Effect of Ethanol/Water Solvents on Phenolic Profiles and Antioxidant Properties of Beijing Propolis Extracts.
Propolis is a natural substance known to be beneficial for human health and used as a folk medicine in many parts of the world. In this study, phenolic profiles and antioxidant properties of Beijing propolis extracted by different ethanol/water solvents were analyzed. Our results reveal that phenolic compounds and antioxidant properties of propolis extracts were significantly dependent on the concentration of ethanol/water solvents. Totally, 29 phenolic compounds were identified: 12 phenolic acids, 13 flavonoids, and 4 phenolic acid esters. In particular, 75 wt.% ethanol/water solvent may be the best for the highest extraction yield and the strongest antioxidant properties. Caffeic acid, benzyl caffeate, phenethyl caffeate, 5-methoxy pinobanksin, pinobanksin, pinocembrin, pinobanksin-3-O-acetate, chrysin, and galangin were the characteristic compounds of Beijing propolis, and these compounds seem to verify that Beijing propolis may be poplar-type propolis. In addition, the presence of high level of pinobanksin-3-O-acetate in Chinese propolis may be a novel finding, representing one-third of all phenolics.
Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China.
Chunli
C
Sun
Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China.
Zhengshuang
Z
Wu
Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China ; College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China.
Ziyan
Z
Wang
Institute of Apicultural Research, Chinese Academy of Agricultural Sciences, Beijing 100093, China ; National Research Center of Bee Product Processing, Ministry of Agriculture, Beijing 100093, China.
Hongcheng
H
Zhang