| Summary: | 碩士 === 國立臺灣大學 === 食品科技研究所 === 90 === It was suggested, from the formation mechanism of atherosclerosis, that high blood lipid and oxidation stress which causes the oxidation of low-density lipoprotein (LDL) play important roles in atherosclerosis. Therefore, preventing or delaying the onset of atherosclerosis could start from lowering blood lipid and reducing the oxidation stress. The black-colored foods are known in the Chinese tradition as foods that could enhance blood circulation and delay aging. Recent research showed that age delaying is some how related to free radical scavenging and trapping effects. The objectives of this investigation are: (1) To study the in vitro antioxidative effects of five black-colored foods including Jew’s ear, black bean, sesame, black date and black rice; (2) To find the crude extracts of these five black-colored foods with the best antioxidative effect and to determine the contents of their antioxidative compounds; (3) To study the antioxidative effects of their combinations.
First, the crude extracts were prepared by extracting the five black-colored foods with five solvents of different polarities at room temperature(R.T.) and the boiling point of each solvent(Δ). Then they were tested for the 2,2-diphenyl-1-picrylhydrazyl(DPPH) free radical scavenging effect. The crud extracts with better effect and their IC50 values were the ethanol(Δ) and water(R.T.) crude extracts of Jew’s ear(81.7 and 90.1 μg/mL), the water(Δ) and water(R.T.) crude extracts of black bean (150.4 and 157.6 μg/mL), the water(Δ) and ethanol(Δ) crude extracts of sesame (68.3 and 80.3 μg/mL), the n-hexane(R.T.), ethyl acetate(R.T.) and ethyl acetate(Δ) crude extracts of black date (44.8, 51.9 and 59.2 μg/mL), and the water(Δ) and ethanol(Δ) crude extracts of black rice (22.0 and 29.9 μg/mL).
With regard to Cu2＋-induced oxidation of human LDL assay in vitro, the crude extracts with good antioxidative effects were Jew’s ear ethanol(Δ) crude extract, black bean ethanol(Δ) crude extract, sesame ethanol(R.T.) crude extract, black date n-hexane(Δ) crude extract and black rice ethanol(Δ) crude extract. The IC50 values of the inhibitory effects toward LDL oxidation were in the order of black date n-hexane(Δ) crude extract (6.36±0.28 μg/mL)＜black rice ethanol(Δ) crude extract (17.58±0.10 μg/mL)＜sesame ethanol(R.T.) crude extract (27.70±3.25 μg/mL)＜Jew’s ear ethanol(Δ) crude extract (52.73±2.32 μg/mL)≒black bean ethanol(Δ) crude extract (55.02±1.62 μg/mL).
Black bean ethanol(Δ) and black date n-hexane(Δ) crude extract contained the most abundant amount of total tocopherol and were 17.79±0.07 and 17.23±1.26 mg/100 g, respectively. Black date n-hexane(Δ) crude extract showed the highest amount of β-carotene, 20.32±0.85 mg/100 g. Ascorbic acid was not detected in all of the five crude extracts. The contents of total polyphenols in the five crude extracts were in order of black rice ethanol(Δ), sesame ethanol(R.T.), black date n-hexane(Δ), Jew’s ear ethanol(Δ), and black bean ethanol(Δ) crude extract, and were 7346.5±265.8, 5431.6±105.2, 3458.8±357.3, 3011.1±182.7, and 1904.1±64.1 mg gallic acid equivalent/100 g sample, respectively. In addition, black rice ethanol(Δ) crude extract contained the highest amount of anthocynidins (1.94±0.03 mg/100 g). The browning index of sesame ethanol(R.T.) crude extract was the highest, and the value was 1.48±0.01.
Crude extracts were assigned with the following numbers: (1) Black date n-hexane(Δ) crude extract; (2) Black rice ethanol(Δ) crude extract; (3) Sesame ethanol(R.T.) crude extract; (4) Jew’s ear ethanol(Δ) crude extract; (5) Black bean ethanol(Δ) crude extract. Equal volumes of these extracts were mixed to 26 combinations(A~Z form) at the concentrations of their IC50. The results showed that the best inhibitory effect were C(1＋4)( 76.9±2.7﹪), N(1＋3＋4)( 73.0±7.4﹪), and Q(2＋3＋4)( 69.2±6.1﹪)forms, and the differences between the predicted and the experimental values were significantly different, which meant that these three combinations had synergistic effect. The combinations of F(2＋4), G(2＋5), M(1＋2＋5), and S(2＋4＋5) showed a slight antagonism.
|
|---|
