This article was downloaded by: [Laurentian University] On: 28 April 2013, At: 13:33 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK International Journal of Food Properties Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ljfp20 Total Antioxidant Activity and Phenols and Flavonoids Content of Several Plant Extracts Claudia-Valentina Popa a , Liliana Lungu b , Manuela Savoiu b , Corina Bradu a , Vasile Dinoiu b & Andrei Florin Danet a a Faculty of Chemistry, University of Bucharest, Bucharest, Romania b Institute of Organic Chemistry C.D. Nenitzescu, Bucharest, Romania Accepted author version posted online: 05 Jul 2011. To cite this article: Claudia-Valentina Popa , Liliana Lungu , Manuela Savoiu , Corina Bradu , Vasile Dinoiu & Andrei Florin Danet (2012): Total Antioxidant Activity and Phenols and Flavonoids Content of Several Plant Extracts, International Journal of Food Properties, 15:3, 691-701 To link to this article: http://dx.doi.org/10.1080/10942912.2010.498545 PLEASE SCROLL DOWN FOR ARTICLE Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material.
Transcript
This article was downloaded by: [Laurentian University]On: 28 April 2013, At: 13:33Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registeredoffice: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK
International Journal of Food PropertiesPublication details, including instructions for authors andsubscription information:http://www.tandfonline.com/loi/ljfp20
Total Antioxidant Activity and Phenolsand Flavonoids Content of Several PlantExtractsClaudia-Valentina Popa a , Liliana Lungu b , Manuela Savoiu b , CorinaBradu a , Vasile Dinoiu b & Andrei Florin Danet aa Faculty of Chemistry, University of Bucharest, Bucharest, Romaniab Institute of Organic Chemistry C.D. Nenitzescu, Bucharest,RomaniaAccepted author version posted online: 05 Jul 2011.
To cite this article: Claudia-Valentina Popa , Liliana Lungu , Manuela Savoiu , Corina Bradu , VasileDinoiu & Andrei Florin Danet (2012): Total Antioxidant Activity and Phenols and Flavonoids Content ofSeveral Plant Extracts, International Journal of Food Properties, 15:3, 691-701
To link to this article: http://dx.doi.org/10.1080/10942912.2010.498545
PLEASE SCROLL DOWN FOR ARTICLE
Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions
This article may be used for research, teaching, and private study purposes. Anysubstantial or systematic reproduction, redistribution, reselling, loan, sub-licensing,systematic supply, or distribution in any form to anyone is expressly forbidden.
The publisher does not give any warranty express or implied or make any representationthat the contents will be complete or accurate or up to date. The accuracy of anyinstructions, formulae, and drug doses should be independently verified with primarysources. The publisher shall not be liable for any loss, actions, claims, proceedings,demand, or costs or damages whatsoever or howsoever caused arising directly orindirectly in connection with or arising out of the use of this material.
TOTAL ANTIOXIDANT ACTIVITY AND PHENOLS ANDFLAVONOIDS CONTENT OF SEVERAL PLANT EXTRACTS
Claudia-Valentina Popa1, Liliana Lungu2, Manuela Savoiu2,Corina Bradu1, Vasile Dinoiu2, and Andrei Florin Danet1
1Faculty of Chemistry, University of Bucharest, Bucharest, Romania2Institute of Organic Chemistry C.D. Nenitzescu, Bucharest, Romania
Alcoholic extracts of six culinary and medicinal plants have been analyzed for theirantioxidative properties. Extracts were obtained by continuous (Soxhlet) and ultrasoundsextraction. A new flow injection analysis method with chemiluminescence detection basedon a luminol/Co(II)/EDTA/H2O2 system was set up for the total antioxidant capacity deter-mination of the studied extracts. For comparison, total phenols and flavonoids contents ofplant extracts were determined by spectrophotometric methods. A good correlation betweentotal phenols and total antioxidant capacity was found for some determinations.
Keywords: Total antioxidant capacity, Polyphenols, Flavonoids, Chemiluminescenceanalysis, Culinary herbs.
