Bioactivity-based analysis and chemical characterization of cytotoxic compounds from a poisonous mushroom, Amanita spissacea, in human lung cancer cells in vitro

As part of our systematic study on Korean toxic mushrooms, bioactivity-guided fractionation of the MeOH extract of Amanita spissacea (Amanitaceae) fruiting bodies and chemical investigation of its cytotoxic fractions led to the isolation of (9E)-8-oxo-9-octadecenoic acid (1), (10E)-9-oxo-10-octadecenoic acid (2), (9E)-8-oxo-9-octadecenoate methyl ester (3), (9Z)-9-octadecenoate-(2'S)-2',3'-dihydroxypropyl ester (4), (9Z)-9-octadecenoic acid (5), and palmitic acid (6). The structures of the isolates were elucidated by NMR spectroscopic analysis and LC/MS analysis. Among the isolated compounds, compounds 1 and 2 exhibited the most potent cytotoxic activity in all human lung cancer cell lines examined, with IC₅₀ values ranging from 255.7 to 321.0 μM and 250.2 to 322.5 μM, respectively. The cytotoxicity of these compounds was also found to be mediated by apoptosis associated with caspase-3 activation. These findings provide experimental evidence suggesting the potential of A. spissacea as a promising natural source for the discovery of novel anticancer drug candidates.