Studies On The Antimicrobial And Antioxidant Activity Of The Extracts And Main Flavonoids And The Derivatives From Ampelopsis Grossedentata

The antimicrobial and antioxidant capacities of extracts of seventeen Ampelopsis grossedentata samples with different content of dihydromyricetin(DMY) and the main flavonoids and derivatives of flavonoids were studied.The extracts were prepared from leaves of A. grossedentata under ultrasonic wave-assisted ethanol extraction;the inhibition zone method was used to study the antibacterial activity of extracts, and compared with DMY. The DPPH· and ·OH and O2-· radical scavenging effect of samples was investigated using UV spectrophotometer method. and compared with the antioxidant activity of Vc.Experimental results are summarized as follows:1. The antimicrobial and antioxidant capacity of extracts of seventeen Ampelopsis grossedentata samples:Results showed that all of these extracts had antimicrobial and antioxidant capacity, and the activities were enhanced with the increasing of DMY content in the extracts. The antimicrobial and antioxidant capacity of extracts were significantly stronger than the contented DMY. For the same concentration, some of the extracts expressed greater antimicrobial and antioxidant capacity than DMY.In DPPH· system, DMY exerted the strongest activity, followed by Sample 10 ~ 17, Vc and BHT, and compared with BHT, Sample 2~17 exerted greater DPPH·scavenging capability. The scavenging ·OH capability:Myricetin>DMY>Vc>Extracts.The scavenging O2-· capability: DMY> Extracts> myricetin> Vc.2. Results of antimicrobial and antioxidant capacity of 9 kinds of flavonoids:9 kinds of flavonoids all had antibacterial effect on five kinds of bacteria, and with the increasing concentration of the sample antibacterial capacity enhancemented.2.1 The minimum inhibitory concentration(MIC):Antibacterial activity of kaempferol was strongest against Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli,the minimum inhibitory concentrations were greater than 0.125mg/m L, less than 0.0625mg/m L and less than 0.015625mg/m L; Myricetin and quercetin minimum inhibitory concentration of Pseudomonas aeruginosa less than 0.0625mg/m L; the minimum inhibitory concentration of Kaempferol, rutin, quercetin on Bacillus subtilis less than 0.125 mg /m L.2.2 The minimum bactericidal concentration(MBC):Minimum bactericidal concentration of Taxifolin on S. aureus was less than 0.25 mg / m L; Minimum bactericidal concentration of Myricetin on Staphylococcus epidermidis was less than 0.25 mg / m L; Minimum bactericidal concentration of kaempferol on E. coli was greater than 0.0625 mg / m L; Minimum bactericidal concentration of DMY, myricetin, quercetin on Pseudomonas aeruginosa was less than 0.125 mg / m L; Minimum bactericidal concentration of quercetin on Bacillus subtilis is less than 0.25 mg / m L.2.3 The scavenging efect of nine kinds of flavonoids on three radicals:9 kinds of flavonoids all have strong scavenging effect on the three kinds of radicals,as the concentration increases clearance capacity enhancemented.The scavenging capacity on DPPH: Myricetin> DMY> quercetin> Vc> kaempferol> Taxifolin> rutin> Hesperetin> naringenin> apigenin. Apigenin at less than 10μg/m L concentration had no scavenging effect on DPPH, naringenin at less than 6μg/m L had no scavenging effect on DPPH.The scavenging capacity on ·OH : Myricetin> kaempferol> apigenin>DMY>Vc>Taxifolin>naringenin> quercetin> rutin> hesperetin. The scavenging capacity on O2-· : DMY>naringenin>Taxifolin> Myricetin> Vc> quercetin.The four kinds of remain were that hesperetin, apigenin, kaempferol and rutin had no scavenging capacity on O2-·at the concentration range.3.The antibacterial results of Ampelopsis grossedentata extracts and DMY and myricetin derivatives :Extracts acetylation,According to the results that after acetylation the antibacterial activity of extracts were not significantly enhanced.Susceptibility measurement method using filter paper extracts methylation antibacterial activity is not obvious, and can not formed a complete inhibition zone,the results can not be accurately measured.The results showed that the acetylated products of Dihydromyricetin and Myricetin had strong antibacterial activity against four kinds of bacteria when their concentration were 4mg/m L, 2mg/m L, 1mg/m L. The minimal inhibitory concentration of dihydromyricetin, 3,3’,4’,5’-tetraethyl-dihydromyricetin, 3,3’,4’,5’,7-pentaethyl-dihydromyricetin,hexaethyl-dihydromyricetin, myricetin, 3,3’,4’,5’-tetraethyl-myricetin, 3,3’,4’,5’,7-pentaethyl-myricetin, hexaethyl-myricetin against Staphylococcus aureus were 125, 125, 125, 250, 62.5, 125, 125, 125 mg/m L; The minimal inhibitory concentration against E.Coli were 250, 125, 250, 250, 62.5, 62.5, 125, 250 mg / m L; The minimal inhibitory concentration against Staphylococcus epidermidis were 62.5, 125, 62.5, 125, 62.5, 62.5, 62.5, 125 mg/m L; The minimal inhibitory concentration against Pseudomonas aeruginosa were 250, 250, 250, 250, 125, 250, 250, 500 mg / m L.