A series of compounds 1-11 with different side chains of naphthalimide as fluorescent copper sensors were designed and synthesized. Compounds 1, 9, 10 and 11 presented a high selectivity to Cu2+ in a neutral aqueous environment. Here 1, 9 and 10 showed selectivity and affinity to Cu2+ with an association constant of about ～106. It gave somewhat response to Ag+, Co2+, Ni2+ and Fe2+ while 1 detected copper. 9 and 10 displayed better selectivity by changing their hydrophobic side chains to the hydrophilic ones on imide moieties. 11, with one flexible side chain, showed high selectivity and an association constant (Ka = 2.2 × 108), which were much higher than those of 1, 9 and 10. These results indicated that the selectivity and affinity could be improved by changing side chains of naphthalimide. That might provide a novel strategy or method for the development of fluorescent sensors.
In this review, we retrospect our progress in biological active naphthalimide and analogues as antitumor agents in the past 20 years. On one hand, various derivations in naphthalimide pharmacophores were developed to enhance their DNA binding affinity and antitumor property thereby. Heterocyclic fused naphthalimides, bis-naphthalimides, non-fused substituted naphthalimides and the carboxamide derivatives were synthesized. For example, thio-heterocyclic fused-naphthalimides were designed and evaluated in comparison with their oxo-heterocyclic fused analogues. Extended or created heterocyclebased skeleton were also developed as antitumor agents. On the other hand, we broaden the design strategy of naphthalimide antitumor agents besides DNA intercalation and topo II poison. We have introduced more drug design methods, such as prodrugs, multitarget drugs, computer-aided drug design,photodynamic therapy. For example, we have got naphthalimide derivatives which inhibited topo II and induced LMP by introducing long alkyl chain and polyamines. Several representative compounds were clarified of their antitumor mechanism of action. In all, our research improves the structure diversity of naphthalimide antitumor agents and distinct variances of antitumor targets and mechanism of action.
