Characterization of flavonoids in the traditional Chinese herbal

Journal of Chromatography B,848(2007)

355–362

Characterization of?avonoids in the traditional Chinese herbal medicine-Huangqin by liquid chromatography coupled

with electrospray ionization mass spectrometry

Jian Han,Min Ye1,Man Xu,Jianghao Sun,Baorong Wang,Dean Guo?

The State Key Laboratory of Natural and Biomimetic Drugs,School of Pharmaceutical Sciences,

Peking University,Xueyuan Road38,Beijing100083,China

Received2August2006;accepted29October2006

Available online21November2006

Abstract

The root of Scutellaria baicalensis,called Huangqin in Chinese,is one of the most commonly used traditional Chinese medicines for the treatment of hepatitis,tumors,diarrhea,and in?ammatory diseases.The major chemical constituents of Huangqin are?avonoids.In the present paper,HPLC-DAD-ESI-MS n was used to analyze?avonoids in the roots of S.baicalensis.A total of26?avonoids were identi?ed or tentatively characterized,including5C-glycosides,12O-glycosides,and9free aglycones.Two C-glycosides,apigenin-6-C-glucyl-8-C-arabinoside and chrysin-6,8-di-C-glucoside,together with some O-glycosides,are reported from S.baicalensis for the?rst time.This method is simple,reliable and sensitive,and could be used for the quality control of Huangqin and its related preparations.

?2006Elsevier B.V.All rights reserved.

Keywords:Huangqin;Flavonoids;HPLC/DAD/ESI-MS n;Chinese medicine

1.Introduction

Huangqin(Radix Scutellariae)is an important traditional Chinese medicine prepared from the roots of Scutellaria baicalensis Georgi(Labiatae family)[1].Traditionally,it was employed for detoxication and relief of fever.Currently, Huangqin is widely used for the treatment of various in?am-matory diseases,hepatitis,tumors and diarrhea in East Asian countries.It acts as a key ingredient in a number of formu-lae such as Shuanghuanglian oral liquid,Compound Huangqin granule,Yinhuang Tablet,etc.The chemical constituents of Huangqin have been investigated in some detail,mostly involv-ing?avonoids like baicalein,baicalin,wogonin and wogonoside. More than60?avonoids have been reported from Huangqin, and most of them occur as glucuronoids[2].These compounds showed signi?cant biological activities,and are critical for the quality control of Huangqin.

?Corresponding author.Tel.:+861082801516;fax:+861082802700.

E-mail address:gda@https://www.wendangku.net/doc/1f17402276.html,(D.Guo).

1Present address:Department of Pharmacology,School of Medicine,Yale University,New Haven,CT06520,United States.

For quality control of Huangqin,previous reports involved the analysis of few major?avonoids by HPLC coupled to UV detection.Although LC/MS has recently been used for the analysis of Huangqin,these reports only focused on known com-pounds[3,4].Little effort has been contributed to global analysis of?avonoids in S.baicalensis,especially those new minor ones.

Liquid chromatography coupled with mass spectrometry (LC/MS)is a powerful tool for the rapid identi?cation of chem-ical constituents in plant extracts.The high sensitivity of MS as an LC detector facilitates to discover new minor constituents, which are dif?cult to obtain by classical means.

The tandem mass spectrometric fragmentation behavior of ?avonoids has been investigated extensively,which allows the characterization of unknown compounds even without the refer-ence standards[5–7].A study on14?avonoids,monohydroxy-to pentahydroxy-substituted,has been carried out using HPLC-ESI-MS by Hughes et al.[8].Wu et al.[9]studied the fragmentation pathways of nine?avonoid compounds by ESI-MS and observed some diagnostic neutral losses for the identi?cation of the functional groups in the structures.Also, it was demonstrated that ions[M?H?60]?,[M?H?90]?,

1570-0232/$–see front matter?2006Elsevier B.V.All rights reserved. doi:10.1016/j.jchromb.2006.10.061

356J.Han et al./J.Chromatogr.B 848(2007)355–362

[M ?H ?120]?were characteristic for C-glycoside ?avonoids.Eleven naturally occurring ?avonoid aglycones,belonging to different types,were determined by HPLC-ESI-MS/MS [10].Kite et al.[11]described an ion trap LC–MS/MS method for the analysis of C-glycosyl?avone O-glycosides in crude methanolic extracts of plants.

In the present study,HPLC-DAD-ESI-MS n was used to ana-lyze ?avonoids in the roots of S.baicalensis .A total of 26?avonoids were identi?ed or tentatively characterized,includ-ing 5C-glycosides,12O-glycosides,and 9free aglycones.Two C-glycosides,apigenin-6-C-glucyl-8-C-arabinoside and chrysin-6,8-di-C-glucoside,together with some O-glycosides,are reported from S.baicalensis for the ?rst time.2.Experimental

2.1.Chemicals and materials

Baicalin,baicalein and wogonin were purchased from the National Institute for the Control of Pharmaceutical and Bio-logical Products (NICPBP)(Beijing,China).Their structures are shown in Fig.1.

HPLC grade acetonitrile (MeCN)(Fisher,Fair Lawn,NJ,USA)and ultra-pure water were used for all analy-ses.The methanol used for extraction of samples was AR grade,purchased from Beijing Chemical Corporation (Beijing,China).

2.2.Plant materials and samples preparation

The roots of S.baicalensis were collected from different regions around China (see Table 1)and identi?ed by the

authors.

Fig.1.Chemical structures of three standard ?avones in Scutellaria baicalensis .Table 1

The source of Radix Scutellariae

Sample number 1#

2#3#4#

5#6#Growth region

Shanxi

Shanxi

Hebei

Heilongjiang

Neimenggu

Beijing

The materials were pulverized and an aliquot of 1g was extracted with 50mL of 70%methanol aqueous solution by ultrasonica-tion for 30min and then ?ltered.The ?ltrate was evaporated to dryness and the residue was dissolved in 1mL of methanol.This solution was then ?ltered through a 0.45?m membrane before use and 10?l was injected into the HPLC instrument for analysis.

2.3.HPLC conditions

An Agilent series 1100HPLC instrument (Agilent,Wald-bronn,Germany)equipped with a quaternary pump,a diode-array detector,an autosampler and a column compartment was used for analyses.The sample was separated on a Zorbax XDB-C 18column (5?m,?4.6×250mm,Agilent).The mobile phase consisted of CH 3CN (A)and water containing 0.2%acetic acid (B).A gradient program was used as follows:20%A in the ?rst 10min,25%A at 11–25min,35%A at 26–41min,linearly gradient to 55%A at 45min,then linearly gradient to 60%A at 55min and hold for 5min.The mobile phase ?ow rate was 0.8mL/min;the chromatogram was recorded at 280nm and spectral data for all peaks were accumulated in the range of 190–400nm.Column temperature was controlled at 25?C.

2.4.Mass spectrometric conditions

A Finnigan LCQ Advantage ion trap mass spectrometer (ThermoFinnigan,San Jose,CA)was connected to the Agi-lent 1100HPLC instrument via ESI interface for HPLC/MS analysis.Ultrahigh pure helium (He)was used as the collision gas and high purity nitrogen (N 2)as the nebulizing gas.The optimized parameters in the negative ion mode were as fol-lows:ion spray voltage,4.5kV;sheath gas,40arbitrary units;auxiliary gas,15units;capillary temperature,320?C;capil-lary voltage,?5V;tube lens offset voltage,40V .For full scan MS analysis,the spectra were recorded in the range of m /z 100–1000.The isolation width of precursor ions was 3.0U.The relative collision energy was adjusted to 45%of maxi-mum.MS n data were acquired in the automatic data-dependant mode.

2.5.Method validation

The repeatability was assessed by analyzing six indepen-dently prepared samples of Huangqin.The relative standard deviation (R.S.D.)of the peak retention times for each of the main characterized ?avonoids in the extracts was calculated.

