RESUMEN
A series of new Luotonin A derivatives with substituents at rings A and E was synthesized, together with some E-ring-unsubstituted derivatives. Subsequently, the compound library was examined in silico for their binding into a previously proposed site in the DNA/topoisomerase I binary complex. Whereas no convincing correlation between docking scores and biological data from in vitro assays could be found, one novel 4,9-diamino Luotonin A derivative had strong antiproliferative activity based on massive G2/M phase arrest. As this biological activity clearly differs from the reference compound Camptothecin, this strongly indicates that at least some Luotonin A derivatives may be potent antiproliferative agents, however with a different mode of action.
Asunto(s)
Antineoplásicos/farmacología , Simulación del Acoplamiento Molecular , Pirroles/farmacología , Quinonas/farmacología , Antineoplásicos/síntesis química , Antineoplásicos/química , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Estructura Molecular , Pirroles/síntesis química , Pirroles/química , Quinonas/síntesis química , Quinonas/química , Estereoisomerismo , Relación Estructura-Actividad , Células Tumorales CultivadasRESUMEN
Following two orthogonal synthetic routes, a series of all four possible A-ring amino derivatives of the natural product Luotonin A (a known Topoisomerase I inhibitor) was synthesized. In both strategies, intramolecular cycloaddition reactions are the key step. The target compounds were obtained in good yields by mild catalytic transfer hydrogenation of the corresponding nitro precursors. In-vitro evaluation of the antiproliferative activity towards human tumor cell lines revealed the 4-amino compound (5b) to be the most effective agent, showing an interesting profile of cytotoxic activity. Among other effects, a significant G2/M cell cycle arrest was observed for this compound, suggesting that either Topoisomerase I is not the only biological target, or that some atypical mechanism is responsible for inhibition of this enzyme.
Asunto(s)
Alcaloides/síntesis química , Alcaloides/farmacología , Pirroles/síntesis química , Pirroles/farmacología , Quinonas/síntesis química , Quinonas/farmacología , Alcaloides/química , Antineoplásicos/síntesis química , Antineoplásicos/química , Antineoplásicos/farmacología , Puntos de Control del Ciclo Celular/efectos de los fármacos , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Técnicas de Química Sintética , Humanos , Espectroscopía de Resonancia Magnética , Estructura Molecular , Pirroles/química , Quinonas/química , Espectrometría de Masa por Ionización de Electrospray , Relación Estructura-Actividad , Inhibidores de Topoisomerasa I/síntesis química , Inhibidores de Topoisomerasa I/química , Inhibidores de Topoisomerasa I/farmacologíaRESUMEN
An oxidative ring opening reaction of the central ring C in the alkaloid Luotonin A and two of its derivatives was found to occur upon heating with an excess amine and potassium carbonate in dimethylsulfoxide (DMSO) solution in the presence of air oxygen. The structure of the novel amide-type products was elucidated and a possible mechanism for this reaction is proposed. Four of the new compounds show moderate in vitro anticancer activity towards human colon adenocarcinoma cells.