Three meroterpenoids, including one new compound, ranhuadujuanine E (1), one new natural product, methyl (E)-3-(3,7-dimethylocta-2,6-dien-1-yl)-2,4-dihydroxy-6-methylbenzoate (2), and one known compound, ranhuadujuanine D (3), along with two known sesquiterpenoids (4-5) were isolated from Rhododendron racemosum. Their structures were elucidated on the basis of extensive spectroscopic analysis, and the absolute configuration of C-6' in compound 1 was assigned by using Snatzke's method. Compounds 1-3 had inhibitory effects on LPS-induced NO release in RAW264.7 cells.
Keywords: Ericaceae; Rhododendron racemosum; anti-inflammatory activity; meroterpenoids; ranhuadujuanine E.