The method precision was evaluated by analyzing the same sample for ?ve consecutive times.The R.S.D.of the peak reten-tion times for each of the main characterized ?avonoids in the extracts was calculated.

The sample stability test was determined with one sam-ple during two days.In this period,the solution was stored at room temperature,and analyzed at 0,12,24and 48h,respectively.

J.Han et al./J.Chromatogr.B 848(2007)355–362

357

Table 2

MS n product ions obtained from standard ?avonoids in this study Compound [M ?H]?MS n ions m /z (%base peak)

Baicalein 269MS 2[269]:251(100),241(40),225(40),223(40);MS 3[251]:223(100)Baicalin 445MS 2[445]:269(100),175(20);MS 3[269]:251(100),241(25),225(10),223(20),197(10);MS 4[251]:223(100)

Wogonin

283

MS 2[283]:268(100);MS 3[268]:240(100),239(90),223(20),212(20),196(20),163(80)

3.Results and discussion

3.1.Tandem mass spectrometry of pure standards

Negative ion mode was selected for ESI-MS analysis in this study,as it provided extensive structural information via collision-induced dissociation (CID).Nomenclature proposed by Fabre et al.was used in this context for ?avonoid fragments [10].

ESI-MS n spectral data of baicalin,baicalein and wogonin are shown in Table 2.The [M ?H]?ion of baicalein at m /z 269produced an ion at m /z 251,which should result from the loss of H 2O.The ion at m /z 241was due to the loss of CO,and the m /z 223ion was due to the successive loss of H 2O and CO (Fig.2).Baicalin is an O-glucuronide.Upon CID,the glycosidic bond was easily cleaved to generate an ion at m /z 269,which resulted from the neutral loss of a glucuronic acid ( m =176u).In the MS 3experiment,ion at m /z 269produced the same ions as baicalein described above.

Wogonin is a methoxylated ?avone.It exhibited a sig-ni?cant radical anion [M ?H ?CH 3]??as the base peak.In MS 3spectra,we observed the signi?cant ion at m /z 239[M ?H ?CH 3???COH ?]?,and the low signal intensity ions at m /z 163(0,2A ?),212[M ?H ?CH 3??2CO]??,223[M ?H ?CH 3??CO 2H ?]?,240[M ?H ?CH 3??CO]??,which is identical with the previous report [9]

.

Fig.2.Full scan MS n spectra for Baicalein.(a)MS spectrum of the Baicalein.(b)MS 2spectrum of the [M ?H]?ion at m /z 269.(c)MS 3spectrum of the ion at m /z

251.

Fig.3.A representative HPLC-ESI-MS n analysis of the extract of Huangqin.(a)HPLC-UV c hromatogram monitored at 280nm (b)LC-negative ion ESI-MS total ion current (TIC)pro?le.

3.2.HPLC-DAD-ESI-MS n analysis of the plant extract Fig.3showed the HPLC-UV and TIC pro?les of the extract of S.baicalensis .The retention behavior of ?avonoids on the reversed-phase HPLC column was remarkably affected by the pH of the mobile phase.Therefore,water containing 0.2%(v/v)CH 3COOH was used to achieve a good base line and complete resolution of the major peaks.

The HPLC peaks were preliminary identi?ed as ?avonoids according to their on-line UV spectra.Flavonols and their gly-cosides exhibited two maximum absorptions at 330–360nm and 250–270nm,originating from their B and A rings,respectively.The structures were further characterized mainly based on their MS fragmentation behaviors (Table 3).A number of ?avonoids have been reported from S.baicalensis previously.The agly-cones belong to several subtypes,?avone,?avonol,?avanone,?avanonol,?avan and chalcone.The sugar moieties included glucose,glucuronic acid and arabinose.

3.2.1.Method validation

Considering the features of ?ngerprints,the R.S.D.of the retention times of the 26“common peaks”identi?ed in the extracts of Huangqin were used to evaluate the developed method.

The repeatability was evaluated by analyzing six indepen-dently prepared samples of Huangqin.The relative standard

358J.Han et al./J.Chromatogr.B848(2007)355–362

Table3

Characterization of?avonoids by HPLC-DAD-ESI/MS from Scutellaria baicalensis

Peak no.Retention time

(t R min)

UVλmax(nm)[M?H]?m/z HPLC-ESI-MS n m/z(%base peak)Identi?cation

1 4.14222,388577MS2[577]:487(2),457(100),415(2),295(15);MS3[457]:

295(100),337(10);MS4[295]:267(100)

Chrysin-7-O-glu-8-C-glu

2 5.47222,388563MS2[563]:545(5),503(35),473(85),443(100),383(40),

353(45);MS3[443]:353(100),383(15);MS4[353]:

325(100);MS5[325]:297(100)Apigenin-6-C-glu-8-C-ara (schaftoside)

3 6.06222,388577MS2[577]:559(10),517(5),487(35),457(100),367(15),

337(35);MS3[457]:367(10),337(100);MS4[337]:

309(100),281(25);MS5[309]:281(100)

Chrysin-6,8-di-C-glu

47.69224,272,314547MS2[547]:529(30),487(80),457(100),427(55),367(50),

337(40);MS3[457]:337(100);MS3[427]:367(10),

337(100);MS4[337]:309(100),281(20);MS5[309]:

281(100)

Chrysin-6-C-ara-8-C-glu

58.77220,290,330623MS2[623]:461(100);MS3[461]:315(90),135(100),

161(35)

Isorhamnetin-7-O-rha-glu

69.42220,274,316547MS2[547]:529(10),487(5),457(60),427(100),367(10),

337(15);MS3[457]:367(100),337(55);MS3[427]:

337(100),367(10);MS4[337]:309(100),281(10);

MS5[309]:281(100)

Chrysin-6-C-glu-8-C-ara

712.88222,264621MS2[621]:445(100);MS3[445]:430(100),283(90),

268(65);MS4[430]:267(100);MS5[267]:239(100)

Wogonin-7-O-glu-glu acid

814.39222,254,302(sh),340491MS2[491]:329(100);MS3[329]:314(100),299(10),

261(5);MS4[314]:299(100);MS5[299]:271(100),165(75)3 ,4 -Dihydroxy-5,6-dimethoxy-7-O-glucoside ?avone

915.72220,274637MS2[637]:461(100);MS3[461]:315(90),135(100),

161(80)Isorhamnetin-7-O-rha-glu acid

1016.55222,270,332951MS2[951]:475(100),299(15);MS3[475]:299(100);

MS4[299]:284(100)5,2 -Dihydroxy-6 -methoxy-7-O-glu acid

?avone

1118.57222,276,316445MS2[445]:269(100);MS3[269]:251(25),241(5),197(3)Baicalin

1220.38218,278,318431MS2[431]:269(100);MS3[269]:251,241,197Baicalein-7-O-glu

1322.75220,264447MS2[447]:271(100);MS3[71]:253(50),243(100),

227(20),199(5),167(5)5,6-Dihydroxy-7-O-glu acid ?avanone

1423.55220,280891MS2[891]:445(100),269(15);MS3[445]:241(15),

225(35),197(15),183(2);MS4[269]:239(100)

Galengin-7-O-glu acid

1524.05222,270445MS2[445]:430(100),283(95),268(75);MS3[430]:

267(100)

Wogonin-5-O-glu

1626.09218,272,312919MS2[919]:459(100),283(15),268(5);MS3[459]:

283(100),175(4);MS4[283]:268(100)

Oroxylin A-7-O-glu acid

1730.61222,272919MS2[919]:459(100);MS3[459]:283(100);MS4[283]:

268(100)

Wogonoside

1834.12226,276,294,326299MS2[299]:284(100);MS3[284]:256(10),228(20),137(5)5,7,3-Trihydroxy-4 -methoxy