INTRODUCTION
Phenols are substantial components of plant foods[1] and, therefore, important con-stituents of a human diet.[2] The antioxidant activity of plants (such as rosemary, sage,green tea, etc.) might be in a great part attributable to their polyphenolic contents.[3] Somewell known examples, such as hydroxycinnamic acids (especially represented by caffeicacid and chlorogenic acid) and flavonoids (flavones and anthocyanins) can be mentionedfor their good antioxidant properties. Flavonoids are considered efficient ingredients offruits and vegetables, food grains, herbal remedies, dietary supplements, etc.[4,5] Thesecompounds exhibit antioxidant capacity by different mechanisms including: scavengingreactive oxygen species (ROS), such as superoxide anion radical (O2
.−), hydroxyl rad-ical (HO.), peroxide radicals (ROO.) or hydroperoxyl (HOO.), alkoxyl (R-O.), hydrogenperoxide (H2O2), singlet oxygen (1O2), etc.;[5,6] chelating of transition metal ions;[7] medi-ation or inhibition of hydrolytic and oxidative enzymes action;[4] interaction with otherantioxidants,[7] etc. Anthocyanins, well known for their strong antioxidant activity,[8] arean important class of flavonoids.
Studying the mechanism of polyphenols antioxidant activity, it can be noticed thatthese compounds showed low redox potentials, which allow them to act as reducingagents.[9,10] In addition, these compounds have a metal-chelating potential.[9] A singlehydroxyl substituent generates a little or no antioxidant activity, but the increased number
Received 4 March; accepted 30 May 2010.Address correspondence to Andrei Florin Danet, Faculty of Chemistry, University of Bucharest, Panduri
of hydroxyl groups produces an amplified antioxidant activity of phenolic compounds.[2]
Dietary phenolic phytochemicals show antioxidant activity to be even stronger than thatof vitamin C,[11] protecting the organisms from the effects of free radicals, and ROS inbiological systems.[12–16] Polyphenols have many beneficial effects on health by decreas-ing the risk of diseases, such as heart diseases (by inhibiting the oxidation of low-densityproteins),[17] cancer,[1,12,13,16–19] cerebrovascular,[11] neurodegenerative (e.g., Alzheimer’sdisease),[20] rheumatoid arthritis,[12,21] etc.
The aim of our research was to investigate total antioxidant capacity (TAC) andpolyphenols content of alcoholic extracts from leaves or herba of some very used culinaryand medicinal herbs, such as Anethum graveolens L. (Apiaceae, dill), Camellia sinen-sis L. Kuntze (Theaceae, green tea), Levisticum officinale L. Koch. (Apiaceae, lovage),Petroselinum sativum Hoffm. (Apiaceae, parsley), Rosmarinus officinalis L. (Lamiaceae,rosemary), and Salvia officinalis L. (Lamiaceae, sage). The literature data[7,22,23] illus-trate that these plants contain polyphenolic compounds with antioxidant capacity (e.g.,flavonoids and other polyphenols), polyphenolic acids (caffeic, ferulic, chlorogenic acids),etc. A new procedure was set up for TAC determination of obtained extracts by flowinjection analysis (FIA)[24,25] with chemiluminometric detection (FIA-CL) based on aluminol/Co(II)/EDTA/H2O2 system.[12,26,27] The mentioned CL system was scarcelystudied for antioxidant determination and has a good sensitivity and reproducibility ofmeasurements.[12,28] The coupling of FIA with luminol/Co(II)/EDTA/H2O2 chemilu-minometric system for antioxidant determination present the advantage of high samplethroughput and a low consumption of reagents. The total phenols (TP) and flavonoids con-tent of plant extracts was spectrophotometrically estimated by using caffeic acid, gallicacid, ferulic acid, and, respectively, quercetin as standards. The relationship betweenTAC and TP was studied. A comparison between results in this study and literaturewas made.
MATERIALS AND METHODS
Chemicals
Chemicals used in this study are as follows: boric acid, cobalt(II) chloride hex-ahydrate (both from Reactivul, Bucharest, Romania); hydrogen peroxide 30% w/v(Chimopar, Bucharest, Romania); EDTA (ethylenediaminetetraacetic acid disodium salt)(Loba Chemie); luminol (5-amino-2,3-dihydronaphtalazine-1,4-dione) (Fluka BioChemie,Slovakia); caffeic acid, ferulic acid, quercetin (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-chromen-4-one) dihydrate (all from Sigma); gallic acid monohydrate (Riedel-deHaën);Folin-Ciocalteu reagent, aluminum chloride hexahydrate, potassium acetate, sodium car-bonate (all from Merck); sodium hydroxide (Chemapol); methanol and acetone (ChemicalCompany, Iasi, Romania); and ethanol (S.C. P.A.M. Corporation S.R.L., Bucharest,Romania).
