Studies On The Main Chemical Constituents Of Qingqiao And Laoqiao,and The Activity Of Phillyrin And Forsythiaside A

Objective:To compare the differences between Qingqiao and Laoqiao by determining the main chemical constituents, including flavonoids, forsythint,forsythiaside,rutin and quercetin. To provide experimental evidence in the application of pharmaceutical, healthcare and clinicaluse. To studie the chemical constituents and antibacterial activity of Qingqiao’ n-butanol fraction and screen more active ingredients, in order to provide a reference for further exploitation and utilization on Qingqiao and Laoqiao.Methods: The total flavonoids was determined by UV spectrophotometer.Colordeveloping agent was 5% aluminum chloride. The reference was rutin.Forsythin, forsythiaside A, rutin and quercetin from qingqiao and laoqiao were determined by HPLC. This method was stable and feasible.The n-butanol fraction of Qingqiao was isolated and purified by means of silica gel column chromatography and recrystallization,etc.The structures of compounds were identified on the basis of chemical and spectroscopic methods. The antibacterial activity from the n-butanol fraction of Qingqiao were tested against Escherichia coli,Staphylococcus aureus and Streptococcus pneumoniae by using K-B paper disk method.DPPH assay was employed to assess the antioxidant activity.Results: The comparative study of the chemical composition of the experimental results showed the total flavonoids content of Qingqiao was 1.362 percent, forsythin was 29.95 ± 0.06 mg/g, forsythiaside A was 64.0325 ± 0.03 mg/g, rutin was2.6075 ± 0.02 mg/g, and quercetin was almost 0 mg/g. The total flavonoids content of Laoqiao was 1.099 percent, forsythin was 22.975 ± 0.04 mg/g,forsythiaside A was 58.3325 ± 0.03 mg/g, rutin was 0.57075 ± 0.01mg/g, and quercetin was almost 0.0209 ± 0.07mg/g. Three compounds were obtained from Qingqiao’ n-butanol fraction. Fr D-1 was identified as Forsythin. Fr D-3was identified as forsythiaside A, Fr D-2 was identified as Oleanolic acid. The diameter of inhibition zone forming by forsythiaside A against E.coli,S.pneumoniae and S.aureus were 12.35,9.58,12.29 mm,respectively. The diameter of inhibition zone forming by n-butanol fraction against E.coli,S.pneumoniae and S.aureus were 6.30,0,7.22 mm,respectively.The diameter of inhibition zone forming by Oleanolic acid against E.coli, S.pneumoniae and S.aureus were 6.30,0,7.22 mm, respectively. DPPH experimental results showed that forsythiaside A and n-butanol fraction had higher free DPPH radical scavenging capacity than forsythin. Forsythiaside A was only about 85% of ascorbic acid, n-butanol fraction was only about 63% of ascorbic acid,Forsythin was only about 0.45% of ascorbic acid.Conclusion:The comparative study of the chemical composition of Qingqiao and Laoqiao showed that the total flavonoids content, forsythiaside, forsythia, rutin content of Qingqiao were higher than that of Laoqiao, but the quercetin content of Qingqiao was less than Laoqiao. Three compounds were obtained from the the n-butanol fraction of Qingqiao. Fr D-1 was identified as Forsythin. Fr D-3 was identified as forsythiaside A, Fr D-2 was identified as Oleanolic acid. The content of Forsythiaside A was less than that of forsythin. The result was consistent withthe first part of the assay results coincide. The antibacterial test in vitro revealed that forsythiaside A showed strongest antibacterial activity and phillyrin was the weakest one. Meanwhile, forsythiaside A was more potent against Escherichia coli than other two strains. What’s more, DPPH Experimental results showed that forsythiaside A had higher free DPPH radical scavenging capacity, followed by the n-butanol fraction of Qingqiao,phillyrin had the lowest free DPPH radical scavenging capacity. compared with phillyrin, forsythiaside A had a higher antibacterial activity and antioxidant activity in vitro.