Sesquiterpenes from the leaves of Nicotiana tabacum and their anti-tobacco mosaic virus activity

In searching for more bioactive compounds, phytochemical investigations on the acetone extract of the leaves of Nicotiana tabacum resulted in the isolation of two new sesquiterpenes, nicosesquiterpene A and B (1 and 2), along with four known sesquiterpene derivatives (3-6). Structural elucidation of 1 and 2 was performed by spectral methods, such as HRMS, IR, UV, 1D and 2D NMR spectroscopy. Compounds 1 and 2 are the first naturally occurring pterosin-type sesquiterpene bearing an isopropyl moiety. Compounds 1-6 were also evaluated for their anti-tobacco mosaic virus (anti-TMV) activity. The results showed that compounds 1 and 2 exhibited high anti-TMV activity with inhibition rates of 36.7% and 45.6%, respectively, which is higher than that of positive control. The other compounds also showed potential activity with inhibition rates in the range of 22.7%-29.2%. (C) 2016 Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.