Reagents for FIA-CL Method
For the solution of Co(II)/EDTA/luminol prepared in 0.05 mol/L sodium boratebuffer, pH 9, the borate buffer was obtained from a boric acid solution adjusted to pHwith a 10% NaOH solution. In Co(II)/EDTA/luminol solution, the EDTA concentra-tion was 10−3 mol/L, molar ratio Co(II)/EDTA was 0.8, and luminol concentration was
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CONTENT OF SEVERAL PLANT EXTRACTS 693
2.3 × 10−4 mol/L. The reagents were dissolved in the buffer solution with pH 9 in thefollowing order: EDTA, cobalt(II) chloride, and luminol. For the solution of 6 × 10−4
mol/L H2O2 prepared in 2 × 10−4 mol/L EDTA solution, EDTA was used to complexthe traces of metallic ions, which decompose catalytically H2O2. Stock solutions of caffeicand gallic acids 10−3 mol/L were prepared in a mixture of acetone and 2 × 10−4 mol/Laqueous solution EDTA in a ratio of 70:30 (v/v). Working solutions of caffeic acid andgallic acid (2.5–300 µmol/L) were prepared from corresponding stock solutions dilutedwith the above-mentioned mixture and then submitted to ultrasonic treatment (∼1 min) toeliminate air bubbles, before FIA-CL analysis. All solutions were prepared, unless other-wise mentioned, in doubly distilled water for FIA-CL analysis and in distilled water forspectrophotometric methods.
Preparation of Plant Extracts
Sage, rosemary, and green tea (leaves) were purchased from “Plafar” (Romania).Dill, lovage, and parsley (herba) were bought from growers and dried at room tempera-ture. The dried vegetable material was powdered in a grinder and then extracted by: (i)Continuous extraction: Vegetable material was exhausted in ethanol 96% in a Soxhletapparatus; the ratio of plant material to solvent was 1:10 w/v. (ii) Ultrasonic extractionwas carried out by using an ultrasonic cleaning bath, vegetal material/ethanol 96% ratio1:10 (w/v), extraction time 60 min. After filtration and alcohol removal (using a rotaryevaporator), the extracts obtained were dried in an oven at 100◦C for 1 h.
Apparatus
The FI assembly for chemiluminescence (CL) determination of antioxidant activ-ity (presented in Fig. 1) is composed of a peristaltic pump with four channels (Gilson),a Rheodyne type model 5051 injection valve, a CL detector specially designed for FIAanalysis, and a computer with software for CL signal recording. The CL detector consistsof a photomultiplier tube (PMT, power supply 1000 V), an amplifier system, a displayscreen, and a flow cell. The flow cell utilized for the experiments was manufactured inour laboratory by spiraling a Teflon tube (i.d. = 0.8 mm) in the same plan. Eight spiralswere thus obtained. The cell was placed on a reflecting aluminum thin foil, in front ofthe PMT window. A single beam Cole Parmer 1100 RS spectrophotometer was used forspectrophotometric determination. An ultrasonic cleaning bath (Langford Sonomatic, fre-quency 33 kHz at 100 W working power) was used for ultrasonic extraction of vegetalmaterial.
Working Procedure for Total Antioxidant Capacity (TAC) Determination
by FIA-CL Method
The FIA-CL assembly presented in Fig. 1 was used. The total flow rate for all threefluxes was 0.45 mL/min (0.15 mL/min on each channel); the injection volume of sam-ples and standard solutions was 70 µL. Temperature was maintained at 24–28◦C. For thebeginning, it was pumped a 0.05 mol/L sodium borate buffer pH 9 solution (carrier) bychannel (a), the H2O2 solution by channel (b), and the Co(II)/EDTA/luminol solutionby channel (c), till a constant chemiluminescence signal, ICL, was recorded (minimum10 min). In the absence of an injected sample, the signal has the aspect of a plateau (Fig. 2).
Figure 2 Shape of FIA-CL signals. RLU: Relative chemiluminescence units; ICL: Intensity of backgroundchemiluminescence signal; I�CL: Decrease of chemiluminescence signal in the presence of an antioxidant.
By injecting in the carrier stream the solution of an antioxidant (standards/analyzed sam-ples) the chemiluminescence signal decreases (Fig. 2). The value of signal decreasing,I′
�CL, depends on the concentration and the activity of the antioxidant in the analyzedsample. The I�CL value measured for the blank sample (doubly distilled water) was sub-tracted from I�CL measured for analyzed samples and, thus, an I′
�CL value was obtained.Then, the percentage of decrease of CL signal for analyzed samples was calculated asfollows:
(I′�CL/ICL
) × 100. (1)
By representing (I′�CL/ICL × 100) vs. concentration of standards (µmol/L), the calibrationcurves of caffeic and gallic acids were obtained. The results for TAC of analyzedsamples were expressed in mg equivalent caffeic or gallic acid per 100 g dry weight(dw) plant.
