Roxbugalloylacid A and B: Two New Galloyl Glucosides With Antioxidant Activity From the Leaves of Rosa roxburghii

Phytochemical investigation of Rosa roxburghii leaves resulted in the isolation of five compounds, including two new galloyl glucosides, roxbugalloylacid A and B (1 and 2), along with three known ones. The structures of all isolated compounds were determined by 1D and 2D NMR experiments and by comparison of their spectroscopic and physical data with literature values. Compounds (1-5) exhibited better in vitro ABTS radical-scavenging activity with IC₅₀ values ranging from 6.1 ± 2.9 to 21.9 ± 0.2 µM than ascorbic acid with IC₅₀ value of 37.4 ± 0.7 µM. Compounds (1, 3-5) exhibited moderate DPPH radical-scavenging activity with IC₅₀ values ranging from 95.9 ± 4.6 to 196.9 ± 8.2 µM. Furthermore, a model of H₂O₂-induced oxidative damage in RAW264.7 cells was established to analyze the antioxidant effect of isolated compounds. The levels and activities of MDA, GSH, SOD, and CAT were determined by enzyme linked immunosorbent assay (ELISA). Compounds (1 and 2) significantly decreased the level of MDA and increased GSH activity. While compounds (3 and 5) significantly increased activities of GSH, SOD, and CAT. In summary, compounds (1-5) demonstrate antioxidant activities that alleviate H₂O₂-induced RAW264.7 cell damage.