Four new cyclohexylideneacetonitrile derivatives 1–4, named menisdaurins B–E, as well as three known cyclohexylideneacetonitrile derivatives—menisdaurin (5), coclauril (6), and menisdaurilide (7)—were isolated from the hypocotyl of a mangrove (Bruguiera gymnorrhiza). The structures of the isolates were elucidated on the basis of extensive spectroscopic analysis. Compounds 1–7 showed anti-Hepatitis B virus (HBV) activities, with EC₅₀ values ranging from 5.1 ± 0.2 μg/mL to 87.7 ± 5.8 μg/mL.