?avone

1935.48220,276,322269MS2[269]:251(60),241(10),169(5)Norwogonin

2036.17220,276,322269MS2[269]:251(100),241(20),223(20),169(5)Baicalein

2137.44218,270,334299MS2[299]:284(100);MS3[284]:267(10),256(10),

166(100),138(60)5,7,4 -Trihydroxy-8-methoxy ?avone

2242.70264343MS2[343]:328(100),313(15);MS3[328]:313(100),

273(10);MS4[313]:297(10),285(100),269(10),165(15)5,2 -Dihydroxy-7,8,6 -trimethoxy?avone (Skullcap?avon I)

2343.71226,274283MS2[283]:268(100);MS3[268]:239(60),212(15),163(30)Wogonin

2444.45224,272373MS2[373]:358(100),343(25);MS3[358]:343(100);

MS4[343]:328(100),300(10),285(10),169(5);MS5[328]:

300(100),272(15),228(5)5,2 -Dihydroxy-6,7,8,6 -tetramethoxy?avone (Skullcap?avon II)

2545.42222,270,318283MS2[283]:268(100);MS3[268]:239(35),212(15),163(5)5,7-Dihydroxy-6-methoxy

?avone(Oroxylin A)

2646.87278343MS2[343]:328(100);MS3[328]:313(100);MS4[313]:

298(100),285(5),270(10)5,2 -Dihydroxy-6,7,8-trimethoxy?avone(Tenaxin I)

Note:glu:glucose,ara:arabinose,rha:rhamnose,glu acid:glucuronic acid.

J.Han et al./J.Chromatogr.B848(2007)355–362

359

Fig.4.HPLC-ESI-MS TIC pro?les of the Huangqin collected from different regions.

deviation of the retention times for each of the26“common peaks”was less than2.0%(Table A.1and Fig.4).

The method precision was measured by analyzing the same sample for?ve consecutive times.The R.S.D.of the common peak retention times were less than1.2%(Table A.2).

To test the stability of the analytes,the same sample was analyzed in two days.Peak retention time R.S.D.for all of the 26common peaks were less than1.0%(Table A.3),suggesting that the sample remained stable within2days.

All of above results of repeatability,precision and stabil-ity test indicated that this method was sensitive,reliable and applicable.

3.2.2.Identi?cation of?avone glycosides

Seventeen?avone glycosides were plausibly identi?ed. Seven of them have previously been reported from S.baicalen-sis.The other ten compounds were reported for the?rst time and were tentatively identi?ed on the basis of their tandem mass spectra.

3.2.2.1.C-glycosides.Two compounds(peaks4and6in Fig.3)in the HPLC chromatogram exhibited[M?H]?ions at m/z547.Their UV spectra showed maximum absorption bands at224,272and314(sh)nm.Their MS/MS spectra gave ions of[M?H?60]?at m/z487,[M?H?90]?at 457and[M?H?120]?at427,consistent with the char-acteristic ions of C-glycoside.It had been demonstrated that?avonoid C-6and C-8glycosides could be distin-guished by the relative abundance of ions[M?H?60]?and[M?H?120]?[12,13].Similar difference was observed for MS/MS spectra of these two compounds(Table4).

Therefore,compounds4and6were identi?ed as the

known compounds,chrysin-6-C-arabinosyl-8-C-glucoside and

chrysin-6-C-glucosyl-8-C-arabonoside,respectively[9,12].

Compound2(t R=5.47min)exhibited a[M?H]?at m/z

563,16Da greater than that of compound6.Its MS/MS spec-

trum showed ions of[M?H?60]?at m/z503,[M?H?90]?

at473and[M?H?120]?at443,which were characteristic

ions of C-glycosides demonstrated by Becchi and Fraisse[14].

The structure of compound2was proposed to be apigenin-6-C-

glucosyl-8-C-arabinoside(schaftoside).

Compound3(t R=6.06min)yielded a[M?H]?ion

at m/z577,30Da greater than that of compound 4.Its

MS/MS spectra produced prominent ions of[M?H?60]?

at m/z517,[M?H?90]?at487,[M?H?120]?at457,

[M?H?210]?at367and[M?H?240]?at337,all of which

are the characteristic ions of di-C-hexosyl?avones[15],sug-

gesting the presence of chrysin(254)+hexose(162)+hexose

(162)(MW578).In previous studies,all of the hexose moi-

ety in?avonoids in S.baicalensis were identi?ed as glucosides.

Thus,compound3was tentatively characterized as chrysin-6,8-

di-C-glucoside.

https://www.wendangku.net/doc/1f17402276.html,pound5(t R=8.77min)displayed

a[M?H]?ion at m/z623.The MS2and MS3spec-

tra gave ions at m/z461and315,suggesting sequential

losses of glucosyl(162Da)and rhamnosyl(146Da)residues.

Compound5was thus tentatively identi?ed as isorhamnetin-7-

O-rhamnosylglucoside.The signals at m/z135and161were the

ions of1,2B?and[1,2A??18]?,respectively.Alycone such as isorhamnetin was?rst reported in S.baicalensis,although it is

commonly occurred in natural?avonoids.

Compound7(t R=12.88min)gave a[M?H]?ion at m/z

621.CID of this compound produced an ion of[M?H?176]?

at m/z445,which resulted from the neutral loss of a glucuronic

acid residue.In the MS3of m/z445,fragments of m/z430and

283indicated the presence of a methoxyl group and a hexo-

syl residue,https://www.wendangku.net/doc/1f17402276.html,pound7was thus proposed as

wogonin-7-O-glucosyl-glucuronide,which was identi?ed in this

plant for the?rst time.

Compound10(t R=16.55min)exhibited[2M?H]?ion at

m/z951and[M?H]?signal at m/z475.The MS2spectrum

of m/z951produces ion at m/z475.It has been reviewed that

the peak at the highest m/z ration is not always the molecular

ion species,because molecular complexes can be generated[6].

Thus we presumed that compound10was a molecular com-

plex.The MS3spectrum of475produced base peak at m/z299,

attributed to the loss of176Da,suggesting the presence of a glu-

curonic acid.Then MS4of m/z299resulted in the ion of m/z284

(?15Da),suggesting the existence of a methoxy group.In ref-

Table4

Relative intensity of ions in ESI-MS/MS of the compounds4and6

Peak[M?H?60]?(%)[M?H?90]?(%)[M?H?120]?(%)[M?H?180]?(%)[M?H?210]?(%) 480100555040

65601001015

360J.Han et al./J.Chromatogr.B 848(2007)

355–362

Fig.5.ESI-MS spectra for compound 1:(a)MS spectrum;(b)MS 2spectrum of the [M ?H]?at m /z 577;(c)MS 3spectrum of m /z 457;(d)MS 4spectrum of m /z 295.

erence to the previous report [16],compound 10was plausibly characterized as 5,2 -dihydroxy-6 -methoxy-7-O-glucuronate ?avone.

Compound 11(t R =18.57min)represented a main constituent of S.baicalensis .It exhibited [M ?H]?ion at m /z 445,and its CID gave the ions consistent with baicalin.Thus,compound 11was identi?ed as baicalin and this identi?cation was con?rmed by comparison with a pure standard.

Compound 13(t R =22.75min)exhibited [M ?H]?ion at m /z 447.Its MS 2produced an ion at m /z 271[M ?H ?176]?,indi-cating the existence of a glucuronic acid.Its MS 3yielded ion at m /z 253,resulted from the loss of H 2O group,suggesting the presence of two OH in ortho positions.The ion at m /z 167was attributed to the 1,3A ?,proving the occurrence of three OH groups in A ring.In addition,the molecular mass of the com-pound 13was 2Da greater than baicalin,it was thus identi?ed as 5,6-dihydroxy-7-glucuronic acid ?avanone.