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CONTENT OF SEVERAL PLANT EXTRACTS 695
Working Procedure for TP Determination
TP content was determined using the Folin-Ciocalteu method (FCM)[29] as follows:0.5 mL sample or standards (gallic acid, caffeic acid, ferulic acid) was mixed with 5 mLFolin-Ciocalteu (1:10 diluted with distilled water) and 4 mL 1 mol/L sodium carbon-ate solution. Concentration of standard solutions prepared in methanol:water = 50% (v/v)used for calibration curves were between 10 and 150 mg/L. Absorbance was measuredafter 15 min at room temperature against blank (methanol 50% v/v), in a 1-cm glass testtube, at 736 nm for caffeic acid, 746 nm for gallic acid, and 756 nm for ferulic acid.
Working Procedure for Flavonoids Determination
An aluminum chloride colorimetric method[3] was used for flavonoids determina-tion. Thus, 1 mL of sample or standard (quercetin 10–100 mg/L methanolic solutions) wasmixed with 3 mL of methanol, 0.2 mL 10% aluminum chloride solution, 0.2 mL 1 mol/Lpotassium acetate solution, and 5.6 mL of distilled water. After 30 min at room tempera-ture, the absorbance was measured at 430 nm in a 1-cm glass test tube against methanolas blank. The calibration curve was drawn. For all described methods, at least two deter-minations were performed for each sample and the results were reported as means of themeasurements.
RESULTS AND DISCUSSION
The FIA-CL method is based on the reaction of luminol with hydroxyl radicals pro-duced by the reaction of H2O2 with Co(II) ions released from the Co(II)/EDTA complex.Due to the very low concentration of Co(II) ions (owing to its complexation by EDTA) theconcentration of HO.radicals is very low, too. By pumping the carrier, H2O2 solution, andCo(II)/EDTA/luminol solution through the three channels of the FIA assembly (Fig. 1),the HO. react with luminol producing a CL radiation with a constant intensity that has theaspect of a plateau (Fig. 2). If an antioxidant (standard or sample) solution is injected intothe carrier stream during the constant emission of light (plateau), a decrease of the CL sig-nal, with the aspect of a reversed peak (Fig. 2), is registered. Its height is related with thetype, activity, and concentration of the antioxidant.[12,28]
Calibration Curves
For TAC determinations, the calibration graphs obtained by representing(I′�CL/ICL × 100) vs. concentration of antioxidants (µmol/L) are shown in Fig. 3a. Linearrange of each curve is presented in Fig. 3b. The equations and correlation coefficient forlinear ranges of curves presented in Fig. 3 are presented in Table 1. Calibration curvesused for total phenols and flavonoids determinations were drawn; equations, correlationcoefficients, and linear range are presented in Table 1.
Determination of TAC, TP and Flavonoids Contents in Vegetable
Extracts
Sample preparation for analysis. Plant extracts were obtained as described inthe “MATERIAL AND METHODS” section. For FIA-CL analysis, 0.01 g of each plant
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696 POPA ET AL.
100 60
40
20
00 20 40 60
a b
80
60
I’ΔC
L/I
CL ×
100
40
20
00 100 200
Gallic acid
Caffeic acid
Gallic acid
Caffeic acid
300
Concentration of antioxidants (μmol/L)
Figure 3 Calibration curves for caffeic and gallic acids determined by FIA-CL. (a) calibration curves;(b) linearity domains.
Table 1 Equations, correlation coefficients, and linear range for obtained calibration curves.
