Triterpenoic Acids from Apple Pomace Enhance the Activity of the Endothelial Nitric Oxide Synthase (eNOS)
Katharina Waldbauer, Günter Seiringer, Dieu Linh Nguyen, Johannes Winkler, Michael Blaschke, Ruxandra McKinnon, Ernst Urban, Angela Ladurner, Verena M. Dirsch, Martin Zehl, Brigitte Kopp
Journal of Agricultural and Food Chemistry
Pomace is an easy-accessible raw material for the isolation of fruit-derived compounds. Fruit consumption is associated with health-promoting effects, such as the prevention of cardiovascular disease. Increased vascular nitric oxide (NO) bioavailability, for example, due to an enhanced endothelial nitric oxide synthase (eNOS) activity, could be one molecular mechanism mediating this effect. To identify compounds from apple (Malus domestica Borkh.) pomace that have the potential to amplify NO bioavailability via eNOS activation, a bioassay-guided fractionation of the methanol/water (70:30) extract has been performed using the 14C-l-arginine to 14C-l-citrulline conversion assay (ACCA) in the human endothelium-derived cell line EA.hy926. Phytochemical characterization of the active fractions was performed using the spectrophotometric assessment of the total phenolic content, as well as TLC, HPLC-DAD-ELSD, and HPLC-MS analyses. Eleven triterpenoic acids, of which one is a newly discovered compound, were identified as the main constituents in the most active fraction, accompanied by only minor contents of phenolic compounds. When tested individually, none of the tested compounds exhibited significant eNOS activation. Nevertheless, cell stimulation with the reconstituted compound mixture restored eNOS activation, validating the potential of apple pomace as a source of bioactive components.
Circular dichroism, Agricultural and environmental, Chemical stability, Food science