Compound 14(t R =23.55min)gave a [2M ?H]?ion at m /z 891,another strong peak at m /z 445[M ?H]?was also observed.The MS 2spectrum of m /z 891produced a base peak at m /z 445,thus compound 14was assumed to be a complex of ?avone,too.The MS 2spectrum of m /z 445yielded an ion at m /z 269,loss of 176Da,suggesting the presence of a glucuronic acid.The m /z 269ion was further subjected to MS 3analysis,ions of m /z 241(?28Da),225(?44Da),197(?72Da)and 183(?86Da)were observed,which were consistent with the

data of galengin reported by Fabre and Rustan [10].Accord-ingly,compound 14was tentatively identi?ed as galengin 7-O-glucuronide.

Compounds 16(t R =26.09min)and 17(t R =30.61min)are a pair of isomers.Both of them gave a [2M ?H]?ion at m /z 919and signi?cant [M ?H]?signal at m /z 459.And m /z 459gave the ion at m /z 283(?176),involving the loss of a glucuronic acid,then m /z 283yielded ion at m /z 268(?15),suggesting the presence of a –CH 3group.By examining the known ?avonoids in S.baicalensis ,there were two ?avones,named oroxylin A-7-O-glucuronide and wogonoside,consistent with the above data.According to the content difference and the retention time in HPLC reported before [17],compounds 16and 17were plausi-bly identi?ed as oroxylin A-7-O-glucuronide and wogonoside,respectively.

3.2.2.3.C-glycosyl?avone https://www.wendangku.net/doc/1f17402276.html,pound 1exhib-ited a [M ?H]?ion at m /z 577.Its MS 2spectrum (Fig.5)gave the ions at m /z 487[M ?H ?90]?and base peak 457[M ?H ?120]?,indicating that it was a C-glycoside.In the MS 2spectrum [M ?H ?60]?did not appear,thus it was con-cluded that the sugar moiety is a hexsose,but not a pentose.Interestingly,ion of [M ?H ?162]?at m /z 415,characteristic ions of O-glycoside,was also observed.Thus it was plausibly identi?ed as chrysin-7-O-glucosyl-8-C-glucoside,which was ?rstly identi?ed in Scutellaria species.

J.Han et al./J.Chromatogr.B848(2007)355–362361

3.2.3.Aglycone

Nine aglycones were characterized or tentatively charac-terized.Seven of them were known constituents previously identi?ed in S.baicalensis.

Compound18(t R=34.12min)and compound21 (t R=37.44min)are isomers,both yielding[M?H]?at m/z299.The MS of compound18indicated the existence of a–CH3group.And the ion at m/z228represented the ion of[M?H?2CO]?,which was only observed in?avonols, reported by Fabre and Rustan[10].Thus,it was tentatively identi?ed as5,7,3-trihydroxy-4 -methoxy?avone.While MS3spectrum of compound21exhibited an ion at m/z267 originated from ion at m/z284,corresponding to the loss of H2O group,which indicated the existence of two–OH groups in ortho positions.Moreover,its MS spectrum was similar to that of wogonin,only an–OH group difference. Based on these information,compound21was identi?ed as5,7,4 -trihydroxy-8-methoxy?avone,which has been identi?ed in S.baicalensis[18]and S.amoena C.H.Wright [19].

Compound19(t R=35.48min)and compound20 (t R=36.17min)both displayed the[M?H]?ion at m/z https://www.wendangku.net/doc/1f17402276.html,pared with the standard,compound20was con?rmed as baicalein.The MS fragmentation of compound19was extremely similar with that of compound20.By searching the known?avones which MW was270in S.baicalensis, compound19was tentatively characterized as norwogo-nin.

Compound22(t R=42.70min)and compound26 (t R=46.87min)both gave the[M?H]?ion at m/z343. By analyzing their CID,it was concluded that both of them contain three–OCH3groups since the ions of m/z328,313 and298have been observed.However,their MS4spectra of m/z313were signi?cantly https://www.wendangku.net/doc/1f17402276.html,pound22showed a base peak at m/z285,and the intensity of ion at m/z298was very weak;on the contrary,compound26showed base peak at m/z298and a very weak intensity at m/z285.Based on these data and by the knowledge on the?avones in S.baicalensis, compounds22and26were identi?ed as skullcap?avon I and tenaxin I,respectively.

Compound23(t R=43.71min)and compound25 (t R=45.42min)both yielded an[M?H]?ion at m/z 283.The MS fragments and retention time in HPLC of compound23were consistent with the known wogonin,and allowed its identi?cation.The MS spectra of compound25 were almost identical to those of compound23.However,its retention time supported its possible identi?cation as oroxylin A [17].

Compound24(t R=44.45min)gave the[M?H]?ion at m/z373.Its CID yielded ions at358[M?H?CH3]??,343[M?H?2CH3]?,328[M?H?3CH3]??, 300[M?H?3CH3?CO]??,285[M?H?3CH3?CO?CH3]?,272[M?H?3CH3?2CO]??and228[M?H?

3CH3?CO?CO2]??.These ions should come from four –OCH3groups and the?avone skeleton.By examining the known?avones in S.baicalensis,it was tentatively identi?ed as skullcap?avone II.4.Conclusion

In this study,a simple,reliable and sensitive method has been established for the screening of main?avonoids in S.baicalensis by HPL C-DAD-/ESI-MS https://www.wendangku.net/doc/1f17402276.html,ing negative ion mode and apply-ing the MS fragmentation rules of?avonoids reported before, 26?avonoids,involving17?avonoid glycosides and9free aglycones,were identi?ed or tentatively identi?ed in methanol extracts of S.baicalensis.Only two C-glycosides have been previously reported in S.baicalensis.However,several new analogues were identi?ed in the present study,which proved that HPLC-MS is a powerful and rapid method to discover new constituents in medicinal herbs.

The major reason that traditional Chinese medicines could not be accepted by the western world is the ambiguous chemical components of it,which limits the modernization and glob-alization of traditional medicine.Our present method could comprehensively evaluate the quality of S.baicalensis sam-ples and extracts covering most of the chemical constituents, and reduce the necessity to isolate each individual?avonoid from the herb utilizing tedious conventional phytochemical pro-cedures.It set a good example for the rapid identi?cation of bioactive constituents in plant extracts and made it possible to ful?l the requirements for a modern drug with characters of safety,ef?cacy and stability.

Appendix A

Table A.1

The retention time in HPLC-MS?ngerprints of Radix Scutellariae (repeatability)

Peak number Sample number R.S.D.(%) 1#2#3#4#5#6#

1 4.11 4.08 4.08 4.2

2 4.09 4.16 1.24

2 5.20 5.10 4.94 5.0

3 4.93 4.97 1.91

3 6.0

4 6.06 6.13 6.17 6.07 6.110.73

47.717.607.787.717.707.770.76

58.778.928.798.868.829.000.90

69.569.649.649.649.589.650.36 713.3613.4813.2613.1913.412.98 1.23 814.6414.5514.5414.6014.5914.810.62 915.7715.8415.8615.8415.8515.850.19 1016.6016.5716.7116.6616.7416.660.35 1118.8418.7718.7718.9218.9218.990.43 1220.5220.5520.5120.6320.6320.700.33 1322.7622.7622.9223.0423.0422.910.50 1423.5523.6723.3723.3923.5123.670.51 1524.0424.2524.0624.0724.3324.230.46 1626.1926.2726.2726.2726.3226.270.15 1730.5630.5930.4830.5530.4530.570.17 1834.3534.3134.2534.2634.8034.910.78 1935.6035.6435.6235.7935.7935.800.25 2036.3736.4636.4136.4536.4236.590.19 2137.5937.5637.5037.5537.6037.520.09 2242.8742.9242.9542.8442.8642.870.09 2343.9743.943.9743.8743.8744.050.15 2444.6044.7644.6644.7044.6044.690.13 2545.7945.6145.5745.6745.6545.650.15 2646.8546.8947.0346.9446.9447.100.18

