This study was aimed to evaluate the efficacy and safety of Asimina triloba extracts and its alkaloidal constituents in terms of their cytotoxicity and neurotoxicity towards different cell lines. Six alkaloids (anolobine-9-O-β-d-glucopyranoside, anolobine, norushinsunine, liriodenine, squamolone and coclaurine) were evaluated for their cytotoxic potential in four human solid tumor cell lines (SK-MEL, KB, BT-549, and SK-OV-3). The potential for neurotoxicity was determined using rat cortical neurons. Three extracts, namely a crude methanolic extract, an alkaloid-rich extract, and an acetogenin-rich extract, were also included in the study. The acetogenin-rich extract was the most potent, among all tested extracts, towards SK-MEL, KB, and BT-549 cells with IC50 values in the range of 0.09–0.11 µg/mL. Also, the same extract was found to be significantly toxic to the neurons at 10 µg/mL. The alkaloid-rich extract also showed cytotoxicity, albeit with lower potency, towards SK-MEL, KB, and BT-549 cell lines with IC50 values in the range of 1.7–2.6 µg/mL. Out of the six isolated alkaloids, three alkaloids (anolobine-9-O-β-D-glucopyranoside, norushinsunine, and liriodenine) demonstrated cytotoxic activity. Although the alkaloidal extract did not show any toxicity to neurons up to 10 µg/mL, the pure alkaloids were toxic to the neurons in a concentration-dependent manner. In conclusion, this study underlines the contribution of the alkaloidal constituents in the neurotoxicity and cytotoxicity of A. triloba.