Three new (1-3), together with three known (4-6) quinoline alkaloids were isolated from the leaves of cigar tobacco (a variety of Nicotiana tabacum). Their structures were elucidated by spectroscopic methods, including extensive 1H, 13C, and 2D-NMR techniques. Compounds 1-6 were tested for their anti-tobacco mosaic virus (anti-TMV) activity. The results showed that compound 3 exhibited high anti-TMV activity with inhibition rate of 42.2% at the concentration of 20 μM. This rate in higher than that of positive control (with inhibition rate of 32.5% at the concentration of 20 μM). Compounds 1, 2, 4∼6 also showed potential anti-TMV activity with inhibition rates of 28.2, 31.0, 22.8, 26.6, and 29.5% at the concentration of 20 μM, respectively. These rates are slightly lower than that of positive control. © 2021 Japan Institute of Heterocyclic Chemistry. All rights reserved.