New meroterpenoids and C-methylated flavonoid isolated from Baeckea frutescens.

Phytochemical investigation of the aerial parts of Baeckea frutescens resulted in the isolation of three new mono- or sesquiterpene-based meroterpenoids, frutescones S-U (1-3), and one pair of new (±)-5,7-dihydroxy-8-isobutyryl-6-methyldihydroflavonol (4). Their structures and absolute configurations were established by HR-ESI-MS, 1D and 2D NMR, and quantum chemical ECD calculation. Compound 1 exhibited inhibitory effect on NO production in LPS-activated RAW 264.7 macrophages with an IC ₅₀ value being 0.81 μmol·L ^-1 .
(Copyright © 2020 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.)