Antioxidant and anti-diabetic effects of Ixeris strigosa extract

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ABSTRACT

Purpose: Ixeris strigosa (IS) is a perennial plant that commonly grows in meadows. The leaves and roots of IS have been used in medicine as a sedative. This study evaluated the antioxidant and carbohydrate-digestive-enzyme inhibitory effects of IS to determine its potential as an essential antioxidant and glycemic inhibitor for type 2 diabetics.

Methods: The antioxidative and α-amylase and α-glucosidase inhibitory activities were examined using the water extracts (ISW), ethanol extracts (ISE), and solvent fractions from IS. The antioxidative activities were measured using in vitro methods by measuring the 1,1-diphenyl-2-picrylhydrazyl and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activity.

Results: Investigations of the total polyphenol, flavonoid content, in vitro antioxidant activity, and α-amylase and α-glucosidase inhibitory activities of the IS extract showed that the ISE had higher total phenolic and flavonoid contents than the ISW, as well as high antioxidant activity. The ethanolic extracts of IS (70%) had an α-amylase inhibitory activity of 78.55%.

The ethyl acetate fraction (90.56%) showed higher α-glucosidase inhibitory activity than the positive control, acarbose (83.01%).

Conclusion: Among the ISE fractions, the ethyl acetate and butanol fractions showed the best digestive enzyme inhibitory activity. Moreover, the antioxidant activity of the extract and the carbohydrate, α-amylase, and α-glucosidase inhibitory effects showed a stronger correlation with the total phenol and flavonoid contents compared to the ISW. As a result, the antioxidant and digestive enzyme inhibitory activities of high ISE are due to the phenolic compounds, particularly the flavonoid compounds. Therefore, ethyl acetate and butanol fractions of the 70% ethanol extract are excellent anti-diabetic functional materials.

Keywords: Ixeris strigosa, antioxidant, α-amylase, α-glucosidase

Research Article

Antioxidant and anti-diabetic effects of Ixeris strigosa extract

Yun-Jeong Ji ^1,*, Eun Young Lee ^1,*, Ji Yeon Lee ^1,2, Kyung Hye Seo ¹, Dong Hwi Kim ¹, Chun Geon Park ¹, and Hyung Don Kim ¹

1 Department of Herbal Crop Research, National Institute of Horticultural & Herbal Science, Eumsung 27709, Korea

2Department of Food Science and Biotechnology, Chungbuk National University, Cheongju 28644, Korea

선씀바귀 추출물의 항산화 및 항당뇨 효과

지윤정^1,*, 이은영^1,*, 이지연^1,2, 서경혜¹, 김동휘¹, 박춘근¹, 김형돈¹

1농촌진흥청 인삼특작부

2충북대학교 식품공학과

Received: Apr 14, 2020 Revised: May 4, 2020 Accepted: May 18, 2020 Correspondence to Hyung Don Kim

Department of Herbal Crop Research, National Institute of Horticultural & Herbal Science, 92 Bisan-ro, Eumsung 27709, Korea.

Tel: +82-43-871-5783 E-mail: [email protected]

*These authors contributed equally to this article.

creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

ORCID iDs Yun-Jeong Ji

https://orcid.org/0000-0003-1182-2328 Eun Young Lee

https://orcid.org/0000-0002-8311-5991 Ji Yeon Lee

https://orcid.org/0000-0002-3622-7392 Kyung Hye Seo

https://orcid.org/0000-0002-8155-8051 Dong Hwi Kim

https://orcid.org/0000-0002-2129-7056 Chun Geon Park

https://orcid.org/0000-0003-4177-6270 Hyung Don Kim

https://orcid.org/0000-0003-0993-4347

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Funding

This work was carried out with the support of “Cooperative Research Program for Agriculture Science and Technology Development (Project No. PJ01361602)” and the RDA Fellowship Program of National Institute of Horticultural and Herbal Science, Rural Development Administration, Republic of Korea.

Conflict of Interest

There are no financial or other issues that might lead to conflict of interest.

