Chemical Constituents from Hymenocallis littoralis

Background: Hymenocallis littoralis is the unique genus in China and famous for its high content of alkaloids with anti-tumor activity. However, about twenty alkaloids were isolated and identified in this plant. Methods: The dichloromethane extract of H. littoralis (alkalization with 1% NaOH for 24h) was further subjected to normal-phase silica, ODS silica gel column chromatography, and semi-preparative HPLC chromatography, respectively. Chemical structures of these compounds were identified and elucidated by spectroscopic methods including 1D-NMR, 2D-NMR, and HR-MS. The cytotoxic activities of the new component were determined with the cell lines of HepG-2, LoVo, Hela and A549 using the MTT method after incubation for 48 h. Results: One new alkaloid, named Hymenolitatine (1), with two known compounds was obtained from the bulb of H. littoralis. The chemical structure of the new natural product was elucidated by spectroscopic analysis and comparison with literature data. The two known compounds were identified as trispheridine (2), tazettine (3), on the basis of comparison of their spectral data with the reported data, respectively. The IC50 values of the compound 1 on HepG-2, LoVo, Hela and A549 cell lines were 75.19, 69.81, 96.37 and 102.53 μM, respectively. Conclusion: This is the first report on the isolation and identification of Hymenolitatine (1), and this novel compound exhibited moderate cytotoxic activities against HepG-2, LoVo, Hela and A549 cell lines in vitro. Compound 2 was isolated from the title plant for the first time.