Study Of Bioactive Substance In Black Rice

Black rice, an ancient and precious rice species, is named because of its black color. Unlike other species of rice, black rice is eaten in the form of brown rice, namely the rice only without the outside layer (the hull) of whole grain, which makes the least damage to the nutrition since most nutrients are reserved without further processing. In this work, the components and structures of black rice pigment and the analytical methods of some biological activity materials in black rice were studied. The thesis mainly includes the following three parts: 1.The analysis of components and structures of black rice pigment. 2. Determination of Myo-inositol and D-chiro-inositol in black rice bran by capillary electrophoresis with electrochemical detection (CE-ED). 3. Determination ofγ-aminobutyric acid in germinated black rice germ by CE-ED method.Firstly, black rice pigments is a natural anthocyanin pigments, which has strong antioxidant and free radical scavenging capacity. Liquid chromatography-mass spectrometry (LC-MS) and CE-ED method were applied to determine the components and structures of black rice pigment. The result showed that there were two major anthocyanins in black rice pigment: cyanidin-3-glucoside and peonidin-3-glucoside.Secondly, Inositol, another important active ingredient in black rice, is also known as hexahydroxycyclohexane that has nine different forms. The well-known and nutritionally active forms are myo-inositol (MI) and D-chiro-inositol (DCI). CE-ED was developed for simultaneous determination of myo-inositol and D-chiro-inositol in black rice bran. A 140μm diameter copper-disk electrode was used as working electrode, which exhibited good response for the two analytes in 50 mmol/L sodium hydroxide solution, The optimum conditions for determination was optimized with regard to the potential applied to the working electrode, concentration of the running buffer, separation voltage and injection time. The analytes were separated within 20 min.Finally, using o-phthaldehyde (OPA) as a pre-column derivative agent, the contents of leucine, valine andγ-aminobutyric acid in germinated black rice germ were determined by CE-ED method. A 300μm diameter carbon disk electrode was used as the working electrode and the 50 mmol/L borax solution (pH 8.2) was used as running buffer. The effects of working potential, injection time and separation voltage were investigated. Under the optimum condition, three analytes were base-line separated within 15 min. The result indicated that the contents of amino acids from germinated black rice were higher than those in ungerminated black rice.