葛根提取的外文文献Word文件下载.docx
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葛根提取的外文文献Word文件下载.docx
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∙SufangHana,
∙PingyuWana,
∙MaohongFanc,
∙aBeijingUniversityofChemicalTechnology,Beijing100029,China
∙bGeneralHospitalofChinaNationalCoalGroupCorp.,Beijing110013,China
∙cSchoolofMaterialsScienceandEngineering,GeorgiaInstituteofTechnology,Atlanta,GA30332-0245,USA
∙Received24December2006.Revised30September2007.Accepted12December2007.Availableonline11January2008.
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Abstract
ThisstudyproposesanewmethodtoquicklyextractanddryisoflavonoidsfromPuerariaLobataOhwi(Pueraria)bycombiningultrasoundandmicrowavetechnologies.Thetimerequiredtoextractisoflavonoidsatcomparablelevelsofproductionbyultrasounddisruptionwas20timesshorterthanbyconventionalrefluxextraction.Moreover,testresultsfordryingtheextractedsubstancefromPuerariashowthatthemicrowave-vacuummethodis10timesfasterthantheconventionaltwo-stepvacuumapproach.Finally,differentinstrumentalanalysesofisoflavonoidsobtainedfromPuerariausingtheproposednewmethodshowthatextractionbyultrasounddisruptionandmicrowave-vacuumdryingaffectsneitherthestructurenorthecompositionoftheextractedsubstance.
Keywords:
Extraction;
Isoflavonoids;
Microwavedrying;
Ultrasound
1.Introduction
Ultrasoundhasbeenusedtoextractcompoundsfromthevariouspartsofplantsformorethanthreedecades[1].Duetothedisruptionofcellwallsandenhancedmasstransferofcellcontents,ultrasoundisabletoacceleratetheextractionoforganiccompoundsfromthebodiesofplants[2]
and
[3].Comparedwithconventionalsolventextraction,theuseofultrasoundmakestheextractionofvaluablecompoundsmoreefficientbymeansofshortertimeframesandlowerextractiontemperatures.Ultrasoundiscurrentlyemployedtoextractsuchpharmacologicallyactivecompoundsaspolysaccharides,cellulose,flavonoids,saturatedhydrocarbons,fattyacidesters,andsteroidsfromplantmaterials[4].
Microwavedryingisoftenusedtoevaporatewaterinwood,foodstuffs,drugs,andores,amongothercommodities[5]
[6];
itcanalsobeusedfordistillation[7]andextraction[8],[9]
[10].Combiningtheapplicationofmicrowaveswithvacuumtechniquesfordryingofferstwomajoradvantages,namely,rapiddryingduetotheabilityofmicrowavestoheatsolventsinstantaneouslyandhomogeneously,andenhancedrateandextentofmasstransferatsub-atmosphericpressureandlowtemperatures,whichisessentialforthermo-labileproducts.Suchdryingtechnologiesarethereforeimportantforindustriessuchaspharmaceuticals[11].
ThepresentstudyoftheextractionofisoflavonoidsfromPuerariabyultrasounddisruption,togetherwiththeirdryingbymeansofcombinedmicrowaveandvacuumtechnologies,offersanalternativetoconventionaltechnologiesforextractinganddryingisoflavonoidsfromPueraria.
2.Experimental
2.1.Plantmaterialsandchemicals
PuerariacollectedinChina'
sHenanprovincewaswashed,dried,andcutinto5
mmsegments.ThestandardsampleofPuerarinwassuppliedbyChina'
sNationalInstitutefortheControlofPharmaceuticalandBiologicalProducts.Analyticalreagent-gradeethanolandethylacetatewereusedinallexperiments.
2.2.Extraction
Fig.1showsthecombinedmicrowave-ultrasoundexperimentalsetupusedforextraction.Theapparatusconsistsmainlyofanextractioncomponent(a),amicrowavedryingcomponent(b)andasolventrecyclingcomponent(c).UltrasoundextractionwascarriedoutusingaCF-152050
kHz1200
Wultrasounddisintegrator.AGALANZWP700L17microwaveovenwithaTeflon®
evaporatingdishwasusedfordrying.
Fig.1.
Schematicdrawingoftheapparatususedforextraction(a:
extractingpart;
b:
microwavedryingpart;
c:
solventrecyclingpart;
1:
bracket;
2:
ultrasoundtransducer;
3:
beaker;
4:
sealinggasket;
5:
teflonevaporatingdish;
6:
turningplate;
7:
microwaveoven;
8:
teflontube;
9:
latextube;
10:
inlet;
11:
outlet;
12:
vacuumsucker).Viewthumbnailimages
TwentygramsofPuerariawereputintoa1000
mlbeakerforultrasoundextraction.After400
mlof70%ethanoladded,thebeakerwasputontheultrasounddisintegrator,followedbyextractionundertheultrasoundhornfor30
minatroomtemperature.SamplestakenperiodicallywereanalyzedusinganUV-2102PCUltraviolet–Visible(UV–VIS)spectrophotometer.
Arefluxextractionexperimentwasalsoperformedforpurposesofcomparison.After20
gofPuerariaweretransferredintoa1000
mlthree-neckflask,400
mlof70%ethanolwasadded.Themixturewasstirredat600
rpmandrefluxedfor120
min,
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