The alkaloids aristoteline (<b>1</b>), aristoquinoline (<b>2</b>), and aristone (<b>3</b>) were purified from the leaves of the Maqui tree <i>Aristotelia chilensis</i> and chemically characterized by NMR spectroscopy. The pharmacological activity of these natural compounds was evaluated on human (h) α3β4, α4β2, and α7 nicotinic acetylcholine receptors (AChRs) by Ca<sup>2+</sup> influx measurements. The results suggest that these alkaloids do not have agonistic, but inhibitory, activity on each receptor subtype. The obtained IC<sub>50</sub> values indicate the following receptor selectivity: hα3β4 > hα4β2 ≫ hα7. In the particular case of hα3β4 AChRs, <b>1</b> (0.40 ± 0.20 μM) and <b>2</b> (0.96 ± 0.38 μM) show higher potencies compared with <b>3</b> (167 ± 3 μM). Molecular docking and structure-activity relationship results indicate that ligand lipophilicity is important for the interaction with the luminal site located close to the cytoplasmic side of the hα3β4 ion channel between positions -2' and -4'. Compound <b>1</b> could be used as a molecular scaffold for the development of more potent noncompetitive inhibitors with higher selectivity for the hα3β4 AChR that could serve for novel addiction and depression therapies.