A new cytotoxic pentacyclic alkaloid, citrinadin C (1), together with four known compounds (2-5), were isolated from deep-sea-derived fungus Penicillium citrinum. The structure of new compound 1 was elucidated by extensive 1D and 2D NMR and Mass spectroscopic data, and its absolute configuration was determined by CD spectrum. All the compounds were evaluated for their cytotoxic and antibacterial activities. Compound 1 showed cytotoxic activities against human liver cancer cell line MHCC97H, with IC50 value of 16.7 μM. Compound 4 displayed significant antibacterial activity against phytopathogen Xanthomonas campestris, with MIC value of 25 μM.© 2022. This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.