Design and synthesis of gambogic acid analogs as potent cytotoxic and anti-inflammatory agents

Two pyranoxanthones (16 and 20) showed the greatest activity against the KBvin multidrug resistant (MDR) cell line with IC50 values of 0.9 and 0.8 μg/mL, respectively. An angular 3-methyl-3-prenyl pyranoxanthone (17) selectively inhibited elastase release with 200 times more potency than PMSF, the positive control.