A novel bioactive adjacent bis-tetrahydrofuran (THF) acetogenin, asitribin (1), and two novel bioactive mono-THF acetogenins with double bonds, asiminenins A (2) and B (3), were isolated from the seeds of Asimina triloba (Annonaceae) by directing the fractionation with brine shrimp lethality. In addition, asimicin, bullatacin, trilobacin (4) and trilobin (5), which are known, and parviflorin, which is known but is new in this species, were obtained. 1 has anerythro configuration between the two THF rings, as do trilobacin (4) and trilobin (5), and is a structural isomer of 4 and 5. 1 showed potent cytotoxicities among six human solid tumor cell lines with notable selectivity for the lung cell line (A-549). 2 and 3 also exhibited potent and selective bioactivities across the six cell lines. 3 with the trans configuration of the mono-THF ring was more bioactive and selective than 2 with the cis configuration.