Fruits from Rosa roxburghii: A Valuable Bioresource of Potent Radical Scavengers and Novel Ursane-Type Triterpenoids

Four new ursane-type triterpenoids named rosaroxine A–D and 21 known compounds were identified from Rosa roxburghii fruits. The structures of all compounds were established by 1D and 2D NMR spectroscopy and mass spectrometry. The phenolics catechin (EC₅₀ 13.4 μM), quercetin (13.1 μM), gallic acid (10.0 μM), and protocatechuic acid (15.2 μM) were identified as powerful in vitro antioxidants with EC₅₀ values lower than ascorbic acid (31.3 μM). The triterpenoids rosaroxine C (EC₅₀ 37.4; 40.3 μM) and 2-oxo-pomolic acid (16.6; 28.2) and the phenolics catechin (53.3; 29.0), quercetin (18.8; 33.1), and gallic acid (26.3; 40.0) exerted partly higher activities in the cyclo-oxygenase (COX 1/2) assay than the positive control acetaminophen (EC₅₀ 45.0; >100 μM). The triterpenoids rosaroxine C and 2-oxo-pomolic acid also performed well in the anti-aging assay using HaCaT cells. Quantification of the bioactive compounds by LC-MS revealed concentrations of 3.08 mg kg^–1 rosaroxine C, 17.40 mg kg^–1 2-oxo-pomolic acid, 76.29 mg kg^–1 catechin, and 5.58 mg kg^–1 protocatechuic acid in the dried fruits. Overall, this work provides detailed phytochemical information, and the results from the accomplished bioassay point toward health promoting properties of these fruits.