The amounts of flavonoid (myricetin , quercetin and kaempferol), antioxidant contents ( total phenolic and total flavonoid) and antioxidant activities (DPPH and FRAP) were analyzed in strawberry. Quantitative analysis of conjugated flavonoid contents were obtained after different hydrolysis concentration and reaction period . The highest yields of myricetin and quercetin were found with 1.0M HCl and a reaction period of 0.5 hr, however , for kaempferol was 1.0M HCl and a reaction period of 1hr , respectively. In the study, we also estimated the correlation coefficient of TPC, TFC, DPPH and FRAP. In addition , a positive correlation was observed ( r = 0.980, P < 0.05) between TPC and TFC, TPC and TFC are correlated to the DPPH activity (r = 0.913, P < 0.05 and r = 0.899 , P < 0.05 , respectively) , and to the FRAP activity ( r = 0.958, P < 0.05 and r = 0.936, P < 0.05, respectively), respectively. These results pointed out that strawberry generally possesses a high level of antioxidant activities, which could be linked to the levels of phenolic compounds in the fruit.
全 文 :草莓中黄酮类物质的测定以及与抗氧化活性
之间的相互关系
郑虎哲1 ,2 , Lee Hye-ryun1 , 崔春兰2 , Hwang In-wook1 ,
Kwon Sun-young1 , Chung Shin-kyo1
?
( 1 韩国国立庆北大学校农业生命科学学院食品工学部 , 大邱 702 - 701 , 韩国 ;
2 辽宁农业职业技术学院农产品质量安全检测中心 , 沈阳 营口 115009)
摘要 : 报道草莓中黄酮类物质含量的测定方法 , 并比较了总抗氧化成分与抗氧化活性 (DPPH , FRAP) 之
间的相互关系。黄酮类物质的水解随着 HCl 浓度和水解时间的不同发生较大的差异 , 结果表明 , 总多酚类
物质和总黄酮类物质之间有很高的相关关系 , 总多酚类物质和总黄酮类物质对 DPPH 有很高的相关关系 ,
而且总多酚类物质和总黄酮类物质对 FRAP的相关关系各为 r= 0 .958 , P < 0 .05 和 r= 0 .936 , P < 0 .05 , 从
结果可以推测 : 草莓体现出很强的抗氧化活性 , 这与草莓中的总多酚类物质成分密不可分。
关键词 : 草莓 ; 水解浓度 ; 水解时间 ; 总多酚类物质 ; 总黄酮类物质 ; DPPH ; FRAP
中图分类号 : S 482.4 + 4 文献标识码 : A 文章编号 : 0253 - 2700 (2008) 01 - 125 - 04
Quantification of Flavonoid Compounds from Strawberry
( Fragaria ananassa) and Correlation Effects
with Antioxidant Activities
ZHENG Hu-Zhe
1 , 2
, LEE Hye-Ryun
1
, CUI Chun-Lan
2
, HWANG In-Wook
1
,
KWON Sun-Young1 , CHUNG Shin-Kyo1 *
(1 Department of Food Science and Technology, Kyungpook National University, Daegu 702 - 701 , Korea;
2 Agricultural Products Analysis Center, Liaoning Agricultural College, Yingkou 115009 , China)
Abstract: The amounts of flavonoid (myricetin, quercetin and kaempferol) , antioxidant contents (total phenolic and total
flavonoid) and antioxidant activities (DPPH and FRAP) were analyzed in strawberry . Quantitative analysis of conjugated
flavonoid contentswere obtained after different hydrolysis concentrationand reaction period . The highest yields of myricetin
and quercetin werefound with 1 .0M HCl and a reaction period of 0.5 hr, however, for kaempferol was 1 .0M HCl and a
reaction period of 1hr, respectively . In the study, we also estimated the correlation coefficient of TPC , TFC, DPPH and
FRAP . In addition, a positive correlation was observed ( r = 0 .980 , P < 0.05) between TPC and TFC, TPC and TFC are
correlatedto the DPPH activity (r= 0 .913 , P < 0 .05 and r= 0 .899 , P < 0 .05 , respectively) , and to the FRAP activity ( r
= 0.958 , P < 0.05 and r= 0 .936 , P < 0.05 , respectively) , respectively . Theseresults pointedout that strawberrygeneral-
ly possesses a high level of antioxidant activities, which could be linked to the levels of phenolic compounds in thefruit .
