Cytotoxic germacrane-type sesquiterpenes, pimarane-type diterpenes, and a naphthalene derivative from Wollastonia biflora

Phytochemical investigation of the whole plants of Wollastonia biflora led to the isolation and identification of three new germacrane-type sesquiterpenes (1-3), two new pimarane-type diterpenes (4, 5), and a new naphthalene glycoside (6), along with 11 known compounds. Their structures were characterized on the basis of spectroscopic analyses and chemical methods. Compounds 1, 2, and 3 showed significant cytotoxic activity against the growth of hepatocellular carcinoma BEL-7402 cells in vitro.