서론

최근식생활과생활습관등의변화로각종만성질환이증가하고있으며그중대사성질환인

당뇨병 (diabetes mellitus)은전세계적으로급증하고있다^.국제당뇨병연맹은현재약⁴억여

명인당뇨병환자가²⁰⁴⁵년에는⁷억명에달할것으로예측하고있다^[1].우리나라국민영양

조사결과에서성인만³⁰세이상당뇨병유병률은²⁰⁰¹년^8.9%에서²⁰¹⁸년^12.9%로매년꾸

준히증가하고있다^[2].당뇨병은그기전에따라췌장에서인슐린이전혀분비되지않아서

발생한제¹형당뇨병과인슐린저항성이증가하여발생하는제²형당뇨병으로나뉜다^[3].

당뇨병의치료법은인슐린을투여하는방법과혈당강하제를복용하여혈당을조절하는방 법이있다^.가장일반적인형태인제²형당뇨병의치료방법으로경구혈당강하제복용법

은당분해에관여하는효소들을저해하는물질을이용한다^[4].당의분해에관여하는효

소중에서^α-amylase와 α-glucosidase는전분과글리코겐소화에중요한효소이며식후포도

당농도를조절하는데중요한역할을한다^.일반적으로전분은^α-amylase에의해^maltose와

dextrin으로분해되며^,이후에 α-glucosidase가포도당으로전환시켜혈당수준을높인다^[5].

따라서^,제²형당뇨병치료에서 α-amylase 및 α-glucosidase의억제는식후혈당을완화시키

는효과적인방법이다^.

α-amylase 및 α-glucosidase를억제하기위한치료제로 acarbose, miglitol 및^voglibose가있다^.그 러나치료제에대한부작용으로복부팽만^,설사등위장관련증상이나타나사용이제한되고

있다^[6].따라서최근다양한소화효소억제효과를가진천연물소재들을탐색하고그생리

활성물질들을당뇨병의예방과치료에이용하려는연구가다양하게이루어지고있다^[7,8].

식물에서유래된페놀화합물은소화효소의활성을억제시킬수있는잠재적활성물질이 라는것을선행연구들에서입증하였으며^,소화효소와페놀화합물의결합구조에의해안 정성이나활성이변화될수있다는것이확인되었다^[9,10].천연물질에서추출한 quercetin, ferulic acid, chlorogenic acid, luteolin 등이소화효소억제효능을가진다고보고되었다^[11].

선씀바귀⁽Ixeris strigosa [IS])는초원에흔히자라는여러해살이풀로높이는^{20–40 cm}이다^.씀 바귀와비슷하게생겼으나위로곧게자라고꽃의색깔이다르며^,어린잎은식용하고민간에

서진정제등의약으로쓰였다^[12].상대적으로잘알려졌으며많은연구가이루어진씀바귀

에비해선씀바귀에대한생리활성연구는거의없는실정이다^.이에현재까지알려진씀바

귀성분들의생리활성연구결과를기반으로선씀바귀물추출물^(ISW)과선씀바귀^70%에

탄올추출물^(ISE)및용매분획물⁽헥산 [hexane], 클로로포름 [chloroform], 에틸아세테이트 [ethyl acetate], n-부탄올 [water standard n-butanol])의in vitro항산화활성과항당뇨활성을조 사하여선씀바귀의항당뇨기능성소재로의이용가능성을알아보고자하였다^.

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연구방법

선씀바귀추출물제조

실험에사용된선씀바귀시료는²⁰¹⁸년충북음성군인삼특작부포장에서수확한것으로지

상부를동결건조기 (PVTFD 50R; Ilshinbio, Seoul, Korea)에서건조하여분말화하였다^.추출을

위해건조된선씀바귀지상부^{50 g}을^70%에탄올과물⁽시료와용매비율^1:10)로실온에서²⁴

시간동안³번반복추출하였다^.추출용액은여과해서농축하고동결건조하였다^.각추출물 은^{100 mg/mL}의농도로 dimethylsulfoxide (DMSO; Sigma-Aldrich, St. Louis, MO, USA)에녹여 희석하여항산화활성및항당뇨실험에사용하였다^.

