Synthesis and evaluation of novel aza-caged Garcinia xanthones

Inspired by the therapeutic potential of the simplified caged xanthones, we have developed a chemical strategy for synthesizing novel aza-caged Garcinia analogues through a regioselective Claisen/Diels-Alder cascade reaction. The origin of regioselectivity has been explained using the DFT method. We have further evaluated the cell proliferation and IKKβ inhibitory activities of these compounds and studied their binding mode with IKKβ by molecular docking. The results suggested that the aza-caged scaffold provides a suitable modification site and the introduction of a hydrophobic moiety leads to improvement in the cytotoxicity and IKKβ inhibitory activity. The aza-caged compound 6c exhibited an IC(50) value of 2.68, 2.10, 8.02 μM against the HepG2, A549 cells and IKKβ, respectively. Mechanism studies with 6c showed that the aza-caged compounds induce apoptosis and cell cycle S phase arrest in A549 cells.