NO inhibitory constituents from Glycosmis craibii var. glabra

Six new compounds, including three quinolones (1a, 1b, and 2) and three flavanones (3–5), together with seven known analogues (6–13) were isolated from 95% EtOH extract of the stems and leaves of Glycosmis craibii var. glabra. The structures of the new compounds were elucidated based on HRESIMS, UV, and 1D and 2D NMR data analysis. The absolute configurations were determined by Mosher ester and ECD spectral analysis. Compounds 2, 6, 9, and 10 exhibited inhibition of nitric oxide production stimulated by lipopolysaccharide in BV-2 microglial cells with IC₅₀ values in the range of 13.5−20.1 μM, comparable to the positive control of dexamethasone.