선씀바귀용매분획물제조

선씀바귀추출물의용매분획물은^{Fig. 1}의순서로순차적용매분획하여제조하였다^[13].순

차적용매분획은^70%에탄올추출물^{2 g}을물^{200 mL}에재용해한후분획깔데기 (separatory

funnel)에넣고헥산^,클로로포름^,에틸아세테이트^{, n-}부탄올의순서로가하여분획하였다^.

분획후남은물층을포함하여⁵개의분획물은감압농축후^DMSO에재용해하여시료로사

용하였다^.각용매별수율은에틸아세테이트^{3.85%, n-}부탄올^14.5%,헥산^13.5%,클로로포 름^15.7%,물^51.5%로확인되었다^.

총페놀(total phenol compounds content)과플라보노이드(total flavonoid compounds content) _함량_측정

총페놀함량측정은^Folin과 Denis [14]의방법에따라분석하였다^.추출물 500 µL (100 µg/mL) 을 2 N Folin-Ciocalteu 시약^{50 µL}와³분간혼합하였고 sodium carbonate anhydrous 용액¹⁰⁰ µL를넣었다^{. 1}시간후^,흡광도는 multi-plate reader (Biotek, Winooski, VT, USA)를사용하여

725 nm에서측정하였다^.총플라보노이드함량은 Pourmorad 등^[15]의염화알루미늄비색법

을약간수정하여진행하였다^.각추출물 (100 µg/mL) 150 µL를^10%알루미늄염화물용액¹⁰

µL, 1 M 아세트산칼륨용액^{10 µL}및증류수^{280 µL}와혼합하였다^.혼합물을실온에서³⁰분

동안반응시키고 multi-plate reader를사용하여^{415 nm}에서흡광도를측정하였다^.선씀바귀

Hexane fraction Chloroform fraction Ethyl acetate fraction

n-butanol fraction 70% ethanolic extract (with water)

Hexane added to the extract with water and separated Chloroform added to the remaining water and separated Ethyl acetate added to the remaining water and separated Saturated n-butanol added to the remaining water and separated

Aqueous fraction

Fig. 1. Schematic diagram for the preparation of solvent fractions from 70% ethanolic extract of Ixeris strigosa.

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추출물의총페놀함량은 galic acid의용량 (mg GAE/g)으로총플라보노이드함량은^catechin acid의용량 (mg CAE/g)으로표시하였다^.

2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS⁺) _라디칼

소거측정

ABTS 라디칼소거능은^Re등^[16]의방법을변형하여측정하였다^.증류수에 7.4 mM ABTS 암

모늄염과^{2.6 mM}칼륨과황산염을함유한 ABTS (Sigma Chemical Co., St. Louis, MO, USA) 용 액을준비하였다^.선씀바귀추출물시료^{20 µL}와^ABTS용액^{180 µL}를섞어실온으로암실에 서³⁰분간배양하였다^.흡광도는^{734 nm}에서 multi-plate reader를사용하여측정하였으며대 조군으로에탄올을첨가하였고양성대조군으로 ascorbic acid (AA; Sigma-Aldrich)를사용하 여비교^,산출하였다^.소거효과는다음식에따라계산되었다^.반^-최대억제농도^(IC50)는

50% 억제를나타내는샘플농도의^ABTS⁺라디칼소거활성을결정하였다^.

1,1-diphenyl-2-picrylhydrazyl (DPPH) 라디칼소거능측정

DPPH 라디칼소거능검정방법^[17]을약간변형하여사용하였다^{. 95%}에탄올에^{DPPH 300}

µM을함유한^DPPH용액을제조하였다^.다음으로시료^{50 µL}와^DPPH용액^{200 µL}를섞어

실온에서알루미늄호일로덮어암실에서³⁰분간두었다^.흡광도는^{517 nm}에서 multi-plate

reader를사용하여측정하였으며대조군에는에탄올을첨가하였으며^{, AA}를양성대조군으

로사용하였다^.소거효과는다음식에따라계산되었으며^50%억제를나타내는^IC⁵⁰로추출 물의자유라디칼소거활성을비교하였다^.

