TP53 and cancer: Considering the disclosed mechanism elucidation for naturally occurring prenylated xanthone α-mangostin and gambogic acid as inhibitors of MDM2-p53 interaction by some of us [88] and the promising growth inhibitory activity of 22 in cancer cell lines [86,87], this pyranoxanthone as well as other structure related compounds were submitted to in silico and in vitro studies in order to explore their potential as novel MDM2-p53 inhibitors.