from Food Chemistry 111 (2008)

1. Antioxidant components and properties of five long-grained rice bran extractsfrom commercial available cultivars in Thailand 汇报人：胡冬梅 指导老师：薛照辉副教授 from Food Chemistry 111 (2008)

2. content 1 Introduction 2 Materials and methods 3 Results and discussion

3. 1. Introduction 1. Lower of blood cholesterol 2.Decrease atherosclerosis disease 3. Laxative effect 4. Anticancer 5. Restrain the melanin 6. Prevent urinary stones

4. rice bran 1. Introduction Ricebran powder has a high nutritive value sterols phenolic compounds higher alcohols tocotrienols tocopherols gamma-oryzanol

5. 2. Materials and methods Mill rice grain sieve to separate grain from rice bran 1 Rice branwas ground, then passed through sieves heated at100 ℃ for 15 min to inactivate endogenous lipase 2 RB-1 RB-2 RB-3 RB-4 RB-5 Rice bran powder (10.0 g) was extracted with methanol (150 ml)for 12 h in an electrical shaker at room temperature. 3 twice again 4 The extractwas filtered through filter paper and the solventwas removed. 5 The extracts were combined，then evaporate under vacuum using a rotary evaporator 6 Theresidual crude methanolic rice bran extract was weighed andstored at20℃ under a nitrogen gas stream

6. 2.1 Determination of TPC Rice bran extract was dissolved methanol. 1 Rice bran extract (250 µl)mixwith 500µl Folin–Ciocalteureagent and a further 6.0 ml of distilled water. 2 The mixture wasshaken vigorously and 2.0ml Na2CO3 (15%w/v) wereadded and the mixture was again shaken vigorously for 2 min. 3 Thefinal volume was10.0 ml with distilled water. The mixture was left to stand for 2 h at room temperature.The absorbance at 750 nmwas measured by using a UV–vis spectrophotometer 4

7. 2.2 Determination of TFC Rice bran extract was dissolved in methanol. 250µl+ distilled water 1.25 ml + 75 µl 5%NaNO2 room temperature for 6 min step 1 150µl of 10% AlCl3were added. This mixture stand for a further 5 min. 0.5 ml of 1 M NaOH was added. step 2 The solution was shaken vigorously. The absorbance at 510 nmwas measured with a UV–vis spectrophotometer step 3

8. 2.3 Determination of γ-oryzanol content mobile phase Rice bran extract100.0 mg was dissolved in 1.0 ml of methanol 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 filterthrough a syringe filter with PTFE(聚四氟乙烯) RP-HPLC

9. 2.4 Determination of total tocopherol, total tocotrienol, tocopheroland tocotrienol isomer contents Tocopherol isomer content of rice branextract was determinedby RP-HPLC Agilent 1100 seriesRP-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

10. scavenging ability(%) = [1-Absorbancesample/Absorbancecontrol]×100 2.5 Determination of DPPH radical-scavenging activity 0.5 mlsample solution in methanol was mixed with 2.5 ml 0.5 mMmethanolic solution of DPPH. The mixture was shaken vigorouslyand incubated for 30 min in the dark at room temperature. DPPH Theabsorbance was measured at 517 nm against a blank, using a UV–vis spectrophotometer

11. 2.6 Determination of reducing power Rice bran extract in methanol (2.5 ml) wasmixed 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. 1 2 3 4 The upper solution (5.0 ml)was mixed with distilled water (5.0 ml) and 1.0 ml ferric chloride (1.0%) was added Trichloroacetic acid (10%, 5.0 ml) was added to mixture, then centrifuged at 6000 g for 10 min The absorbance was measured at 700 nm BHT was used for comparison

12. 2.7 Determination of ferrousion-chelating activity The reaction mixture (2.0 ml) contained hexamine (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) Themixture was shaken vigorously and left to stand for 3 min at room temperature. Absorbance of the mixture was determined at485 nm against ablank.(Na2EDTA）was used for comparison.

13. % of inhibition of lipidperoxidation = [1-Absorbancesample/Absorbancecontrol]×100 2.8 Determination of lipid peroxidation inhibition 4.0 ml linoleic acid (10 mM) in Na3PO4 buffer (0.2 M) 2 Rice bran extract in methanol (200 µl) Stand in darkness at 37 ℃ for15 h 1 3 6 4 BHT was used for comparison 6.0 ml of 60% methanol were added 5 Absorbance measured at 234 nm against a blank

14. not significantlydifferent 3. Results and discussion ▲ ▼ ▼ ▲

15. 3. Results and discussion 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 Different forms of tocopherol exhibit different antioxidative effects T↑,δ˃γ˃β˃α a mixture of phytosteryl and campesterylferulates have antioxidant properties in many types of in vitro model systems

16. 3. Results and discussion BHT BHT˃RB-2˃RB-1˃RB-3˃RB-5˃RB-4 RB-3 ▲ RB-2 ▼ RB-4 RB-1 RB-5

17. 3. Results and discussion BHT˃RB-2˃RB-1˃RB-3˃RB-5˃RB-4

18. 3. Results and discussion EC50，半最大效应浓度 是指能引起50%最大效应的浓度。

19. 3. Results and discussion Na2EDTA RB-2 RB-1 RB-3 RB-5 RB-4

20. 3. Results and discussion BHT RB-2 RB-4

21. 3. Results and discussion 03 02 • 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。 01 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。 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。

22. Thank You!