Antitumor agents, 119 . Kansuiphorins A and B, two novel antileukemic diterpene esters from Euphorbia kansui

: The extract of the roots of Euphorbia kansui, which has been widely used in Chinese folk medicine for the treatment of cancer, demonstrated antileukemic activity against the P-388 lymphocytic leukemia in mice. Bioassay-directed fractionation of the active extract led to the isolation and characterization of two novel antileukemic diterpene esters, kansuiphorin A [1] [13-hydroxyingenol-3-(2,3-dimethylbutanoate)-13-dodecanoate- 20- hexadecanoate] and kansuiphorin B [2] [6,7-epoxy-13-hydroxyingenol-3-(2,3-dimethylbutanoate)-13-do decanoate-20- hexadecanoate], whose structures were established from spectral evidence and chemical transformation. Kansuiphorins A and B demonstrated potent antileukemic activity with T/C greater than or equal to 176 and 177% at 0.1 and 0.5 mg/kg, respectively. The selectivity of kansuiphorin A, which inhibits the growth of particular cell types within the disease-oriented human cancer cell line panels, is discussed.