Garcinone D is a naturally occuring xanthone isolated from mangosteen, acting as an inhibitor of NF-κB p65 and p50 activation, exhibiting cytotoxicity against several cancer cell lines. Garcinone D increases the protein levels of phosphorylated signal transducer and activator of transcription 3 (p-STAT3), Cyclin D1 and nuclear factor erythroid 2-related factor (Nrf2), heme oxygenase-1 (HO-1) in concentration- and time- dependent manners.