Chemical constituents of Lobelia chinensis.

Three new 2, 6-disubstituted piperidine alkaloids (1-3), one new polyacetylene (8), together with eight known compounds (4-7, 9-12) were isolated from the whole plants of Lobelia chinensis. Their structures were elucidated on the basis of spectroscopic data interpretation. The absolute configuration of 1 was established by a convenient Mosher ester procedure in which the sample was treated with MTPA chlorides in deuterated pyridine directly in NMR tube. Cytotoxicities of compounds 1-12 were tested against two human lung cancer cell lines, NCI-H292 and MSTO-211H. Compounds 8 and 9 exhibited moderate cytotoxic activity against the two cancer cell lines with the IC50 values in the range of 9.31-12.36 μM.