Study On The Chemical Components,Metabolism And Antioxidant Activities Of Propolis Extracted By Different Methods

Propolis has excellent health benifits due to its high levels of flavonoids and polyphenols,which could prevent many chronic diseases including hypoimmunity,cancer,diabetes and aging process.Propolis extracted by different methods may have different chemical composition,thus affecting its biological activity.The objective of this thesis was to compare three extraction methods including ethnol,ultrasound-assisted and supercritical fluid CO₂ extraction based on their flavonoids components and antioxidant activities in vitro and in vivo,then metabolism mechanism of propolis in vivo was studied.The main results were as follows:1.Ultrasound assisted approach was used to extract flavonoids from propolis,and was optimized by RSM method.The optimal conditions were as follows:the frequency of impulse ultrasound was 20 k Hz,extraction time was 18 min,ultrasound power was 100 W,duty cycle was 75%,liquid height was 4 cm,and obtained maxim total flavonoids contents of propolis were（39.06±0.48）mg/g。2.The flavonoids composition of propolis was identified by HPLC-ESI-QTOF-MS.Thirty six phenolic compounds in total were confirmed in propolis extract,and 14 phenolic acids and its derivatives were identified as caffeic acid,p-coumaric acid,ferulic acid,isoferulic acid,DMCA,caffeic acid benzyl ester,caffeic acid prenyl ester,caffeic acid phenylethyl ester,caffeic acid cinnamyl ester,p-coumaric benzyl ester,p-coumaric acid prenyl ester,p-coumaric acid phenylethyl ester,p-coumaric acid cinnamyl ester and p-methoxy cinnamic acid cinnamyl ester.Twinty two flavonoids and its derivatives were identified as Chrysin-5-methyl-ether,Pinobanksin-5-methyl-ether,Quercetin,Pinobanksin,Quercetin-3-methyl-ether,Kaempferol,Apigenin,Isorhamnetin,Luteolin-methyl-ether,Dimethyl-quercetin,Kaempferol-dimethyl-ether,Quercetin-7-methyl-ether,Pinocembrin,Pinobanksin-3-O-acetate,Chrysin,Galangin,Kaempferide,Galangin-5-methyl-ether,Pinobanksin-3-O-propionate,Pinobanksin-3-O-butyrate,Pinobanksin-3-O-pentanoate,Pinobanksin-3-O-hexanoate.Phenolic compounds in propolis extracted by three methods were quantified by HPLC,and determination of their metabolits in urine and plasma of rats after gavage of propolis extracts.All samples extracted by three methods showed similar phytochemical profiles,and ultrasound assited method extracted highest concentrations of total and individual phenolics from propolis,followed by ethnol extraction.Super critical fluid CO₂extracted lowest phenolic contents.3.Antioxidant activities in vitro and in vivo of propolis extracts were examined in the present study.The results indicated that both ethnol extraction and ultrasound assited extraction displayed siminar antioxidant activities in vitro and in vivo,whereas the sample extracted by super critical CO₂ showed limited antioxidant activity in vitro and in vivo.After determination of metabolits in collected urine and blood samples of rat,we found that of the flavonoids in propolis were metabolized manily through glucuronidation and sulfation pathway.