Half‐Wave Potentials of 1‐AZA‐ and 1,8‐Diazaanthraquinones

Abstract

The redox propexties of a series of l-azaanthracene-9,10-diones, l$-diazaanthracene-9,10-diones, 1 $-diazaanthracene-(lH)2,9,1O-triones and 1,8-diazaanthracene-(lH, 8H)2,7,9,lO-terraones have been studied. The results obtained show that the 2-pyridone moiety is a stronger electron acceptor than the pyridine ring, in agreement with reactivity data. 1-Hydroxy-lazaanthracene-2,9,10-triones, synthesized from l-azaanthracene-9,1O-dione-N-oxides, show redox properties close to 1,8-diazaanthracene-2,7,9,lO-tetraones, and therefore the cyclic hydroxamic acid unit behaves also as an strong electron acceptor. Voltammetric half-wave fist potentials correlate with the energies of the LUMO in model compounds. INTRODUCTIONThe redox properties of heterocyclic quinones have attracted considerable interest1 and their study is of relevance in the understanding of the biological roles of these compounds. Many well-known antitumour agents, including mitoxantrone, the anthracyclines, the naphthyridinomycinsaframycin family, and the mitomycins have a quinone

Investigation on the electrochemistry and cytotoxicity of the natural product marcanine A and its synthetic derivatives

“…To explore the electrochemistry of marcanine A 1 and its synthesized derivatives (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) cyclic voltammetry (CV) and differential pulse voltammetry (DVP) experiments were performed using a conventional three-electrode cell in deaerated solutions. All experiments were conducted in the aprotic solvent dimethylformamide (DMF) with tetrabutylammonium hexa-uorophosphate (TBAPF 6 ) as supporting electrolyte on platinum working and counter electrodes.…”

“…Interestingly, compounds 5 and 9, both with an electron donating methoxy substituent, were separated experimentally Fig. 2 Constitution of the synthesized marcanine A derivatives (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) used in this study. by 0.128 V. This result signies that the methoxy substituent at the C-3 position stabilizes the radical anion in 9 better compared to 5 and reduces the electron affinity of the quinone moiety.…”

“…cis-Platin and doxorubicin were used as positive controls. The ability of marcanine A 1 and its derivatives (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) to inhibit the Table 1 Comparison of experimental formal potentials for the first (E 0 1 ) and second reduction (E 0 2 ) with the calculated adiabatic electron affinity (E a ) for tested marcanine A 1 and its derivatives (4-13) growth of both cancer cell lines is represented in Fig. 5.…”

“…6). Compounds (12)(13)(14) with a pyridine scaffold and lower formal potentials E 0 1 showed also the lowest cytotoxic effect. Following the trend, compounds 5-9 with the 2-pyridone scaffold and higher formal potentials E 0 1 compared to the pyridine series were also several times more active in the cellular assay (Fig.…”

“…In order to investigate the role of the quinone moiety as a relevant scaffold in azaanthracenone natural products, manipulation of the redox potential of the quinone motif was performed to explore the structure-toxicity-relationship with the ultimate aim of designing novel molecules with improved anticancer activity. Ten marcanine A derivatives (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) with different substitution patterns were synthesized with variation in size and electrochemical properties of the functional groups attached to the azaanthracenone scaffold (Fig. 2).…”