Three new phomoxanthone compounds, phomolactonexanthones A (1), B (2) and deacetylphomoxanthone C (3), along with five known phomoxanthones, including dicerandrol A (4), dicerandrol B (5), dicerandrol (6), deacetylphomoxanthone B (7) and penexanthone A (8), were isolated in the metabolites of the fungus Phomopsis sp. HNY29-2B, which was isolated from the mangrove plants. The structures of compounds 1–3 were established on the basis of spectroscopic analysis. All compounds were evaluated against four human cancer cell lines including human breast MDA-MB-435, human colon HCT-116, human lung Calu-3 and human liver Huh7 by MTT assay. The compounds 4, 5, 7 and 8 showed cyctotoxic activities against tested cancer cell lines (IC50 < 10 μM).
