Study On Purification,Activity And Compositions Of Crude Extracts From Raspberry Dry Fruit

Raspberry(Rubus idaeus)belongs to small perennial shrubs,both have characters of tree and grass.Because nutrients and bioactive compounds of fruits are numerous,americans named raspberry "the fruit of life".In this study,crude extracts from raspberry dry fruit were purified by macroporous adsorption resin;the combination of extracts and antibiotics against bacterias were researched;investigated total ployphenols,total flavonoids of samples under water,boiling(in water),ethanol and high temperature-high pressure(in water)conditions;identified the main flavonoid compositions and concrete content changes by high performance liquid chromatography(HPLC);analyzed antioxidant activity and antibacterial activity of samples under water and high temperature-high pressure(HTHP)conditions.The results showed that:Firstly,through static-adsorption and desorption experiments,the XDA-6 was considered to be the optimum resin to purify the crude extracts of raspberry with adsorption rate(83.7%)and desorption rate(83.0%);by combining the static and dynamic experiments of resin adsorption-desorption,the optimum purification process was as follows: crude extracts solution as sample with 6 BV/h loading velocity(adsorption concentration of macroporous resin was 14.50 mg/m L),60% ethanol as elution agent with 4 BV/h elution velocity,and 5 BV elution volume.The content of purification by the process was 35.8%,which was 1.21 times more than that of crude extracts(we named “raspberry unpurified extracts” as “RUE”,“raspberry purified extracts” as “RPE” in the next part).The minimum inhibitory concentration(MIC)of Escherichia coli and Staphylococcus aureus dropped to purified solution concentration of 2 mg/mL from unpurified solution concentration of 8 mg/mL.The differences of hyphae inhibition rate of Fusarium oxyspo-rum f.sp.Vasinfectum and Fusarium gramin-earum were higher under low concentrations than under highconcentrations,but the increased inhibition efficiency of fungal hyphae is much lower than bacteria.Secondly,in all combinations of the extracts and antibiotics,synergy or partial synergy effects(FICI < 0.8)was observed.The combination of ampicillin and extracts has partial synergy effect against S.aureus and E.coil,a significant synergy effect against S.enterica for ampicillin dropped 10 times.But erythromycin has a complete reverse result with ampicillin.The combination of tetracycline hydrochloride or streptomycin sulfate with extracts both have a significant synergy effect against three bacterias,FICI<0.25,the lowest is 0.1.Thirdly,total ployphenols and total flavonoids content of samples under four conditions ranged as: HTHP>boiling>ethanol>water,RPE had a more obvious change.The total polyphenol of RUE and RPE reached 331.2 mg/g and 395.82 mg/g respectively,and increased 50.21% and 67.07% than that in water solution;Similarly,total flavonoids reached73.23 mg and 166.73 mg respectively,and increased 38.72% and 86.92% than that in water solution.The chemical components of samples mainly contain Vitamin C and catechin,little quercetin and rutin,kaempferol was below detection.After HTHP,RUE and RPE respectively had follow changes: vitamin C decreased 18.45 mg/g(27.26%),34.24 mg/g(35.20%);catechin increased 9.29 mg/g(12.54%),56.53 mg/g(59.02%);rutin decreased 0.2mg/g(57.14%),0.25 mg/g(22.32%);quercetin and other uncharted peakes had tiny changes.Fourthly,antioxidant activity of samples decreased after HTHP.By DPPH radical-scavenging assay,IC50 values of RUE increased from 28.36 μg/mL to 38.91 μg/mL;IC50 values of RPE increased from 22.93 μg/m L to 35.84 μg/m L.By ABTS radical-scavenging assay,IC50 values of RUE increased from 14.07 μg/m L to 21.46 μg/m L,IC50 values of RPE increased from 10.29 μg/m L to 21.3 μg/m L.Both above results showed that samples’ antioxidant activity decreased,the lowest one even exceed 50%.The antibacterial activity of samples significantly increased after HTHP.For RUE after HTHP,the antibacterial rate against E.coil increased about 10%;it completely inhibited S.enterica in 2 mg/m L and antibacterial rate increased from 83.6% to 100%;the antibacterial rate against S.aureus increased from 62.3% to 100%,increased 60.5%.For RPE after HTHP,the antibacterial rate against E.coil increased about 20%;it completely inhibit S.enterica and S.aureus in 1 mg/mL,increased 138% and 100% respectively.Above all,purification and HTHP both increased the content of total ployphenols and total flavonoids of extracts,improved the antibacterial activity,showed that thermal processing for raspberry extracts is not only useful for saving but for enrichment of phenols.The combination of extracts and antibiotics against bacterias can reduce the dosage of antibiotics,supply a new idea to solve problem of the abused antibiotics.