Reivindicaciones
1. A compound having the formula (I): <img class="EMIRef" id="452401486-ib0012" /> and the dihydro derivative of formula (12): <img class="EMIRef" id="452401486-ib0013" /> wherein R<3> , R<4> , R<7> and R<8> are independently selected from the group consisting of hydrogen, C<1-6> alkyl, halogen, amine, mono(C<1-6> )alkylamine, di(C<1-6> )alkylamine, or phenyl (which may be substituted with 1 to 4 substituents selected from C<1-6> alkyl, halogen, amine, mono (C<1-6> )alkylamine, di(C<1-6> )alkylamine, nitro, hydroxy, C<1-6> alkoxy, or trifluoromethyl); with the exception of the compounds in which: R<3> , R<4> , R<7> and R<8> are all hydrogen; R<3> and R<7> are hydrogen, R<4> is chlorine, and R<8> is a 2-nitrophenyl group; R<3> and R<7> are hydrogen, R<4> is amino, and R<8> is a 2-nitrophenyl group; R<3> , R<7> and R<8> are hydrogen and R<4> is chlorine; and R<4> , R<7> and R<8> are hydrogen and R<3> is methyl. 2. A compound according to claim 1, which is selected from a compound of formula (4): <img class="EMIRef" id="452401486-ib0014" /> formula (8), <img class="EMIRef" id="452401486-ib0015" /> formula (11), <img class="EMIRef" id="452401486-ib0016" /> formula (13), and <img class="EMIRef" id="452401486-ib0017" /> formula (14), <img class="EMIRef" id="452401486-ib0018" /> wherein R<3> , R<4> , R<7> and R<8> are as defined in claim 1. 3. A compound according to claim 1 or 2, wherein the substituent groups R<3> , R<4> , R<7> and R<8> are chosen from hydrogen, methyl, ethyl, chlorine, dimethylamine, and nitrophenyl. 4. A compound according to claim 1 which is selected from: 3,7-diethyl-1,5-diazaanthraquinone; 3,7-dimethyl-1,5-diazaanthraquinone; 4,8-dimethyl-1,5-diazaanthraquinone; 4,8-dimethyl-3,7-dimethyl-1,5-diazaanthraquinone; 8-chloro-3-methyl-1,5-diazaanthraquinone; 8-chloro-1-dimethylamino-4-methyl-1,4-dihydro-1,5-diazaanthraquinone; 4-chloro-8-methyl-1,5-diazaanthraquinone; and 4-dimethylamino-8-methyl-1,5-diazaanthraquinone. 5. A pharmaceutical composition which includes as active ingredient a compound of any one of claims 1 to 4, together with a pharmaceutical carrier. 6. A compound according to any one of claims 1 to 4 for use as a medicament. 7. The use of a compound according to any of claims 1 to 4 or a pharmaceutical composition according to claim 5 in the manufacture of a medicament for the treatment of tumours.