L/O/G/O

Antioxidant components and properties of five long-grained rice bran extractsfrom commercial available cultivars in Thailand

from Food Chemistry 111 (2008)

汇报人：胡冬梅指导老师：薛照辉副教授

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IntroductionIntroduction

Materials and methodsMaterials and methods

Results and discussionResults and discussion

1. Introduction1. Introduction

1. Lower of blood cholesterol

1. Lower of blood cholesterol

2.Decrease atherosclerosis disease2.Decrease atherosclerosis disease

3. Laxative effect 3. Laxative effect

6. Prevent urinary stones 6. Prevent urinary stones

4. Anticancer4. Anticancer

5. Restrain the melanin

5. Restrain the melanin

1. Introduction1. Introduction

rice branhigher alcoholshigher alcohols

sterolssterols

gamma-oryzanolgamma-oryzanol

tocotrienolstocotrienols

phenoliccompoundsphenolic

compounds

tocopherolstocopherols

Rice bran powder has a high nutritive value

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Mill rice grainsieve to separate grain from rice bran

Rice bran was ground, then passed through sieves heated at 100 ℃ for 15 min to inactivate endogenous lipase

Rice bran powder (10.0 g) was extracted with methanol (150 ml) for 12 h in an electrical shaker at room temperature.

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The extract was filtered through filter paper and the solvent was removed.

2. Materials and methods2. Materials and methods

44The extracts were combined ， then evaporate under vacuum using a rotary evaporator

5566The residual crude methanolic rice bran extract was weighed and stored at 20℃ under a nitrogen gas stream

RB-1RB-2RB-3RB-4RB-5

twice again

2.1 Determination of TPC 2.1 Determination of TPC

Rice bran extract was dissolved methanol.

Rice bran extract (250 µl) mix with 500µl Folin–Ciocalteu reagent and a further 6.0 ml of distilled water.

The mixture was shaken vigorously and 2.0ml Na2CO3 (15%w/v) were added and the mixture was again shaken vigorously for 2 min.

The final volume was 10.0 ml with distilled water. The mixture was left to stand for 2 h at room temperature. The absorbance at 750 nm was measured by using a UV–vis spectrophotometer

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Rice bran extract was dissolved in methanol.250µl+ distilled water 1.25 ml + 75 µl 5%NaNO2 room temperature for 6 min

step 1step 1

step 2step 2

step 3step 3

150µl of 10% AlCl3 were added. This mixture stand for a further 5 min.0.5 ml of 1 M NaOH was added.

The solution was shaken vigorously.The absorbance at 510 nm was measured with a

UV–vis spectrophotometer

2.2 Determination of TFC2.2 Determination of TFC

2.3 Determination of γ-oryzanol content 2.3 Determination of γ-oryzanol content

filter through a syringe filter

with PTFE( 聚四氟乙烯 )

Rice bran extract 100.0 mg was

dissolved in 1.0 ml of methanol

RP-HPLC

mobilephase

mobilephase

流动相：甲醇：乙腈：二氯甲烷：醋酸 (50:44:3:3 v/v/v/v)

流速： 1.0 ml/min

UV–vis detector 330 nm

2.4 Determination of total tocopherol, total tocotrienol, tocopheroland tocotrienol isomer contents

2.4 Determination of total tocopherol, total tocotrienol, tocopheroland tocotrienol isomer contents Tocopherol isomer content of rice bran

extract was determined by RP-HPLC

Agilent 1100 series RP-18 GP column流动相：甲醇：乙腈：二氯甲烷（ 50 ： 44 ： 6 ， v/v/

v ）流速： 1ml/min

荧光检测器 激发和发射波长分别为 290nm 和 330nm

0.5 ml sample solution in methanol was mixed with 2.5 ml 0.5 mM methanolic solution of DPPH.

The absorbance was measured at 517 nm against

a blank, using aUV–vis spectrophotometer

The mixture was shaken vigorously and incubated

for 30 min in the dark at room temperature.

2.5 Determination of DPPH radical-scavenging activity2.5 Determination of DPPH radical-scavenging activity

DPPHDPPH scavenging ability(%) = [1 - Absorbancesample/Absorbancecontrol]×100

Trichloroacetic acid (10%, 5.0 ml) was added to mixture, then centrifuged at 6000 g for 10 min

Rice bran extract in methanol

(2.5 ml) was mixed with 2.0 M

sodium phosphate buffer at pH

6.6 (2.5 ml).

The dilute sample was then mixed with 5.0 ml of 1% potassium ferricyanide and the mixture was incubated at 50 ℃ for 20 min.

The upper solution (5.0 ml)was

mixed with distilled water (5.0

ml) and 1.0 ml ferric chloride (1.

0%) was added

The absorbance was measured at 700 nmBHT was used for comparison

2.6 Determination of reducing power2.6 Determination of reducing power

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2.7 Determination of ferrous ion-chelating activity2.7 Determination of ferrous ion-chelating activityThe reaction mixture (2.0 ml) containedhexamine (30 mM), KCl (30 mM) and FeSO4(9 mM) was added each rice bran extract in methanol(2.0 ml) and 200µl of 1 mM TMM( 三羟甲基三聚氰胺 )

The mixture was shaken vigorously and left to stand for 3 min at roomtemperature.

Absorbance of the mixture was determined at 485 nm against a blank. (Na2EDTA ） was used for comparison.

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Rice bran extract in methanol (200 µl)

Stand in darkness at 37 ℃ for15 h

BHT was used for comparison

6.0 ml of 60% methanol were added

4.0 ml linoleic acid (10 mM) in Na3PO4 buffer (0.2 M)

Absorbance measuredat 234 nm against a blank

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2.8 Determination of lipid peroxidation inhibition2.8 Determination of lipid peroxidation inhibition

% of inhibition of lipid peroxidation =

[1-Absorbancesample/Absorbancecontrol]×100

3. Results and discussion3. Results and discussion

▲

▼ not significantly different

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3. Results and discussion3. Results and discussion

a mixture of phytosteryl and campesteryl ferulates

have antioxidant properties in many types of in vitro

model systems

Different forms oftocopherol exhibit different

antioxidative effectsT↑,δ˃γ˃β˃α

生育酚的抗氧化作用是通过传递一个氢原子到过氧化脂质

自由基从而形成脂质氢过氧化物和生育酚自由基

3. Results and discussion3. Results and discussion

BHT

RB-2

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▲ ▼

BHT˃RB-2˃RB-1˃RB-3˃RB-5˃RB-4

3. Results and discussion3. Results and discussion

BHT˃RB-2˃RB-1˃RB-3˃RB-5˃RB-4

3. Results and discussion3. Results and discussionEC50 ，半最大效应浓度

是指能引起 50% 最大效应的浓度。

3. Results and discussion3. Results and discussionNa2EDTA RB-2

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RB-5

RB-4

3. Results and discussion3. Results and discussion

BHT

RB-2

RB-4

•抗氧化能力的高低与多酚化合物，黄酮，生育酚，生育三烯酚和谷维素的含量成正比。

•抗氧化能力的高低与多酚化合物，黄酮，生育酚，生育三烯酚和谷维素的含量成正比。

米糠中存在一定量的多酚化合物，黄酮，谷维素，生育酚和生育三烯酚，表现出不同程度的抗氧化能力。

3. Results and discussion3. Results and discussion

不同商业品种米糠中抗氧化物质的含量有很大差异，这可以作为食品加工中原料选择的依据。

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