α-glucosidase 및α-amylase의억제활성측정

선씀바귀추출물의소화효소활성억제효과를평가하기위하여 α-glucosidase 및 α-amylase 활 성비색분석키트 (BioVision K938, K482; BioVision, Milpitas, CA, USA)를이용하여측정하였 다. α-glucosidase 활성은 10 μL α-glucosidase를각^well에첨가하고^,분석완충액을총부피⁶⁰ μL/well로첨가하였다^{. 20 μL}의 α-glucosidase 기질혼합물을각^well에첨가하고^{, 410 nm}에서 1시간동안흡광도를판독하였다^{. α-}아밀라아제활성은분석을위해, acarbose (1,000 μg/mL) 를 96-well plate에첨가하고희석된샘플^{50 μL}을각각의^well에첨가하고^{, 50 μL}의^α-amylase 를넣고빛을차단하여상온에¹⁰분간활성화시켰다^{. 50 μL}의기질혼합물을넣고^{, 20}분간흡

광도^{410 nm}에서판독하였다^.시료와양성대조군인^acarbose는 1,000 μg/mL의농도로사용

하였다^.

ABTS 라디칼 소거능 (%) = �1 − 시료흡광도

대조구흡광도� × 100

전자공여능 (%) = �1 − 시료흡광도

대조구흡광도� × 100

α − glucosidase 및 α − amylase 저해율 (%) = 1 − �시료처리구의 흡광도

대조구의 흡광도 � × 100 α-glucosidase 및^α-amylase

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통계처리

모든실험은³회반복실시하였으며^,평균^{(mean) ±}표준편차 (standard deviation)로표기하 였다^.실험결과는 SPSS package를이용하여분산분석검정을수행하였으며^,각처리군간의 유의성검정은 Duncan's multiple range test로 p < 0.05 수준에서실시하였다^.상관관계분석 은 SPSS (version 21; IBM Inc., Armonk, NY, USA)를이용하여 Pearson's correlation coefficient 로실시하였다^.

결과

수율, 총폴리페놀및총플라보노이드함량

선씀바귀추출물의총페놀함량은 gallic acid를기준물질로^,총플라보노이드함량은^{(+) −}

catechin을기준물질로측정하였다^.선씀바귀에함유되어있는^ISW와^ISE의총페놀함량은

각각 3.18 mg GAE/g, 27.46 mg GAE/g으로ÎSE가ÎSW보다⁹배정도많았다^.선씀바귀추출물의 플라보노이드함량도각각 0.19 mg CAE/g, 3.89 mg CAE/g로ÎSE가ÎSW보다²⁰배정도높게나 타났다 (Table 1). 추출방법에따른선씀바귀의ÎSW와ÎSE수율은각각^35.4%와^34.3%로두용 매간에유의적인차이는없었다^.

라디칼소거활성

선씀바귀추출물의항산화효과를알아보기위하여^DPPH라디칼소거활성과^ABTS⁺라디칼

소거활성을비교한결과는^{Table 1}과같다^.항산화제로잘알려진^AA을양성대조군으로하

여분석한결과대조구인ÂA의^{DPPH IC}⁵⁰값은 5.91 µg/mL이었으며^{, ISW}와ÎSE의^{DPPH IC}⁵⁰값 은각각 2,099 µg/mL, 96.3 µg/mL로나타났다 (p < 0.05). ABTS⁺소거활성을비교한ÎC50값은대 조구인ÂA가 4.36 µg/mL, ISW는 543.3 µg/mL, ISE는 22.79 µg/mL로ÎSE가ÎSW보다소거활성이 강한것으로나타났다 (p < 0.05).

α-glucosidase 및 α-amylase 저해효과

선씀바귀추출물의 α-glucosidase와 α-amylase 활성저해효과를측정한결과는^{Table 2}에서보

는바와같다^.양성대조군인 acarbose 1 mg/mL과비교하였을때^acarbose는^99%억제효과를 보였으며 ISW 1 mg/mL는^39%억제하였고 ISE 1 mg/mL는^75%의 α-glucosidase 저해활성을

나타냈다^.선씀바귀추출물의 α-amylase 활성저해효과역시^ISE가^74%억제효과를보인반

면^ISW는^13%의저해효과를보였다^{. ISE}의소화효소저해활성이^ISW보다우수함을확인하

고^{, ISE}에있는소화효소저해능을가지는물질들의특성을파악하기위해^ISE의용매분획물

을제조하여이후실험을진행하였다^.

