Terpenes and sterols from the fruits of Prunus mume and their inhibitory effects on osteoclast differentiation by suppressing tartrate-resistant acid phosphatase activity

The fruits of Prunus mume are a common commercial product and a valuable source of food and medicinal material in Eastern Asian countries. Our phytochemical investigation of the P. mume fruit led to the isolation of nine terpenes, including three ursane-type triterpenes (1–3), two cycloartane-type triterpenes (4 and 5), and four tocopherols (10–13), as well as four sterols (6–9). Their structures were elucidated based on extensive spectroscopic analysis, including 1D and 2D NMR and ESI-MS, and the majority of these compounds were isolated from this plant for the first time. The anti-osteoporosis activities of 1–13 were evaluated by measuring their inhibitory effects on tartrate-resistant acid phosphatase (TRAP) activity in receptor activator of nuclear factor κB ligand-induced osteoclastic RAW 264.7 macrophage cells. Compounds 2–7 and 9–12 significantly suppressed TRAP activity down to 47.96 ± 2.45–86.45 ± 3.07 % relative to the control at a concentration of 1 μM. These results suggest that the fruits of P. mume could be an excellent source of anti-osteoporosis phytochemicals that may be developed as natural nutraceuticals and functional foods.