Three new flavonoids from the leaves of oriental tobacco and their cytotoxicity

Three new flavonoids, 6,7-dimethoxy-4'-hydroxy-8-formylflavon (1), 8-formyl-4',6,7-trimethoxyflavon (2), 4',7-dihydroxy-8-formyl-6-methoxyflavon (3), together with fifteen known flavonoids (4-18) were isolated from the leaves of oriental tobacco (a variety of Nicotiana tabacum L). Their structures were determined by means of HRESIMS, extensive 1D and 2D NMR spectroscopic studies and chemical evidences. The cytotoxicity against five human tumor (NB4, A549, SHSY5Y, PC3, and MCF7) cell lines of compounds 1-3 were also evaluated. The results showed that compounds 1 and 3 showed high cytotoxicity against PC3 and A549 cell lines with IC50 values of 2.6 and 1.6 mu M, respectively. (C) 2012 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.