Study On Qualitative And Quantitative Analysis And Antioxidant Activity Of Anthocyanins From Six Purple Vegetables

Anthocyanins are a kind of natural water soluble pigment, which are mainly distributed in cell sap of roots, stems, leaves, flowers and fruits and are responsible for their bright colors such as red, blue and purple. Anthocyanins are foliage polyphenol compounds, which are glycosides of polyhydroxy and polymethoxy derivatives of 2-phenylbenzopyrylium or flavylium salts. Anthocyanins exhibit important bioactive functions, which have various health functions to human body, and can be a good source of natural pigment, so they can be used in food, pharmacy and cosmetics and used world-wildly because of their safety, nutrition and potential functionalities. In recent years, the studies about anthocyanins have been a researched hot spot at home and abroad. Researches on anthocyanins have increased rapidly in recent years, which have very important development values and wide application prospects. This paper introduced a systemic study on pretreatment, qualitative, quantitative and antioxidant activity screening methods of the anthocyanins, based on the six purple vegetables material, such as red onion, red cabbage, collard, purple yam, purple potato and purple sweet potato, to provide methodological and technical supporting for its development and utilization.(1) Pretreatment method of anthocyanins from vegetables analysisThis experiment used ultrasonic assistant method to extract anthcyanins from vegetables, and optimized the extraction solvent and the acidity of the solution, respectively. The result indicated that the anthcyanins from vegetables were the best extracted with 0.2% HCl (v/v) methanol solution by ultrasonic assistant method. The crude anthocyanins extracts which used into rapid analysis were first extracted by petroleum to remove possibly included fat-soluble components, then extracted by ethyl acetate to remove included flavonoids. The crude anthocyanins extracts which used into preparative separation were purified by macroporous adsorption resin, and compared the absorption with three kinds of resin such as D101, AB-8, and XAD-7. Macroporous resin XAD-7 was selected for purification of the crude anthocyanins extracts from vegetables, and static absorption and desorption experiments were performed to optimize the conditions.(2) Qualitative and quantitative analysis of anthocyanins from vegetables The qualitative analysis of anthocyanin compositions in six purple vegetables were determined using high performance liquid chromatography (HPLC) equipped with a diode array detector (DAD) and characterized by UV-visible spectra and electrospray ionization tandem mass spectrometry (ESI-MS2). The anthocyanin compositions in six purple vegetables were identified by combined application of UV-visible spectral and mass spetrometric analysis. Based on the MS and MS/MS spectra together with extracted molecular weights obtained, 6, 16, 17, 8, 6 and 11 kinds of anthocyanins were identified from red onion, red cabbage, collard, purple yam, purple potato and purple sweet potato by attentive studying on the mass spectra of compounds, comparing with reference data and combined application of UV-visible spectral information, respectively. The content of total anthocyanins from six purple vegetables was separately determined by dual-wavelength pH-differential method, and the RSD values of result were all under 3.0% (n=3). The anthocyanins in red onion were separated by high-speed counter-current chromatography (HSCCC), and Cyanidin 3-O-glucoside was obtained, the purity of which was more than 95%. Depending on the reference substance, the quantitative analysis method of cyanidin 3-O-glucoside in red onion was established.(3) The screening of antioxidant activity components for anthocyanins from vegetables This thesis discussed the antioxidant activity of of anthocyanins from six purple vegetables by the free radical DPPH elimination ability. The result indicated that the anthcyanins from the six purple vegetables had good activity of free radical DPPH elimination, and as increasing the concentration, the antioxidative activity being stronger. The screening method of antioxidant components for anthocyanins from vegetables was established, the proportional rate of free radical DPPH elimination of the extract of anthocyanins determined using area normalization method by HPLC at 520 nm, the hypothesis is that upon reaction with 1, 1-diphenyl-2-picrylhydrazyl (DPPH). The peak areas (A) of anthocyanins compounds with potential antioxidant effects in the HPLC chromatograms will be significantly reduced or disappeared, thus realizing rapid screening to the antioxidant anthocyanin compositions in the vegetables.