Dactyllactone A (1), which was isolated from Dactylicapnos scandens, is an isoquinoline alkaloid with a rearranged and reconstructed D ring, making it the first of a new subtype of aporphines. Compound 1 might be derived from a common aporphine skeleton, which may have undergone biogenetic rearrangement and cleavage of the aromatic ring. Its structure was determined by extensive spectroscopic analysis and single-crystal X-ray diffraction. Compound 1 exhibited anti-inflammatory activity in vitro significantly by inhibiting the expression of IL-1β and PGE2 in a dose-dependent manner.