362J.Han et al./J.Chromatogr.B848(2007)355–362

Table A.2

The retention time in HPLC-MS?ngerprints of Radix Scutellariae(injection precision)

Peak number Injection times R.S.D.(%) 12345

1 4.11 4.15 4.14 4.16 4.10.56

2 5.34 5.39 5.30 5.32 5.310.60

3 6.06 5.99 5.90 6.06 6.000.98

47.627.667.457.697.50 1.23

58.698.728.508.778.60 1.10

69.449.459.279.549.500.98 712.9412.9112.9913.0312.980.32 814.3414.4214.3514.3914.350.21 915.6615.6915.7115.6715.660.12 1016.5716.5116.5116.5516.520.15 1118.6518.6518.7218.6818.690.14 1220.3820.3920.2820.2720.280.26 1322.7022.7122.6922.7522.700.09 1423.5323.5623.6123.5523.600.13 1524.1924.1924.2224.1924.200.05 1626.1126.1826.2226.2126.200.15 1730.4130.4330.4730.4030.420.08 1834.1434.2434.2034.2434.200.11 1935.4835.5735.6035.5935.580.12 2036.3136.3136.3636.4236.410.13 2137.3937.3837.4037.4437.400.05 2242.6842.7942.7242.8342.800.13 2343.7743.7643.7943.8143.800.04 2444.4344.4244.5244.4544.460.08 2545.5045.5145.4345.4245.500.09 2646.9046.9146.9346.8746.890.04 Table A.3

The retention time in HPLC-MS?ngerprints of Radix Scutellariae(stability) Peak number Times R.S.D.(%) 0h12h24h48h

1 4.16 4.14 4.06 4.100.93

2 4.97 5.02 5.04 5.000.52

3 6.11 6.06 6.03 6.000.67

47.777.697.657.750.62

59.008.868.868.900.64

69.659.549.449.550.78 712.9813.0313.0912.990.33 814.8114.5414.6414.700.67 915.8515.6715.7115.680.46 1016.6616.5516.5216.550.32Table A.3(Continued)

1118.9918.6818.6518.700.73 1220.7020.3520.3820.400.69 1322.9122.8722.8022.880.18 1423.6723.5523.5323.600.23 1524.2324.3124.2724.250.12 1626.2726.2126.1326.250.20 1730.5730.4030.4430.400.23 1834.1534.1934.2434.000.26 1935.8035.4835.4835.600.37 2036.5936.3836.3236.400.28 2137.5237.4437.4437.500.10 2242.8742.8342.8142.800.06 2344.0543.9143.7944.000.22 2444.6944.4544.4344.500.23 2545.6545.4245.4145.500.21 2647.1047.0046.9547.000.12 References

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英语中的比较级与最高级 详解

比较级与最高级 1.as...as 与(not) as(so)...as as...as...句型中，as的词性 第一个as是副词，用在形容词和副词的原级前，常译为“同样地”。第二个as是连词，连接与前面句子结构相同的一个句子(相同部分常省略)，可译为“同..... He is as tall as his brother is (tall) . (后面的as 为连词) 只有在否定句中，第一个as才可换为so 改错: He is so tall as his brother.（X） 2.在比较状语从句中，主句和从句的句式结构一般是相同的 与as...as 句式中第二个as一样，than 也是连词。as和than这两个连词后面的从句的结构与前面的句子大部分情况下结构是相同的，相同部分可以省略。 He picked more apples than she did. 完整的表达为: He picked more apples than she picked apples. 后而的picked apples和前面相同，用did 替代。 He walked as slowly as she did.完整表达为: He walked as slowly as she walked slowly. she后面walked slowly与前面相同，用did替代。

3.谓语的替代 在as和than 引导的比较状语从句中，由于句式同前面 主句相同，为避免重复，常把主句中出现而从句中又出现的动词用do的适当形式来代替。 John speaks German as fluently as Mary does. 4.前后的比较对象应一致 不管后面连词是than 还是as,前后的比较对象应一致。The weather of Beijing is colder than Guangzhou. x than前面比较对象是“天气”，than 后面比较对象是“广州”，不能相比较。应改为: The weather of Bejing is colder than that of Guangzhou. 再如: His handwriting is as good as me. 应改为: His handwriting is as good as mine. 5.可以修饰比较级的词 常用来修饰比较级的词或短语有: Much,even,far,a little,a lot,a bit,by far,rather,any,still,a great deal等。 by far的用法: 用于强调，意为“...得多”“最最...”“显然”等，可修饰形容词或副词的比较级和最高级，通常置于其后，但是若比较级或最高级前有冠词，则可置于其前或其后。

The way常见用法

The way 的用法 Ⅰ常见用法： 1)the way+ that 2)the way + in which（最为正式的用法） 3)the way + 省略（最为自然的用法） 举例：I like the way in which he talks. I like the way that he talks. I like the way he talks. Ⅱ习惯用法： 在当代美国英语中，the way用作为副词的对格，“the way+ 从句”实际上相当于一个状语从句来修饰整个句子。 1)The way =as I am talking to you just the way I’d talk to my own child. He did not do it the way his friends did. Most fruits are naturally sweet and we can eat them just the way they are—all we have to do is to clean and peel them. 2）The way= according to the way/ judging from the way The way you answer the question, you are an excellent student. The way most people look at you, you’d think trash man is a monster. 3）The way =how/ how much No one can imagine the way he missed her. 4）The way =because

人教版(新目标)初中英语形容词与副词的比较级与最高级

人教版（新目标）初中英语形容词与副词的比较级与最高级 （一）规则变化： 1．绝大多数的单音节和少数双音节词，加词尾-er ，-est tall—taller—tallest 2．以不发音的e结尾的单音节词和少数以-le结尾的双音节词只加-r，-st nice—nicer—nicest , able—abler—ablest 3．以一个辅音字母结尾的重读闭音节词或少数双音节词，双写结尾的辅音字母，再加-er，-est big—bigger—biggest 4．以辅音字母加y结尾的双音节词，改y为i再加-er，-est easy—easier—easiest 5．少数以-er，-ow结尾的双音节词末尾加-er，-est clever—cleverer—cleverest, narrow—narrower—narrowest 6．其他双音节词和多音节词，在前面加more，most来构成比较级和最高级 easily—more easily—most easily （二）不规则变化 常见的有： good / well—better—best ; bad (ly)/ ill—worse—worst ; old—older/elder—oldest/eldest many / much—more—most ; little—less—least ; far—farther/further—farthest/furthest

用法： 1．原级比较：as + adj./adv. +as（否定为not so/as + adj./adv. +as）当as… as中间有名字时，采用as + adj. + a + n.或as + many / much + n. This is as good an example as the other is . I can carry as much paper as you can. 表示倍数的词或其他程度副词做修饰语时放在as的前面 This room is twice as big as that one. 倍数+as+adj.+as = 倍数+the +n.+of Your room is twice as larger as mine. = Your room is twice the size of mine. 2．比较级+ than 比较级前可加程度状语much, still, even, far, a lot, a little, three years. five times,20%等 He is three years older than I (am). 表示“（两个中）较……的那个”时，比较级前常加the（后面有名字时前面才能加冠词） He is the taller of the two brothers. / He is taller than his two brothers. Which is larger, Canada or Australia? / Which is the larger country, Canada or Australia? 可用比较级形式表示最高级概念，关键是要用或或否定词等把一事物（或人）与其他同类事物（或人）相分离 He is taller than any other boy / anybody else.

