Inhibition of the human ether-a-go-go-related gene (HERG) K+ channels by Lindera erythrocarpa

Linderanidins A-F: Rare oligomeric flavonoids with an unusual C-3-C-4 linkage from the roots of Lindera erythrocarpa and their inhibitory activities on autophagy

Autophagy is a crucial process for maintaining cellular homeostasis by degrading and recycling unnecessary or damaged cellular components. In the process of exploring autophagy regulators in plants, unique nine oligomeric flavonoids linked by the bonding of C-3 and C-4, consisting of three pairs of biflavonoids, linderanidins A-C [(+)-1/(-)-1, (+)-2/(-)-2, and (+)-3/(-)-3], and three trimeric A-type proanthocyanidins, linderanidins D-F (4-6), were isolated from the roots of Lindera erythrocarpa. The structures and absolute configurations of these compounds were determined using various techniques, such as 1D and 2D NMR, mass spectrometry, X-ray crystallography, and electronic circular dichroism. All isolates were evaluated for their ability to regulate autophagy, and compounds (±)-1-(±)-3, (-)-1-(-)-3, (+)-1-(+)-3 and 4 were found to inhibit autophagy by blocking the fusion process between autophagosome and lysosome in HEK293 cells. This study suggests that unique oligomeric flavonoids possessing a C-3-C-4 linkage derived from the roots of L. erythrocarpa are potent autophagy inhibitors.

Anti-inflammatory effect and mechanism of action of Lindera erythrocarpa essential oil in lipopolysaccharide-stimulated RAW264.7 cells

The aim of this study was to investigate the chemical constituents of Lindera erythrocarpa essential oil (LEO) by gas chromatography-mass spectrometry and evaluate their inhibitory effect on the expression of pro-inflammatory mediators in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Fifteen compounds, accounting for 63.7 % of the composition of LEO, were identified. The main compounds were nerolidol (18.73 %), caryophyllene (14.41 %), α-humulene (7.73 %), germacrene-D (4.82 %), and α-pinene (4.47 %). LEO significantly inhibited the expression of inducible nitric oxide (NO) synthase and cyclooxygenase-2, and subsequent production of NO and prostaglandin E₂. In addition, it reduced the release of pro-inflammatory cytokines in LPS-activated RAW264.7 cells. The molecular mechanism underlying the effect of LEO was associated with inhibition of the phosphorylation of mitogen-activated protein kinase (MAPK). Furthermore, LEO inhibited LPS-induced phosphorylation and degradation of inhibitor of kappa B-α, which is required for the activation of the p50 and p65 nuclear factor (NF)-κB subunits in RAW264.7 cells. Taken together, these data suggest that LEO exerted its anti-inflammatory effect by downregulating LPS-induced production of pro-inflammatory mediators through the inhibition of NF-κB and MAPK signaling in RAW264.7 cells.