Table 1. Antioxidant activity of Astragalus membranaceus Ixeris strigosa extract

Sample TPC (mg GAE/g) TFC (mg CAE/g) ABTS DPPH

IC50 value (μg/mL)

Ascorbic acid 4.30 ± 0.30 5.90 ± 0.10

ISW 8.98 ± 0.00 0.53 ± 0.00 543.26 ± 12.80 2,099.30 ± 83.90

ISE 80.07 ± 0.70 11.36 ± 0.10 22.79 ± 1.30 96.63 ± 1.10

All data are presented as the means ± SD of triplicate determinations.

ISW, Ixeris strigosa water extracts; ISE, Ixeris strigosa 70% ethanol extracts; TPC, total phenol compounds content; GAE, gallic acid equivalents; TFC, total flavonoid compounds content; CAE, catechin acid equivalents;

ABTS, 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid; DPPH, 1,1-diphenyl-2-picrylhydrazyl.

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ISE 계통분획물^{1 mg/mL}의 α-glucosidase 저해활성은^{Table 3}과같이나타났다^.에틸아세테 이트분획물에서^90.56%로가장높았고그다음은부탄올^88.67%,물^28.30%순으로나타나 대표적인 α-glucosidase 저해제인^acarbose가나타내는활성^(85%)보다높게나타났다^{. ISE}계 통분획물의 α-amylase 저해활성은에틸아세테이트분획물에서^93.31%로가장높았고그다 음은부탄올^89.86%,헥산^35.52%,클로로포름^29.66%,물^3.02%순으로나타났다 (Table 3).

ISE 용매분획물의소화효소저해활성실험에서에틸아세테이트분획물과부탄올분획물이 활성이높은것으로보아^,선씀바귀의페놀화합물들이소화효소저해에결정적인역할을하 는것으로판단할수있었다^.

상관관계

선씀바귀추출물의폴리페놀및플라보노이드함량^,항산화와 α-glucosidase 저해활성및

α-amylase 저해활성간의상관관계가있는지를검토해보았다^{. DPPH}와^ABTS⁺는^IC⁵⁰값으

로상관관계를분석하였다^.선씀바귀추출물의항산화활성및소화효소저해활성간의상

관관계를분석한결과^{Table 4}와같이나타났다^.먼저폴리페놀 1.000 (p < 0.01), 플라보노이

드 −1.000 (p < 0.01) 와 α-amylase −1.000 (p < 0.01) 저해활성이가장높은상관관계를나타내

었다. α-glucosidase 저해활성과폴리페놀과플라보노이드함량, DPPH, ABTS 라디칼소거능

Table 3. Inhibitory activity of fractions from Ixeris strigosa extract on α-glucosidase and α-amylase Sample (1 mg/mL) Inhibition of α-glucosidase and α-amylase activity (%)

α-glucosidase α-amylase

Acarbose 85.3 ± 2.9^c 98.1 ± 1.2^c

Ethyl acetate fraction 91.7 ± 1.2^c 93.3 ± 4.4^c

Butanol fraction 87.3 ± 2.8^c 89.8 ± 8.1^c

Water fraction 35.7 ± 9.5^b 3.0 ± 1.5^a

Chloroform fraction - 29.6 ± 16.6^b

Hexane fraction 11.3 ± 19.5^ab 35.5 ± 15.7^b

Means in the same column not sharing a common letter are significantly different (p < 0.05) by Duncan's multiple range test.

Table 4. Correlation among factors affecting of antioxidant components and effects

Factors¹⁾ TPC (mg GAE/g) TFC (mg CAE/g) ABTS (IC50 value) DPPH (IC50 value) α-glucosidase α-amylase

TPC (mg GAE/g) 1.000 1.000^** −1.000^** −0.999^** 0.916^* 0.916^**

TFC (mg CAE/g) 1.000 −1.000^** −0.999^** 0.914^* 0.917^**

ABTS (IC50 value) 1.000 0.998^** −0.908^* −0.976^**

DPPH (IC50 value) 1.000 −0.932^** −0.975^**

α-glucosidase 1.000 0.887^*

α-amylase 1.000

TPC, total phenol compounds content; TFC, total flavonoid compounds content; ABTS, 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid; DPPH, 1,1-diphenyl- 2-picrylhydrazyl.