英语中的比较级和最高级

大多数形容词有三种形式,原级,比较级和最高级, 以表示形容词说明的性质在程度上的不同。 形容词的原级: 形容词的原级形式就是词典中出现的形容词的原形。例如: poor tall great glad bad 形容词的比较级和最高级: 形容词的比较级和最高级形式是在形容词的原级形式的基础上变化的。分为规则变化和不规则变化。 规则变化如下: 1) 单音节形容词的比较级和最高级形式是在词尾加 -er 和 -est 构成。 great (原级) (比较级) (最高级) 2) 以 -e 结尾的单音节形容词的比较级和最高级是在词尾加 -r 和 -st 构成。wide (原级) (比较级) (最高级) 3)少数以-y, -er, -ow, -ble结尾的双音节形容词的比较级和最高级是在词尾加 -er 和 -est 构成。 clever(原级) (比较级) (最高级) 4) 以 -y 结尾,但 -y 前是辅音字母的形容词的比较级和最高级是把 -y 去掉,加上 -ier 和-est 构成. happy (原形) (比较级) (最高级) 5) 以一个辅音字母结尾其前面的元音字母发短元音的形容词的比较级和最高级是双写该辅音字母然后再加 -er和-est。 big (原级) (比较级) (最高级) 6) 双音节和多音节形容词的比较级和最高级需用more 和 most 加在形容词前面来构成。 beautiful (原级) (比较级) (比较级) difficult (原级) (最高级) (最高级) 常用的不规则变化的形容词的比较级和最高级: 原级------比较级------最高级 good------better------best many------more------most much------more------most bad------worse------worst far------farther, further------farthest, furthest 形容词前如加 less 和 least 则表示"较不"和"最不 形容词比较级的用法: 形容词的比较级用于两个人或事物的比较,其结构形式如下: 主语+谓语(系动词)+ 形容词比较级+than+ 对比成分。也就是, 含有形容词比较级的主句+than+从句。注意从句常常省去意义上和主句相同的部分, 而只剩下对比的成分。

The way的用法及其含义(二)

The way的用法及其含义（二） 二、the way在句中的语法作用 the way在句中可以作主语、宾语或表语： 1.作主语 The way you are doing it is completely crazy.你这个干法简直发疯。 The way she puts on that accent really irritates me. 她故意操那种口音的样子实在令我恼火。The way she behaved towards him was utterly ruthless. 她对待他真是无情至极。 Words are important, but the way a person stands, folds his or her arms or moves his or her hands can also give us information about his or her feelings. 言语固然重要,但人的站姿,抱臂的方式和手势也回告诉我们他(她)的情感。 2.作宾语 I hate the way she stared at me.我讨厌她盯我看的样子。 We like the way that her hair hangs down.我们喜欢她的头发笔直地垂下来。 You could tell she was foreign by the way she was dressed. 从她的穿著就可以看出她是外国人。 She could not hide her amusement at the way he was dancing. 她见他跳舞的姿势，忍俊不禁。 3.作表语 This is the way the accident happened.这就是事故如何发生的。 Believe it or not, that's the way it is. 信不信由你, 反正事情就是这样。 That's the way I look at it, too. 我也是这么想。 That was the way minority nationalities were treated in old China. 那就是少数民族在旧中

英语比较级和最高级的用法归纳

英语比较级和最高级的用法归纳 在学习英语过程中，会遇到很多的语法问题，比如比较级和最高级的用法，对于 这些语法你能够掌握吗？下面是小编整理的英语比较级和最高级的用法，欢迎阅读！ 英语比较级和最高级的用法 一、形容词、副词的比较级和最高级的构成规则 1.一般单音节词和少数以-er，-ow结尾的双音节词，比较级在后面加-er，最高级 在后面加-est; (1)单音节词 如：small→smaller→smallest short→shorter→shortest tall→taller→tallest great→greater→greatest (2)双音节词 如：clever→cleverer→cleverest narrow→narrower→narrowest 2.以不发音e结尾的单音节词，比较在原级后加-r，最高级在原级后加-st; 如：large→larger→largest nice→nicer→nicest able→abler→ablest 3.在重读闭音节(即：辅音+元音+辅音)中，先双写末尾的辅音字母，比较级加-er，最高级加-est; 如：big→bigger→biggest hot→hotter→hottest fat→fatter→fattest 4.以“辅音字母+y”结尾的双音节词，把y改为i，比较级加-er，最高级加-est; 如：easy→easier→easiest heavy→heavier→heaviest busy→busier→busiest happy→happier→happiest 5.其他双音节词和多音节词，比较级在前面加more，最高级在前面加most; 如：bea utiful→more beautiful→most beautiful different→more different→most different easily→more easily→most easily 注意：(1)形容词最高级前通常必须用定冠词 the，副词最高级前可不用。 例句： The Sahara is the biggest desert in the world. (2) 形容词most前面没有the，不表示最高级的含义，只表示"非常"。 It is a most important problem. =It is a very important problem.

(完整版)the的用法

定冠词the的用法： 定冠词the与指示代词this ,that同源,有“那(这)个”的意思,但较弱,可以和一个名词连用,来表示某个或某些特定的人或东西. (1)特指双方都明白的人或物 Take the medicine.把药吃了. (2)上文提到过的人或事 He bought a house.他买了幢房子. I've been to the house.我去过那幢房子. (3)指世界上独一无二的事物 the sun ,the sky ,the moon, the earth (4)单数名词连用表示一类事物 the dollar 美元 the fox 狐狸 或与形容词或分词连用,表示一类人 the rich 富人 the living 生者 (5)用在序数词和形容词最高级,及形容词等前面 Where do you live?你住在哪? I live on the second floor.我住在二楼. That's the very thing I've been looking for.那正是我要找的东西. (6)与复数名词连用,指整个群体 They are the teachers of this school.(指全体教师) They are teachers of this school.(指部分教师) (7)表示所有,相当于物主代词,用在表示身体部位的名词前 She caught me by the arm.她抓住了我的手臂. (8)用在某些有普通名词构成的国家名称,机关团体,阶级等专有名词前 the People's Republic of China 中华人民共和国 the United States 美国 (9)用在表示乐器的名词前 She plays the piano.她会弹钢琴. (10)用在姓氏的复数名词之前,表示一家人 the Greens 格林一家人(或格林夫妇) (11)用在惯用语中 in the day, in the morning... the day before yesterday, the next morning... in the sky... in the dark... in the end... on the whole, by the way...

