Isolation of a new iso-quinoline alkaloid and cytotoxicity studies of pure compounds and crude extracts of engl.

A new 2-quinolone alkaloid, iso-oligophyline (), and two very unusual C terpenoids, proposed names ravespanol () and ravespanone (), along with two known compounds, β-sitosterol (), and methyl linoleate (), were isolated from the leaf extract of . Methyl linoleate constitutes the first report of isolation from this species. We have already reported the isolation of atanine (), oligophyline (), ravenoline (8), and arborinine ) from the plant. Based on nuclear magnetic resonance (NMR) spectroscopy and mass spectrometric analysis, the structure of the isolated chemicals was determined. The crude fractions and four compounds (,, and ) were evaluated for a cytotoxicity study on a panel of six human stomach cancer cell lines (SCL, SCL-6, SCL-37'6, SCL-9, K-3, N21) by MTT assay. Among the plant extracts and isolated compounds, petroleum ether fraction and compound exhibited the highest cytotoxic activity against SCL and SCL-6 cells, where the IC values were 17.9 and 16.56 μM, respectively.