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.