Phenanthrenoids and oxoaporphine alkaloids from Monoon fuscum B. Xue & R.M.K. Saunders and their biological activities.

Phytochemical investigation of the twigs of Monoon fuscum (Annonaceae) led to the isolation and characterisation of eight compounds, including a new phenanthrenoid, 2-(2-hydroxy-3,6,7-trimethoxyphenanthren-1-yl)ethyl acetate (1), together with seven known compounds (2-8). The structure of the new compound was elucidated through extensive spectroscopic analysis, including 1D and 2D NMR and HRESIMS. All compounds were evaluated for the nitric oxide (NO) production inhibitory activity in LPS-induced RAW 264.7 cells and cytotoxicity against the colorectal (SW-480) cancer cell line. Oxostephanine (4), oxostephanosine (5), and (-)-oxoisocorypalmine (8) exhibited moderate inhibitory effects on NO production in LPS-induced RAW 264.7 cells with IC50 >2 µM. Perakensol (2) exhibited the strongest cytotoxicity against SW-480 cells with an IC50 value of 392.30 ± 70.59 µM. Notably, new compound 1 demonstrated the highest selectivity (SI = 2.18) towards cancer cells over normal colon epithelial (CCD-841 CoN) cells.