Abstract:The content and composition of free and bound phenolic acids in rose bee pollen were studied in this paper. Their antioxidant activity was evaluated by three models: ferric reducing ability of plasma (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging capacities. Their inhibitory effects on mushroom tyrosinase activity were also determined, and their effects on cell proliferation, melanin content, and tyrosinase activity in B16 melanoma cells were studied. The content of free and bound total phenolics in rose bee pollen were 23.36 mg GAE/g dry weight (DW) and 1.47 mg GAE/g DW, respectively, and the content of free and bound total flavonoid were 19.12 and 2.42 mg RE/g DW, respectively. The phenolic compounds existed mainly in the free form, with high levels of quercetin and rutin. The content of ellagic acid and 3,4-dimethoxybenzoic acid were relatively high in the bound extract of rose pollen. Both free and bound polyphenolics showed good antioxidant activities in three models, and the half maximal inhibitory concentration (IC50) values against mushroom tyrosinase inhibitory activity were 26.34 μg/mL and 22.26 μg/mL, respectively, which were significantly better than that of Vc. Rose bee pollen phenolic extract also affected the cell proliferation and morphology of B16 cells to some extent, and pronouncedly reduced the relative melanin content and tyrosinase activity in B16 cells. The activities of different forms of phenolic extract from rose bee pollen were obviously related to the phenolic composition and content.
