Derivatives of ecteinascidin 736 of general formula (I) wherein the groups R1, R2, R3, R4 and R5 are each independently selected from the group consisting of H, OH, OR′, SH, SR′, SOR′, SO2R′, C(═O)R′, C(═O)OR′, NO2, NH2, NHR′, N(R′)2, NHC(O)R′, CN, halogen, ═O, substituted or unsubstituted C1-C25 alkyl, substituted or unsubstituted C2-C18 alkenyl, substituted or unsubstituted C2-C18 alkynyl, substituted or unsubstituted aryl, substituted or unsubstituted heterocyclic; wherein X is independently selected of OR′, CN, (═O), or H; wherein each of the R′ groups is independently selected from the group consisting of H, OH, NO2, NH2, SH, CN, halogen, ═O, C(═O)H, C(═O)CH3, CO2H, substituted or unsubstituted C1-C25 alkyl, substituted or unsubstituted C2-C18 alkenyl, substituted or unsubstituted C2-C18 alkynyl, substituted or unsubstituted aryl; wherein m is 0, 1 or 2; and wherein n is 0, 1, 2, 3, or 4, and their use as antitumoral agent.