A first aspect of the- invention relates to a compound of formula (I), or a pharmaceutically acceptable salt or ester thereof, (Formula (I)) wherein : R1 is (CH2)mNR11R12; R2 is selected from H, halo, OR13, ΝΗR13, alkyl, alkenyl and alkynyl; R3 is selected from alkyl, alkenyl, alkynyl, aryl, halo, aryloxy, NHCO2R4, NHCONR5R6, NHCOR7, NH-alkyl, NH-alkenyl, NH(CH2); n-aryl, (CH2)p-heteroaryl, (CH2)qCO2R8, (CH2)rCOR9 and NHSO2R10, wherein each alkyl, alkenyl, aryl or heteroaryl moiety in the aforementioned list is optionally further substituted by one or more groups selected from alkyl, halo OH, NH2, alkoxy, aryloxy, alkylamino, arylamino, carboxyl and carboxamide; R4 to R10 and R13 are each independently selected from alkyl, alkenyl and aryl; R11 and R12 are each independently selected from alkyl and alkenyl; or R11 and R : 12 are linked together with the nitrogen to which they are attached to form a heterocycloalkyl or heterocycloalkenyl group; n, m, p, q and r are each independently selected from 0, 1, 2, .3. 4, 5 and 6. Further aspects relate to pharmaceutical compositions, therapeutic uses and process for preparing according to the invention.