1)Total contents of phenolic acid; ABTS and DPPH was analyzed by IC50 value; Inhibition of α-glucosidase and α-amylase activity.

Significance was determined using SPSS by Pearson's correlation coefficient: ^*p < 0.05; ^**p < 0.01.

Table 2. Measurement of α-glucosidase and α-amylase inhibitory activities

Sample (1 mg/mL) Inhibition of α-glucosidase, α-amylase activity¹⁾ (%)

α-glucosidase α-amylase

Acarbose 89.6 ± 1.7^b 99.0 ± 1.3^c

ISW 39.2 ± 14.3^a 13.5 ± 0.6^a

ISE 78.1 ± 3.9^b 74.5 ± 11.6^b

Values are means of triplicate determinations ± SD. Means with different letters on the same column are significantly different at p < 0.05 by Duncan's multiple range test.

ISW, Ixeris strigosa water extracts; ISE, Ixeris strigosa 70% ethanol extracts.

1)α-glucosidase, α-amylase inhibition activity (%) of Ixeris strigosa extract and acarbose was measured at 1 mg/mL.

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IC50값은각각 0.946 (p < 0.01), −0.946 (p < 0.01), 0.950 (p < 0.01), 0.950 (p < 0.01)로높은상관 관계를나타내었다^.결과적으로선씀바귀추출물은항산화활성과소화효소저해활성간에 모두높은상관관계를나타내었다 (p < 0.01). 다시말해^,선씀바귀의페놀화합물^,특히플라 보노이드화합물들이항산화및소화효소저해활성이뛰어나^{, ISE}가^ISW에비해높은항산 화활성및소화효소저해능을갖는데결정적인역할을하는것으로판단된다^.

고찰

당뇨병은대사장애로식후혈당수준의비정상적인증가를특징으로한다^[18].음식섭취후 혈당수준을효과적으로제어하기위하여천연공급원으로부터얻은^acarbose및 voglibose 등이당뇨병의치료에임상적으로사용되어왔다^[19].그러나위장관련부작용으로인한약 물의안전성문제가제기되고있어치료의효과를높이고부작용이없는천연물을이용한대

안적소재들을찾아야한다^[20].따라서본논문에서는천연물소재인선씀바귀를이용하여

항당뇨를위한탄수화물소화효소억제효과를검증하였다^.

당뇨에의한합병증발병및악화요인중하나로고혈당증에의한활성산소종 (reactive oxy-

gen species) 생성이있다^.이는산화적스트레스발생에의한자유라디칼 (free radical)의과

다한생성과항산화방어체계의활성저하가원인이된다^[21].식물의²차대사산물인폴리 페놀계물질중플라보노이드는가장널리분포되어있는페놀화합물로항산화^,항균^,항염 증^,항알레르기및항암등다양한생물학적효과를나타내며^,자유라디칼소거와산화방지 효과에서천연항산화제로작용한다^[22].본연구에서선씀바귀추출물에함유되어있는총 페놀함량은ÎSE가ÎSW보다¹⁰배정도많았다^.선씀바귀추출물의플라보노이드함량도ÎSE 가ÎSW보다²⁰배이상높게나타났다^.이실험의결과는추출방법에따라총폴리페놀함량

과성분에차이가난다는^[23]의보고와유사한결과를보였다^.선씀바귀추출물은씀바귀에

탄올추출물의총페놀함량보다²⁰배가높았고플라보노이드함량은¹⁰배더높았다^[24].그

리고흰씀바귀뿌리보다총페놀함량이더높게나타나^[25]다른씀바귀종류들과비교했을

때총페놀함량과플라보노이드함량은높게나타났다^.

