Enhanced intracellular uptake and stability of umbelliferone in compound mixtures from Angelica gigas in vitro.

Understanding how natural compounds work together for disease treatments can improve their clinical efficacy and therapeutic effects. To elucidate the mechanisms of synergistic biological effects in natural compound mixtures, umbelliferone (UMB, 7-hydroxycoumarin), derived from Angelica (A.) gigas, was selected as active compound with fluorescent characteristic to examine bioactivities in vitro in the presence of other compounds from Angelica gigas. Antioxidant effects of UMB in biochemical assays and cellular reactive oxygen species (ROS) levels in RAW264.7 cells were not significantly improved by addition of other compounds. However, intracellular uptake, inhibition of the efflux pump P-glycoprotein (P-gp), and physiological stability of UMB were greatly enhanced by the addition of other compounds, specifically Angelicin (ANG) and Byakangelicin (BYN). Taken together, enhanced intracellular localization and enzymatic stability in compound mixtures might lead to superior synergistic bioactivity of UMBs in compound mixtures.