英语比较级和最高级的用法

More than的用法 A. “More than+名词”表示“不仅仅是” 1)Modern science is more than a large amount of information. 2)Jason is more than a lecturer; he is a writer, too. 3) We need more than material wealth to build our country.建设我们国家，不仅仅需要物质财富. B. “More than+数词”含“以上”或“不止”之意，如： 4)I have known David for more than 20 years. 5)Let's carry out the test with more than the sample copy. 6) More than one person has made this suggestion. 不止一人提过这个建议. C. “More than+形容词”等于“很”或“非常”的意思，如： 7)In doing scientific experiments, one must be more than careful with the instruments. 8)I assure you I am more than glad to help you. D. more than + (that)从句，其基本意义是“超过（=over）”，但可译成“简直不”“远非”.难以，完全不能（其后通常连用情态动词can） 9) That is more than I can understand . 那非我所能懂的. 10) That is more than I can tell. 那事我实在不明白。 11) The heat there was more than he could stand. 那儿的炎热程度是他所不能忍受的 此外，“more than”也在一些惯用语中出现，如： more...than 的用法 1. 比……多，比……更 He has more books than me. 他的书比我多。 He is more careful than the others. 他比其他人更仔细。 2. 与其……不如 He is more lucky than clever. 与其说他聪明，不如说他幸运。 He is more （a）scholar than （a）teacher. 与其说他是位教师，不如说他是位学者。 注：该句型主要用于同一个人或物在两个不同性质或特征等方面的比较，其中的比较级必须用加more 的形式，不能用加词尾-er 的形式。 No more than/not more than 1. no more than 的意思是“仅仅”“只有”“最多不超过”，强调少。如： --This test takes no more than thirty minutes. 这个测验只要30分钟。 --The pub was no more than half full. 该酒吧的上座率最多不超过五成。-For thirty years，he had done no more than he （had）needed to. 30年来，他只干了他需要干的工作。 2. not more than 为more than （多于）的否定式，其意为“不多于”“不超过”。如：Not more than 10 guests came to her birthday party. 来参加她的生日宴会的客人不超过十人。 比较： She has no more than three hats. 她只有3顶帽子。（太少了） She has not more than three hats. 她至多有3顶帽子。（也许不到3顶帽子） I have no more than five yuan in my pocket. 我口袋里的钱最多不过5元。（言其少） I have not more than five yuan in my pocket. 我口袋里的钱不多于5元。（也许不到5元） more than, less than 的用法 1. （指数量）不到，不足 It’s less than half an hour’s drive from here. 开车到那里不到半个钟头。 In less than an hour he finished the work. 没要上一个小时，他就完成了工作。 2. 比……（小）少 She eats less than she should. 她吃得比她应该吃的少。 Half the group felt they spent less than average. 半数人觉得他们的花费低于平均水平。 more…than,/no more than/not more than (1)Mr．Li is ________ a professor; he is also a famous scientist． (2)As I had ________ five dollars with me, I couldn’t afford the new jacket then． (3)He had to work at the age of ________ twelve． (4)There were ________ ten chairs in the room．However, the number of the children is twelve． (5)If you tel l your father what you’ve done, he’ll be ________ angry． (6)－What did you think of this novel? －I was disappointed to find it ________ interesting ________ that one． 倍数表达法 1. “倍数+形容词（或副词）的比较级+than+从句”表示“A比B大（长、高、宽等）多少倍” This rope is twice longer than that one.这根绳是那根绳的三倍（比那根绳长两倍）。The car runs twice faster than that truck.这辆小车的速度比那辆卡车快两倍（是那辆卡车的三倍）。 2. “倍数+as+形容词或副词的原级+as+从句”表示“A正好是B的多少倍”。

“the way+从句”结构的意义及用法

“tｈｅwａｙ+从句”结构的意义及用法 首先让我们来看下面这个句子: Ｒead the foｌloｗｉnｇpassagｅａnd talkａbout ｉt wi ｔh your classmaｔes．Try tｏｔeｌl whaｔyｏu thiｎk ｏf Tom aｎd ｏｆｔhe ｗay the chiｌｄrenｔrｅated ｈim. 在这个句子中，ｔhe waｙ是先行词,后面是省略了关系副词that或in whｉch的定语从句。 下面我们将叙述“the ｗaｙ+从句”结构的用法。 1.tｈe wａy之后，引导定语从句的关系词是tｈat而不是hoｗ,因此，<<现代英语惯用法词典＞＞中所给出的下面两个句子是错误的：Ｔhｉs is ｔｈeｗayｈowｉtｈａppened. This is the way how he ａlwａｙs treats me. 2．在正式语体中,thaｔ可被in which所代替;在非正式语体中，ｔhat则往往省略。由此我们得到theｗay后接定语从句时的三种模式：1) tｈe ｗaｙ＋ｔhａt-从句２）the way +ｉn whiｃh－从句3) the ｗay +从句 例如：Ｔｈe way(in whiｃh ，thａt) ｔhｅｓｅｃomｒade ｓloｏｋａｔｐrobｌems is wrong．这些同志看问题的方法

不对。 Ｔｈｅｗａy(that ,ｉn ｗhiｃh)yoｕ’ｒe doinｇit is comple ｔeｌy crａzy.你这么个干法,简直发疯。 Wｅａdmiｒｅd him for thｅｗay ｉｎｗhｉch he fａｃeｓdiｆficultieｓ． Waｌlａｃe ａｎd Ｄarwiｎｇreed ｏn the way ｉｎwhi ｃh ｄｉfｆｅrｅnt forms ｏf life had ｂegｕn.华莱士和达尔文对不同类型的生物是如何起源的持相同的观点。 Thｉs is ｔｈe ｗaｙ（tｈａｔ) hｅdｉd it. I lｉkeｄｔhe waｙ(ｔhat) ｓｈeｏｒganized ｔhe ｍeetｉng． 3.theｗay(tｈat)有时可以与hｏw(作“如何”解）通用。例如： That’s tｈe ｗaｙ(tｈaｔ) shｅspoke. = Tｈat’s how shｅspoke.

初中英语比较级和最高级讲解与练习

初中英语比较级和最高级讲解与练习 形容词比较级和最高级 一．绝大多数形容词有三种形式,原级,比较级和最高级, 以表示形容词说明的性质在程度上的不同。 1. 形容词的原级: 形容词的原级形式就是词典中出现的形容词的原形。例如: poor tall great glad bad 2. 形容词的比较级和最高级: 形容词的比较级和最高级形式是在形容词的原级形式的基 础上变化的。分为规则变化和不规则变化。 二．形容词比较级和最高级规则变化如下: 1) 单音节形容词的比较级和最高级形式是在词尾加-er 和-est 构成。 great (原级) greater(比较级) greatest(最高级) 2) 以-e 结尾的单音节形容词的比较级和最高级是在词尾加-r 和-st 构成。 wide (原级) wider (比较级) widest (最高级) 3) 少数以-y, -er, -ow, -ble结尾的双音节形容词的比较级和最高级是在词尾加 -er 和-est构成。 clever(原级) cleverer(比较级) cleverest(最高级)， slow(原级) slower(比较级) slowest (最高级) 4) 以-y 结尾,但-y 前是辅音字母的形容词的比较级和最高级是把-y 去掉,加上-ier 和-est 构成. happy (原形) happier (比较级) happiest (最高级) 5) 以一个辅音字母结尾其前面的元音字母发短元音的形容词的比较级和最高级是双写该 辅音字母然后再加-er和-est。 原形比较级最高级原形比较级最高级 big bigger biggest hot hotter hottest red redder reddest thin thinner thinnest 6) 双音节和多音节形容词的比较级和最高级需用more 和most 加在形容词前面来构 成。 原形比较级最高级 careful careful more careful most careful difficult more difficult most difficult delicious more delicious most delicious 7)常用的不规则变化的形容词的比较级和最高级: 原级比较级最高级 good better best 好的 well better best 身体好的 bad worse worst 坏的 ill worse worst 病的 many more most 许多 much more most 许多 few less least 少数几个 little less least 少数一点儿 （little littler littlest 小的） far further furthest 远（指更进一步，深度。亦可指更远） far farther farthest 远（指更远，路程）

way 用法

表示“方式”、“方法”，注意以下用法： 1.表示用某种方法或按某种方式，通常用介词in(此介词有时可省略)。如： Do it (in) your own way. 按你自己的方法做吧。 Please do not talk (in) that way. 请不要那样说。 2.表示做某事的方式或方法，其后可接不定式或of doing sth。 如： It’s the best way of studying [to study] English. 这是学习英语的最好方法。 There are different ways to do [of doing] it. 做这事有不同的办法。 3.其后通常可直接跟一个定语从句(不用任何引导词)，也可跟由that 或in which 引导的定语从句，但是其后的从句不能由how 来引导。如： 我不喜欢他说话的态度。 正：I don’t like the way he spoke. 正：I don’t like the way that he spoke. 正：I don’t like the way in which he spoke. 误：I don’t like the way how he spoke. 4.注意以下各句the way 的用法： That’s the way (=how) he spoke. 那就是他说话的方式。 Nobody else loves you the way(=as) I do. 没有人像我这样爱你。 The way (=According as) you are studying now, you won’tmake much progress. 根据你现在学习情况来看，你不会有多大的进步。 2007年陕西省高考英语中有这样一道单项填空题： ——I think he is taking an active part insocial work. ——I agree with you_____. A、in a way B、on the way C、by the way D、in the way 此题答案选A。要想弄清为什么选A，而不选其他几项，则要弄清选项中含way的四个短语的不同意义和用法，下面我们就对此作一归纳和小结。 一、in a way的用法 表示：在一定程度上，从某方面说。如： In a way he was right.在某种程度上他是对的。注：in a way也可说成in one way。 二、on the way的用法 1、表示：即将来(去)，就要来(去)。如： Spring is on the way.春天快到了。 I'd better be on my way soon.我最好还是快点儿走。 Radio forecasts said a sixth-grade wind was on the way.无线电预报说将有六级大风。 2、表示：在路上，在行进中。如： He stopped for breakfast on the way.他中途停下吃早点。 We had some good laughs on the way.我们在路上好好笑了一阵子。 3、表示：(婴儿)尚未出生。如： She has two children with another one on the way.她有两个孩子，现在还怀着一个。 She's got five children，and another one is on the way.她已经有5个孩子了，另一个又快生了。 三、by the way的用法

