Phenolic compounds and antioxidant activities of edible flowers of Pyrus pashia

Pyrus pashia flowers are used as edible and medicinal materials in Yunnan Province, China. The antioxidant activities of 85% ethanolic extract of P. pashia flowers and derived soluble fractions were evaluated for the first time using four different test systems. The total phenolic and total flavonoid contents of each fraction were also determined. It was found that the ethyl acetate fraction exhibited the strongest antioxidant effect. An investigation of this flower's chemical constituents was carried out and led to the isolation of a new phenolic glycoside, 4-O-Z-coumaroylarbutin (1), along with twenty-seven other phenolic compounds (2-28). Hydroquinone (13) showed the highest content and powerful activity, which implied that the compound plays an important role in the antioxidant activity of this flower. Thus, P. pashia flowers could serve as a valuable natural antioxidant source for potential application in functional foods.