The present invention concerns a compound of formula (I) wherein: W represents O or NH, Q represents an unbranched or branched, saturated or unsaturated or aromatic, cyclic or acyclic or heterocyclic hydrocarbon radical containing 1 to 30 carbon atoms including or not heteroatom(s), R1 is H, OH, or R1, R2 form together —O—, R3═R4═OMe or R3 and R4 form together —OCH2O—, R is H, C1-C30alkyl or O-protecting group and R6 represents an unbranched or branched, saturated or unsaturated or aromatic, cyclic or acyclic or heterocyclic hydrocarboned radical containing 1 to 30 carbon atoms including or not heteroatom(s), or R and R6 form together —CMe2-, n is 0 to 8, R5 is H, OH, OMe, O—(C1-C30)-alkyl, O-aryl-(C1-C30)-alkyl, O—(C2-C30)-alkenyl, O—(C3-C30)-cycloalkyl or O-aryl, the dotted line is null or forms a double bond depending on the meaning of R1. It also concerns their methods of preparation and their use in treatment of cancers, leukemias, parasites and as reversal agents of harringtonines.