Antioxidant Analytical method Equation (r2/n) Linear range
Gallic acid FIA-CL Y = 0.679x + 15.4 0.9986/6 4–50 (µmol/L)Caffeic acid Y = 0.748x + 21.3 0.9785/5 4–35 (µmol/L)Gallic acid FCM y = 0.00638x + 0.0388 0.9998/5 50–150 (mg/L)Caffeic acid y = 0.00656x + 0.0265 0.9997/5 25–125 (mg/L)Ferulic acid y = 0.00513x + 0.0199 0.9983/7 10–125 (mg/L)Quercetin Colorimetric, with AlCl3 y = 0.00886x + 0.000617 0.9996/8 10–100 (mg/L)
�CL/ICL × 100; y: absorbance; x: concentration of standards (expressed in µmol/L for FIA-CL and mg/L forspectrophotometric determinations); (r2/n): correlation coefficient/number of measurement.
extract was dissolved in 7 mL of acetone, then 3 mL of 2 × 10−4 mol/L EDTA aque-ous solution was added, and solutions were submitted to ultrasound treatment (∼1 min.)before analysis. Samples for TP determinations were prepared as follows: 0.1 g from eachplant extract was dissolved in 25 mL of methanol:water = 50% (v/v) mixture and filtered.Subsequently, a 1 mL sample was diluted to 25 mL with methanol 50% (v/v). For deter-mination of flavonoids in vegetable extracts we proceed as follows: 0.1 g from each extractwas dissolved in 25 mL of methanol and the resulted solution filtered.
Results for the TAC determination in plant extracts. It can be seen fromTable 2 that TAC values of plant extracts varied between 28.6 and 7049 mg equivalentgallic acid/100 g dw and between 63.4 and 6061 mg/100 g dw in terms of caffeic acidequivalent. It can also be observed that the values of TAC determined for extracts obtainedby continuous extraction are higher than those obtained by ultrasounds extraction, withthe exception of A. graveolens. Generally, extracts of C. sinensis, R. officinalis, and S.officinalis have a TAC higher than P. sativum, A. graveolens, and L. officinale.
Results for TP and total flavonoids determination in plant extracts. Itcan be seen from Table 3 that TP content of plant extracts varies from 60.0 to 3455 mgequivalent gallic acid/100 g dw, from 21.0 to 2739 mg equivalent caffeic acid/100 g dw,and from 103 to 4581 mg equivalent ferulic acid/100 g dw. The results in this study
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CONTENT OF SEVERAL PLANT EXTRACTS 697
Table 2 Total antioxidant capacity of plant extracts.
Total antioxidant capacity∗
mg equivalent gallic acid/100 g dw∗∗ mg equivalent caffeic acid/100 g dw
∗Values are expressed as mean of measurements (n = 2).∗∗Plant dry weight.
matched with literature data regarding TP content for some plant extracts. For example,it was found for different types of C. sinensis: 30–196 mg equivalent gallic acid/g dw;[22]
91.7–184.2 mg equivalent gallic acid/g dw in leaf tea;[30] and 14.32–21.02 g equivalentgallic acid/100 g dw in three extracts from green tea leaf bags,[31] using the same analyticalmethod (FCM).
Some authors reported for R. officinalis: 406 mg caffeic acid/100 g dw,[32] 36.2 mgferulic acid/100 g dw;[32] for S. officinalis: 296 mg caffeic acid/100 g dw,[32] 13.5 mg ferulicacid/100 g dw;[32] for L. officinale: 390 mg caffeic acid/100 g dw, 76.2 mg ferulic acid/100 gdw, respectively.[32] TP content of extracts obtained with Soxhlet extractor varied as follows:caffeic acid equivalent < gallic acid equivalent < ferulic acid equivalent (Table 3). For bothtypes of extracts, the TP content expressed in terms of ferulic acid equivalent had the highestvalues, except the results for C. sinensis ultrasonically obtained extract.
Flavonoids content of analyzed plant extracts varied between 56.3 and 345 mgquercetin equivalent/100 g dw (Table 2). The literature data reported: 178 mgquercetin/100 g dw[32] for S. officinalis; 923 mg quercetin/100 g dw[32] or 170 mgquercetin/100 g dw[33] in L. officinale extract; and 48–110 mg quercetin/100 g dw forA. graveolens.[33] Our results agree with these literature data. The flavonoids content fromplant extracts obtained by continuous extraction showed higher values than those obtainedby ultrasonic treatment. The extracts of C. sinensis, R. officinalis, and S. officinalis presentthe highest content of polyphenols compounds and highest TAC. A. graveolens extractswere characterized by low values of TP and flavonoids contents and TAC.
Relationship between TAC and TP in the Analyzed Samples
It can be seen from Fig. 4 that correlation coefficients show a high association levelbetween TAC and TP for Soxhlet obtained extracts when expressed as gallic acid equiv-alents (r2 = 0.9821, graph 1) and for ultrasonically obtained extracts, when expressed ascaffeic acid equivalents (r2 = 0.9648, graph 4). No significant association was found for theother determination: r2 = 0.1567, graph 2 for ultrasonically obtained extracts in terms ofgallic acid and r2 = 0.1886, graph 3 for Soxhlet obtained extracts, in terms of caffeic acid.
