Antitumor agents 171. Cytotoxicities of lobatosides B, C, D, and E, cyclic bisdesmosides isolated from Actinostemma lobatum maxim

Cytotoxicities for lobatosides B—E and actinostemmosides B—F, isolated from Actinostemma lobatum, were evaluated against a panel of ca 60 human cancer cell lines. Lobatosides B—E (1–4) were cytotoxic (GI50 ≤ 1 × 10−4 M) against all tumor cell lines; 4 showed potent cytotoxicity especially against A-549, SK-MEL-5, and SW-620 cell lines with GI50 values of 0.14, 0.14, and 0.36 μM, respectively.