英语比较级和最高级

形容词比较级和最高级的形式 一、形容词比较级和最高级的构成 形容词的比较级和最高级变化形式规则如下 构成法原级比较级最高级 ①一般单音节词末尾加 er 和 est strong stronger strongest ②单音节词如果以 e结尾，只加 r 和 st strange stranger strangest ③闭音节单音节词如末尾只有一个辅音字母， 须先双写这个辅音字母，再加 er和 est sad big hot sadder bigger hotter saddest biggest hottest ④少数以 y, er(或 ure), ow, ble结尾的双音节词， 末尾加 er和 est(以 y结尾的词，如 y前是辅音字母， 把y变成i，再加 er和 est，以 e结尾的词仍 只加 r和 st) angry Clever Narrow Noble angrier Cleverer narrower nobler angriest cleverest narrowest noblest ⑤其他双音节和多音节词都在前面加单词more和most different more different most different 1) The most high 〔A〕mountain in 〔B〕the world is Mount Everest，which is situated 〔C〕in Nepal and is twenty nine thousand one hundred and fourty one feet high 〔D〕 . 2) This house is spaciouser 〔A〕than that 〔B〕white 〔C〕one I bought in Rapid City，South Dakota 〔D〕last year. 3) Research in the social 〔A〕sciences often proves difficulter 〔B〕than similar 〔C〕work in the physical 〔D〕sciences. 二、形容词比较级或最高级的特殊形式：

高中英语的比较级和最高级用法总结

比较级和最高级 1.在形容词词尾加上―er‖ ―est‖ 构成比较级、最高级： bright（明亮的）—brighter—brightest broad（广阔的）—broader—broadest cheap（便宜的）—cheaper—cheapest clean（干净的）—cleaner—cleanest clever（聪明的）—cleverer—cleverest cold（寒冷的）—colder—coldest cool（凉的）—cooler—coolest dark（黑暗的）—darker—darkest dear（贵的）—dearer—dearest deep（深的）—deeper—deepest fast（迅速的）—faster—fastest few（少的）—fewer—fewest great（伟大的）—greater—greatest hard（困难的,硬的）—harder—hardest high（高的）—higher—highest kind（善良的）—kinder—kindest light（轻的）—lighter—lightest long（长的）—longer—longest loud（响亮的）—louder—loudest low（低的）—lower—lowest near（近的）—nearer—nearest new（新的）—newer—newest poor（穷的）—poorer—poorest quick（快的）—quicker—quickest quiet（安静的）—quieter—quietest rich（富裕的）—richer—richest short（短的）—shorter—shortest slow（慢的）—slower—slowest small（小的）—smaller—smallest smart（聪明的）—smarter—smartest soft（柔软的）—softer—softest strong（强壮的）—stronger—strongest sweet（甜的）—sweeter—sweetest tall（高的）-taller-tallest thick（厚的）—thicker—thickest warm（温暖的）—warmer—warmest weak（弱的）—weaker—weakest young（年轻的）—younger—youngest 2.双写最后一个字母,再加上―er‖ ―est‖构成比较级、最高级： big（大的）—bigger—biggest fat（胖的）—fatter—fattest hot（热的）—hotter—hottest red（红的）—redder—reddest sad（伤心的）—sadder—saddest thin（瘦的）—thinner—thinnest wet（湿的）—wetter—wettest mad（疯的）—madder—maddest 3.以不发音的字母e结尾的形容词,加上―r‖ ―st‖ 构成比较级、最高级：able（能干的）—abler—ablest brave（勇敢的）—braver—bravest close（接近的）—closer—closest fine（好的,完美的）—finer—finest large（巨大的）—larger—largest late（迟的）—later—latest nice（好的）—nicer—nicest ripe（成熟的）—riper—ripest

The way的用法及其含义(一)

The way的用法及其含义（一） 有这样一个句子：In 1770 the room was completed the way she wanted. 1770年，这间琥珀屋按照她的要求完成了。 the way在句中的语法作用是什么？其意义如何？在阅读时，学生经常会碰到一些含有the way 的句子，如：No one knows the way he invented the machine. He did not do the experiment the way his teacher told him.等等。他们对the way 的用法和含义比较模糊。在这几个句子中，the way之后的部分都是定语从句。第一句的意思是，“没人知道他是怎样发明这台机器的。”the way的意思相当于how；第二句的意思是，“他没有按照老师说的那样做实验。”the way 的意思相当于as。在In 1770 the room was completed the way she wanted.这句话中，the way也是as的含义。随着现代英语的发展，the way的用法已越来越普遍了。下面，我们从the way的语法作用和意义等方面做一考查和分析： 一、the way作先行词，后接定语从句 以下3种表达都是正确的。例如：“我喜欢她笑的样子。” 1. the way+ in which +从句 I like the way in which she smiles. 2. the way+ that +从句 I like the way that she smiles. 3. the way + 从句(省略了in which或that) I like the way she smiles. 又如：“火灾如何发生的，有好几种说法。” 1. There were several theories about the way in which the fire started. 2. There were several theories about the way that the fire started.

(完整版)初中英语比较级和最高级的用法

英语语法---比较级和最高级的用法 在英语中通常用下列方式表示的词:在形容词或副词前加more(如 more natural,more clearly )或加后缀 -er(newer,sooner )。典型的是指形容词或副词所表示的质、量或关系的增加。英语句子中，将比较两个主体的方法叫做“比较句型”。其中，像“A比B更……”的表达方式称为比较级；而“A最……”的表达方式则称为最高级。组成句子的方式是将形容词或副词变化成比较级或最高级的形态。 一、形容词、副词的比较级和最高级的构成规则 1．一般单音节词和少数以-er，-ow结尾的双音节词，比较级在后面加-er，最高级在后面加-est； （1）单音节词 如：small→smaller→smallest short→shorter→shortest tall→taller→tallest great→greater→greatest （2）双音节词 如：clever→cleverer→cleverest narrow→narrower→narrowest 2．以不发音e结尾的单音节词，比较在原级后加-r，最高级在原级后加-st； 如：large→larger→largest nice→nicer→nicest able→abler→ablest 3．在重读闭音节（即：辅音＋元音＋辅音）中，先双写末尾的辅音字母，比较级加-er，最高级加-est； 如：big→bigger→biggest hot→hotter→hottest fat→fatter→fattest 4．以“辅音字母＋y”结尾的双音节词，把y改为i，比较级加-er，最高级加-est； 如：easy→easier→easiest heavy→heavier→heaviest busy→busier→busiest happy→happier→happiest 5．其他双音节词和多音节词，比较级在前面加more，最高级在前面加most； 如：beautiful→more beautiful→most beautiful different→more different→most different easily→more easily→most easily