Cytotoxic turrianes from Kermadecia elliptica: Hemisynthesis and biological activities of kermadecin A derivatives

Abstract

Kermadecin A is a cytotoxic natural macrocycle, containing a bisresorcinol and a pyran ring. A series of derivatives has been synthesized from the natural product in order to investigate the role of the different substructures in the biological activity. In this series, free phenolic groups play an essential role in the biological activity as demonstrated by the poor activity exhibited by alkylated derivatives. Interestingly, biological activity can be restored by oxidation of the double bond 27,28 of the pyran ring. Nevertheless, if this double bond of kermadecin A is only reduced, then the biological activity is not affected.