Pyrroloquinolinone methylderivatives, furocoumarin analogues: synthesis and biological activity.
Searching new photochemotherapeutic agents, a series of methylpirroloquinolinones were prepared by a new synthetic pathway, thus univocally obtaining the title compounds. The photobiological activity of some of these compounds was assayed; upon UVA activation, a marked capacity of inhibiting macromolecular synthesis in Ehrlich cells was observed, which appeared to be markedly high testing protein synthesis. Pyrroloquinolinones induced a strong inhibition of the clonal growing capacity of HeLa cells cultivated in vitro. Studying DNA photodamage in HL60 cells high amounts of single strand breaks and DNA-protein cross-links were detected. Pyrroloquinolines inhibited T2 bacteriophage infectivity, but induced no significant amounts of revertants in E. coli WP2 TM9, a strain very sensitive to DNA damage. On the contrary, 8-MOP, tested in the same experimental conditions exhibited an evident photomutagenecity. These data suggest that pyrroloquinolines induced antiproliferative effects by a mechanism in which DNA-photobinding practically does not takes place, and therefore different from that shown by known furocoumarins. Pyrroloquinolinones showed also a moderate antiproliferative activity in the dark.