Effects of propolis from different areas on mast cell degranulation and identification of the effective components in propolis.

Propolis is considered to down-regulate type I allergy, but the effective components of propolis remain unknown. In addition, propolis components vary depending on the area from which they are collected due to variations among wild plants in an area. Therefore, we compared the effects of water and ethanol extracts of propolis from Brazil and China on mast cell degranulation and cytokine production, thereby identifying effective components in propolis. The amount of released β-hexosaminidase via high-affinity IgE receptor I (FceRI) from rat basophilic leukemia (RBL-2H3) cells was used as an index of degranulation. All propolis extracts inhibited degranulation from antigen-stimulated RBL-2H3 cells, but the effective doses differed according to collection areas. The ethanol extract of Chinese propolis, which was the strongest inhibitor of mast cell degranulation, was divided into compounds using normal- and reversed-phase liquid chromatography. The isolated anti-allergic components were identified as chrysin, kaempferol and its derivative, and chrysin was revealed to inhibit IL-4 and MCP-1 production from antigen-stimulated RBL-2H3 cells. HPLC quantification also revealed the Brazilian propolis extract to contain only small amounts of these flavonoids, which suggested that variation in propolis components could affect anti-allergic properties.