Key words: Strawberry; Hydrolysis concentration; Reaction period; Antioxidant contents; Antioxidant activities; Correla-
tion coefficient
Strawberry fruits, with it special sweet, sour taste and ex-
quisiteflavor, especially have previously been shown to contain
antioxidant compounds such as flavonoid ( myricetin, quercetin
and kaempferol ) and phenolic acids, which provide protection
against harmful free radicals (Vinson et al. , 2001 , Cai et al. ,
2004 , Jose et al. , 2007 ) . Flavonoids have been detected in
云 南 植 物 研 究 2008 , 30 (1) : 125~128
Acta Botanica Yunnanica
? ?Author for correspondence; E-mail : kchung@ knu. ac.kr
Received date: 2007 - 05 - 24 , Accepted date: 2007 - 07 - 10
作者简介 : 郑虎哲 (1974 - ) 男 , 农学博士 , 主要从事食品分析研究。
many studies with plants, measured by after acid hydrolysis, be-
causemost flavonoids founded in plants are conjugated to sugars
as glycosides, hydrolysis of all glycosides to aglycones offers a
practical method for the quantitativedetermination of flavonoids in
plant (Hertog and Peter, 1992; Alan et al. , 1997) .
To the best of the author′s knowledge, the flavonoids agly-
cones in strawberry have not yet been estimated according differ-
ent experiment designof hydrolysis concentration and reaction pe-
riod . Furthermore thecorrelation among antioxidant contents such
as total phenolic content (TPC) , total flavonoid content (TFC) ,
andfreeradical scavengingactivity of DPPH, FRAP also havenot
been reported . The objectives of this study were 1) to optimize
themethods of extraction and hydrolysis of flavonoids conditions
and 2) to determineDPPH and FRAP activity to estimateantioxi-
dant activities and their correlations with TPC and TFC in straw-
berry fruit .
Materials and Methods
Strawberry ( Fragaria ananassa Duch .) was purchasedfrom
the local market in Dae-gu Korea .
Extraction and hydrolysis fruit for flavonoid aglycones analy-
sis were obtained by different reaction and acid concentration .
And thetreated sample was dissolved with methanol and then fil-
tered through a0 .45μmmembranefilter for HPLC analysis .
The total phenolic content (TPC) and DPPH was determined
accordingCai et al. (2004) , measurement of total flavonoid cont-
ent (TFC) and FRAP was determined according to Faria et al.
(2005) with somemodifications .
Results and Discussion
Weestimated the optimum extraction and hydrolysis condi-
tions for quantifyingthefruit of strawberry, becausethe complete-
ness of hydrolysis largely depended on the type of glycosides .
Four hydrochloric acid concentrations were tested ( 0 . 5 , 1 .0 ,
1 .5 and 2 .0 mol?L) , andthe reaction period was varied (0 .5 , 1
and 2 hrs) in the procedure described under extraction and
hydrolysis . The influence of acidconcentrationand reaction peri-
od correspondingaglycone yield is presented in table1 .
In our study, RP-HPLC coupled with UV-VIS Detector was
employed to separate, identify and quantify favonoid aglycones in
strawberry fruit ( Fig . 1 ) . In this study, the highest yields of
myricetin and quercetin werefound with 1 .0 mol?L HCl and are-
action period of 0.5 h, however, for kaempferol was 1 .0 mol?L
HCl and a reaction period of 1 h, respectively . After 2 hrswith 2
mol?L HCl concentration, a loss of up to 50.3 % and 41 .7% of
myricetin and quricetin was observed compare to the optimum
conditions, respectively ( Table 1 ) . These findings supported
those of the study by Alan et al. ( 1997 ) who reported that
cooking will fall in quercetin and myrecitin content, boiling pro-
duced even bigger reduction in tomatoes and onions . All thesere-
sults indicated that prolongedor shortened extraction and hydroly-
sis showed a decrease the flavonol contents in strawberry .
Table 1 Quantification data for optimization of hydrolysis conditions
in strawberry fruit ( 100 mg g - 1 fresh weight)
HCl Conc .
( mol?L )
time
( h) Myricetin Quercetin Kaempferol Total
0 ?. 5
0 G. 5
1
2
4 ?. 48
4 .63
4 ?. 13
5 +. 95
6 +. 21
6 +. 07
N .Da
1 . 48
1 . 32
10 H. 43
12 H. 32
11 H. 52
1 ?. 0
0 G. 5
1
2
5 ?. 09
4 .69
3 ?. 31
6 +. 60
5 +. 89
5 +. 34
1 . 45
1 . 92
1 . 12
13 H. 14
12 [. 5
9 6. 77
1 ?. 5
0 G. 5
1
2
4 ?. 89
3 .27
2 ?. 86
6 +. 12
5 +. 38
3 +. 66
1 . 55
1 . 75
1 . 66
12 H. 56
10 [. 4
8 6. 18
2 ?. 0
0 G. 5
1
2
3 ?. 88
3 .06
2 ?. 56
5 +. 02
4 +. 23
2 +. 75
1 . 77
1 . 67
N .Da
10 H. 67
8 6. 96
5 6. 31
a N .D ., Not detected .
