Isolation and characterisation of the sesquiterpene lactones from Lactuca sativa L var. anagustata

Lactuca sativa L var. anagustata is widely used as both a delicious vegetable and a traditional medicine in China. Chemical investigation of the methanolic extract of L. sativa L var. anagustata has now led to the isolation of three new sesquiterpenes, together with eight known ones. All the compounds were isolated by chromatography on a silica gel column and preparative thin-layer chromatography (PTLC). Their structures were elucidated by means of spectroscopic methods, including 2D-NMR experiments. Cytotoxicity of the new compounds was assayed against selected cancer cell lines, including the human epithelial carcinoma (HeLa) and human colon carcinoma (HCT-116) cell lines. Radical-scavenging activities of the seven compounds were determined by DPPH radical-scavenging assay.