The results in this study agreed with literature reports. For example, Chang et al.[17]
found that the correlation coefficient between antioxidant capacity analyzed by the ABTSmethod (mmol/L Trolox equivalent) and total polyphenols determined by FCM (µg
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Tabl
e3
Tota
lphe
nols
and
flavo
noid
sco
nten
tin
plan
text
ract
sob
tain
edby
cont
inuo
usan
dul
tras
ound
sex
trac
tion.
Tota
lphe
nols
cont
ent∗
Flav
onoi
dsco
nten
t∗
mg
equi
vale
ntga
llic
acid
/10
0g
dw∗∗
mg
equi
vale
ntca
ffei
cac
id/10
0g
dwm
geq
uiva
lent
feru
licac
id/10
0g
dwm
geq
uiva
lent
quer
cetin
/10
0g
dw
Sam
ple
Con
tinuo
usex
trac
tion
Ultr
asou
nds
extr
actio
nC
ontin
uous
extr
actio
nU
ltras
ound
sex
trac
tion
Con
tinuo
usex
trac
tion
Ultr
asou
nds
extr
actio
nC
ontin
uous
extr
actio
nU
ltras
ound
sex
trac
tion
Cam
elli
asi
nens
is34
5533
0632
127
3945
8117
9734
533
3R
osm
arin
usof
ficin
alis
1416
565
1222
776
1922
879
246
228
Salv
iaof
ficin
alis
612
670
342
569
725
829
246
159
Petr
osel
inum
sati
vum
335
60.0
218
88.5
333
147
103
56.3
Lev
isti
cum
offic
inal
e21
086
.513
589
.524
815
727
999
.5A
neth
umgr
aveo
lens
102
108
21.0
88.1
103
214
147
61.3
∗ Val
ues
are
expr
esse
das
mea
nof
mea
sure
men
ts(n
=2)
.∗∗
Plan
tdry
wei
ght.
698
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CONTENT OF SEVERAL PLANT EXTRACTS 699
7500
6000
4500
2
34
GAE
GAE
CAE
CAE
3000
TA
C1500
0
TP
0 2000 4000
1
Figure 4 Correlation graphs of total antioxidant capacity (TAC) vs. total phenol (TP) content of plant extractsobtained by continuous (graph 1, 2) and ultrasounds (graph 3, 4) extraction. GAE: mg equivalent gallic acid/100 gdw; CAE: mg equivalent caffeic acid/100 g dw.
catechin equivalent/mg dw) of six folk medicinal ferns’ ethanolic extracts was 0.981.By comparison, between antioxidant activity determined by ABTS, DPPH, and FRAPmethods (µmol Trolox/100 g dw) and TP contents determined using HPLC/UV-VIS(mg gallic acid equivalents/100 g dw), Wojdylo et al.[32] reported the correlation coeffi-cients (r2) for selected species from Labiatae 0.9263, 0.8352, and 0.9100; for Compositae,0.9620, 0.6709, and 0.9193, respectively.
CONCLUSIONS
Extracts from six culinary and medicinal herbs were obtained by continuous andultrasonic extraction. Total antioxidant capacity of the extracts was determined by anew FIA-CL method and total phenols and flavonoids content was determined by con-ventional spectrophotometric methods. The analytical performance of the new FIA-CLmethod and its application for determination of antioxidant activity of wines were reportedelsewhere.[28] The sensitivity of the new FIA-CL method for TAC determination wasabout three orders of magnitude bigger than that of the spectrophotometric ones in accor-dance with the literature.[27,34] The throughput was 10 samples/h and the consumption ofreagents was of a 3 mL/sample making it efficient for total antioxidant activity determina-tion of plant extracts. A good correlation between antioxidant activity and phenols’ contentof analyzed plant extracts was established. The obtained data were in good agreement withliterature data regarding similar plant extracts. For the future we intend to couple the stud-ied flow CL system with the outlet of a chromatographic column in order to detect on-linewith a high sensitivity the antioxidants separated from different samples and especiallyfrom plant extracts.
ACKNOWLEDGMENTS
Financial support from the Romanian projects ECOMAT 71-079/2007 and SENSALIM71-098/2007, CNMP (Centrul National de Management Programe), MECIT (Ministerul Educatiei,Cercetarii, Inovarii si Tineretului), Romania is gratefully acknowledged.
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