Studies On Chemical Constituents Of Zhejiang Propolis

Propolis is a natural resinous hive product collected by honeybees from leaf buds and exudates of various plant sources. It is a traditional remedy in folk medicine with several biological and pharmacological activities such as antibacterial, anti-inflammatory, antioxidant, antitumor and antiradiation properties. Researches indicate that the main active constituents of propolis are flavanoids, phenolic acids and their esters. This paper was carried out to investigate the chemical compositions and their quantitive analytical methods of propolis collected from Zhe Jiang province for the first time.Essentail oil is collected by steam distillation and the compositions are analyzed by GC-GC-MS spectroscopy techniques.Propolis sample is extracted with 95% ethanol at 80℃. The extract is concentrated under reduced pressure, separated and purified by various means, including solvent partition, silica gel column chromatography, thin-layer chromatography and recrystallization. Twelve compounds are obtained and their structures are elucidated on the basis of the data of IR,UV,MS, 1D-NMR, 2D-NMR and physical properties. Seven of them are flavanoids: Pinostrobin(Ⅰ), tectochrysin(Ⅱ), chrysin(Ⅲ), galangin(Ⅳ), pinobanksin 3-O-acetate(Ⅴ), apigenin(Ⅷ), izalpinin(Ⅸ). Three are caffeic acid analogues:3,4-dimethoxy-cinnamic acid(Ⅹ) ferulic acid (Ⅺ)caffeic acid (Ⅻ);and two are caffeic esters: Caffeic acid benzyl ester (Ⅵ), Caffeic acid phenylethyl ester (CAPE)(Ⅶ). CompoundsⅤ,compoundⅥand compoundⅦ, are isolated from Chinese propolis for the first time.HPLC quantitive analytical method of flavanoids in the propolis is established, chrysin as the reference compound. The content of chrysin and galangin are 2.89% and 2.95%, respectively. The results are in accordance with the requirements of propolis constituents in Chinese Pharmacopoeia (the contents of chrysin and galangin are no less than 2% and 1% respectively). This work provides a basis for the further isolation and application of propolis.