Fig . 1 Chromatograms of flavonoid aglycones, strawberry
extracts and hydrolysis with 1 .0 mol?L HCl
and a reaction period of 1 h
M : myricetin; Q: quercetin; K : kaempferol
TheTPC and TFC in the strawberry fruits in methanol ex-
traction showed the higher value of TPC ( 4575.8 ± 80 .8 mg
GAE?100 g F . W .) and TFC ( 430 .7 ± 28 .5 mg QE?100 g
F .W .) compare to dichloromethane extraction of TPC ( 41 .4±
5 .3 mg GAE?100 g F . W .) and TFC (3 . 8±2 .7 mg QE?100 g
F .W .) , respectively . Our result was agreement with those re-
ported by Kriengsak et al. ( 2006 ) , who showed that TPC in
methanol extraction is veryhigher comparetodichloromethaneex-
traction . All these results indicate that methanol extraction is a
better extraction solvent for the extraction of both TPC and TFC .
Themethanol extraction exhibited a concentration-dependent
621 云 南 植 物 研 究 30 卷
Fig . 2 Free radical scavenging activity ( DPPH ) of strawberry
means±SD, n= 3 . Bars represent standard error
Fig . 3 Ferric reducing antioxidant power ( FRAP) of strawberry
means±SD, n= 3 . Bars represent standard error
DPPH radical scavenging activity, which was higher than that of
thepositivecontrol , trolox, the scavenging effect increased with
the increasing concentrations from0 .8 - 8 .0 mg?ml, it was found
to be over 90 .8% in8 .0 mg?ml concentration, which is signifi-
cantly higher than that of gallic acid ( 82 .9 % ) and trolox
(30 .4% ) at the same concentration of 150 μmol ( Figure 2 ) .
These results were agreement with Jose et al. ( 2007) who indi-
cated that native cultivated strawberries ( F . vesca) were 2 .5
times more active than in theTEAC assay (Trolox equivalent an-
tioxidant capacity) .
Figure3 clearly showed that the FRAP of methanol extract
of strawberry had reducing power of 191 .5± 7 .2 TE μmol?mg
extract . Thiswas slight higher than that of ascorbic acid (184 .5
±5 .6 TEμmol?mg) , but lower than that of gallic acid (447 .7
±5 .9 TEμmol?mg) within a concentration of 150μm . Accord-
ing to its high value, it could be considered that compound was
good electron donors and could terminate oxidation chain reac-
tions by reducing the oxidized intermediates into the stable form .
Recently studies have suggestedthat the antioxidant contents
and antioxidant?freeradical scavengingactivities havethe positive
effect ( Jose et al. , 2007 , Kriengsak et al. , 2006 ) . In our
study with the strawberry fruit, a positive correlation was ob-
served (r= 0 .980 , P < 0 .05) between TPC and TFC in metha-
nol extraction, however, there was no significant correlation in
dichloromethane extraction ( data not shown) . Furthermore, TPC
andTFC are correlated to the DPPH activity ( r = 0 .913 , P <
0 .05 and r= 0.899 , P < 0 .05 , respectively) and to the FRAP
activity ( r = 0 .958 , P < 0 .05 and r = 0 .936 , P < 0 .05 , re-
spectively) was observed . In addition, a positive correlation was
also observed ( r = 0 .947 , P < 0 .05 ) between DPPH and
FRAP . Our results indicated that TPC showed the highest corre-
lation with TFC . It could be explain that phenolic and flavonoid
compounds, which are known as hydrophilic antioxidants, are
secondary metabolites that are most abundant in fruits, which
positively correlated with the oxygen radical absorbance capacity
(ORAC) . In addition, most techniques used for determiningan-
tioxidant activity, showed high correlation with TPC and TFC in
different free radical scavenging activities . All these results were
agreement with Vinson et al. ( 2001) who reportedthat strawber-
ry generally possesses a high level of antioxidant activity, which
could be linked to the levels of phenolic compounds in the fruit .
Furthermore, our results were supported by Gil et al. ( 2002 ) ,
whofound high correlation betweenantioxidant activities andtotal
phenolic content in nectarines, peaches and plums, and they
demonstrated that there was no correlation between ascorbic acid
and antioxidant activity as determined by DPPH or FRAP assays .
Strawberry fruits contain a group of natural antioxidants that
could have not only a high antioxidant activity but also a good
combination or mixture of antioxidants, the supplementation of
these natural antioxidants through a balanced diet containing
enough fruits could be much more effective and also economical
than the supplementation of synthetic preservatives .
References:
Alan ?Crozier, Michael EJL , MoragSM et al. , 1997 . Quantitative analys-
is of the flavonoid content of commercial tomatoes, onions, lettuce,
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Cai ?YZ, Luo Q, Sun M et al. , 2004 . Antioxidant activity and phenolic
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* * * * * * * * * * * * * * *
〔上接 114 页〕
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821 云 南 植 物 研 究 30 卷