DPPH 라디칼소거활성은페놀화합물의항산화활성지표가되며^,자유라디칼은환원능력

이클수록항산화활성및활성산소에대한소거활성을기대할수있다^[26].본연구에서선

씀바귀추출물의항산화효과를알아보기위하여^DPPH라디칼소거활성과^ABTS⁺라디칼소

거활성을비교한결과양성대조군으로사용된^AA보다는낮은항산화활성이지만^ISW보다 ISE의항산화력이²⁰배이상높은것으로조사되었다^{. Kang}등 [27], Shin과^{Lee [28]}는에탄올 추출물이물과유기용매의적절한혼합에의해페놀성화합물의용출이많고이들페놀화합

물이^DPPH라디칼소거활성을높이는데영향을미친다고하였다^.페놀성화합물의농도가

높을수록자유라디칼의소거능이높아지며유기용매가혼합되어있는경우페놀성물질의 용출이더용이하다는이상의결과들로미루어볼때본연구에서도페놀화합물이^DPPH라 디칼소거활성을높이는데영향을미친것으로판단된다^.

탄수화물섭취후 α-amylase 및 α-glucosidase 등의소화효소활성억제는혈당의증가를감소시

키거나혈당상승을지연하는효과가있어^II형당뇨병과관련된고혈당증의관리에필수전략

(8)

으로여겨진다^[29].선씀바귀추출물의 α-glucosidase 활성저해효과를측정한결과^{Fig. 2}에서 와같이양성대조군인âcarbose와비교하였을때âcarbose는^89%억제효과를보였으며ÎSW 는^39%억제하였고ÎSE는^78%의 α-glucosidase 저해활성을나타냈다^{. Jeong}등^[30]의약용식

물의항당뇨활성연구에서상엽^70%에탄올추출물이^acarbose보다높은 α-glucosidase 저해

활성을보여혈당강하물질로기대할수있다고보고한바^,본연구의^ISE는^acarbose보다는

낮았으나 α-glucosidase 저해활성이우수함을확인할수있었다^{. Kim}등^[31]은쓴메밀물추

출물과^70%에탄올추출물의 α-glucosidase 활성을측정한결과^70%에탄올추출물에서는농

도의존적으로저해활성이높아지는경향을보였으나^,물추출물에서는저해활성이없다 고하였는데본연구의결과와비슷한경향이었다^{. Lee}등^[32]의벌개미취추출물의^α-gluco-

sidase 저해능은용매의에탄올함량이높을수록커지는경향이나타났다고하였다^.선씀바

귀추출물의 α- amylase 활성저해효과역시ÎSE가^75%억제효과를보인반면ÎSW는^13%의저 해효과를보였다 (Fig. 3). 물론âcrarbose의^99%보다는낮았으나ÎSE의 α-amylase 활성저해효

과는^acarbose와통계적으로유의적차이를보이지않는수준이었다. α-amylase 및 α-glucosi-

dase 등의소화효소활성억제효과는추출물에함유된플라보노이드함량과관계가있는것

으로보아진다^.즉, quercetin과^luteolin이 α-glucosidase와^α-amylase를가역적으로느리게결

Inhibition rate (%)

0 100

40 80

60

20

b

Acarbose EtOAC BuOH W CHCl3

ab

Hxn (1 mg/mL)

c c c

Fig. 2. Inhibitory activity of the extract and fractions from IS on α-glucosidase. The final concentration of the extract and fractions from IS and acarbose were 1.0 mg/mL. Each value is expressed as mean ± SD in triplicate experiments.

IS, Ixeris strigosa; EtOAC, ethyl acetate fraction; BuOH, butanol fraction; W, water fraction; CHCl3, chloroform fraction; Hxn, hexane fraction.

Values with different alphabets are significantly different at p < 0.05 as analyzed by Duncan's multiple range test.

Inhibition rate (%)

0 150

50 100

a

Acarbose EtOAC BuOH W CHCl3

b b

Hxn (1 mg/mL)

c c c

Fig. 3. Inhibitory activity of the extract and fractions from IS on α-amylase. The final concentration of the extract and fractions from IS and acarbose were 1.0 mg/mL. Each value is expressed as mean ± SD in triplicate experiments.

IS, Ixeris strigosa; EtOAC, ethyl acetate fraction; BuOH, butanol fraction; W, water fraction; CHCl3, chloroform fraction; Hxn, hexane fraction.

Values with different alphabets are significantly different at p < 0.05 as analyzed by Duncan's multiple range test.