Alkaloid constituents from the stems of Dendrobium nobile and their anti-inflammatory activities
TL;DR
Among them, compound 1 displayed the most potent anti-inflammatory activity, with an IC50 value of 9.05 ± 1.60 μM, comparable to that of the positive control dexamethasone.
Abstract
A phytochemical investigation of the stems of Dendrobium nobile Lindl. led to the isolation of six nitrogen-containing compounds, including one previously undescribed quinoline–aspartic acid hybrid alkaloid, dendronobiline A (1), together with five known alkaloid-related constituents (2–6). The structure of compound 1 was elucidated by comprehensive spectroscopic analyses, including HRESIMS, 1D and 2D NMR experiments, and its absolute configuration was assigned by comparison of experimental and calculated ECD spectra. Structurally, compound 1 features a quinoline-derived unit connected to a dimethyl aspartate moiety through an amide linkage. All isolated compounds were evaluated for their inhibitory effects on LPS-induced nitric oxide production in RAW264.7 macrophages. Among them, compound 1 displayed the most potent anti-inflammatory activity, with an IC50 value of 9.05 ± 1.60 μM, comparable to that of the positive control dexamethasone. These findings enrich the chemical diversity of D. nobile alkaloids and suggest that its stems are a promising source of anti-inflammatory natural products.