Syntheses of tanshinone anhydrides and their suppression on oxidized LDL uptake in macrophages and foam cell formation.

We synthesized eight tanshinone anhydrides and the alcoholytic derivatives through a mild oxygen-insertion under Pd/C catalytic hydrogenation conditions. The suppressive effects of the anhydrides on the oxidized low-density lipoprotein (oxLDL) uptake and the oxLDL-induced macrophage-derived foam cell formation were studied. Our results revealed that both anhydrides 1a and 2a could significantly suppress the oxLDL uptake in macrophages and the foam cell formation at micromolar level, which might be partially attributed to their inhibition of oxLDL-induced LOX-1 expression in macrophages.