Anti-inflammatory sesquiterpenoids from the heartwood of Juniperus formosana Hayata

Abstract

Juniperus formosana Hayata (J. formosana) is a commom needlebush cultivar growing in China. Six new compounds (1–6), including four cadinene sesquiterpenoids (1–4), one abietane diterpenoid (5), and one β-naphthol derivative (6), along with 18 known compounds (7–24) were isolated and identified through phytochemical investigation on the heartwood of J. formosana. The structures of these compounds were fully elucidated by their 1D and 2D NMR, HR-ESI-MS, UV, and IR spectral data analyses. The absolute configurations of compounds 1, 3, and 5 were confirmed by experimental and calculated electronic circular dichroism (ECD) data. Moreover, X-ray crystallographic analysis was carried out to characterize the structure of compound 4. The inhibitory effects on the nitric oxide (NO) production of all the isolated compounds were initially examined in RAW264.7 macrophages induced by lipopolysaccharide (LPS). The results showed that compounds 3 and 12 possessed significant inhibitory potency on NO generation with IC50 values of 3.41 μM and 6.15 μM among the new and known compounds, respectively. The expressions of IL-1β, IL-6, and TNF-α were measured in LPS-stimulated RAW264.7 cells to evaluate the anti-inflammatory effects of compounds 1–24. Compounds 1–6 and 9–12 exhibited potent anti-inflammatory effects. Additionally, the expressions of p38, Erk, and IκBα proteins were further determined to explore the anti-inflammatory mechanism of the most potent compounds 3 and 12. Overall, our findings indicate the potential of J. formosana for developing medicine candidates as the treatments of inflammation.