated that compound 5 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.