Extraction 、purification And Antioxidant Activity In Vitro Of Anthocyanins Pigment From Vigna Angularis(willd.) Ohwi Et Ohashi Hulls

As a natural antioxidant, Anthocyanin pigments has attracted widespread attention all-over the world. Vigna angularis(Willd.) Ohwi et Ohashi is a kind of black material, and it contains the natural touchable melanin, which has the function of anti-aging and improving one’s looks. As the main ingredient of melanin,anthocyanins can remove reactive oxygen species of body. The article is in-depth study on anthocyanins pigment from Vigna angularis(Willd.) Ohwi et Ohashi hulls,after extraction and purification, its stability and antioxidant activity in vitro was studied. The results showed that:1. Solvent extraction method, the optimal extraction conditions for anthocyanins from Vigna angularis(Willd.) Ohwi et Ohashi hulls was 60% ethanol concentration, solid-liquid ratio1:20, temperature 40℃, pH 2.0. Under the extraction conditions, the largest extraction amount for anthocyanins was 5.912 mg/g;Ultrasonic-assisted extraction, solid-liquid ratio was 1:20,time 30 minutes, power 320 W, temperature 45 ℃,the largest extraction amount for anthocyanins was 5.927mg/g;it is visible that ultrasonic-assisted extraction was better than solvent extraction, and the extraction time is short.2. Anthocyanin crude extracts obtained after the above extraction, contained lots of proteins, polysaccharides and other impurities, it is necessary for anthocyanin crude extracts to purify. Anthocyanin purified by using NKA-Ⅱ, AB-8, HPD100 C,HPD826, HPD400 five kinds of macroporous resin, the results showed that polar NKA-Ⅱ resin was best on purification of anthocyanins from Vigna angularis(Willd.)Ohwi et Ohashi Hulls. Static adsorption and desorption conditions were: anthocyanin concentration of Vigna angularis(Willd.) Ohwi et Ohashi Hulls was 0.4mg/mL, the optimal pH of anthocyanin solution was 2.0, the best desorption solution of NKA-Ⅱresin was 60% ethanol; dynamic adsorption and desorption conditions were: the best sample flow rate was 1.0 mL/min, the eluting effect of 80 mL 60% aqueous ethanol was best to NKA-Ⅱ resin. Anthocyanins purity was up to 3.06% before purification,but its purity was 37.8% after purification.3. Antioxidant activity of anthocyanins pigment from Vigna angularis(Willd.)Ohwi et Ohashi hulls was studied, the results showed that anthocyanins pigment from Vigna angularis(Willd.) Ohwi et Ohashi hulls had total antioxidant capacity and a strong superoxide anions, hydroxyl and DPPH radical scavenging ability. An half-inhibitory concentration IC50 of crude extracts were 0.24 mg/m L, 0.59 mg/m L and 0.21 mg/mL on superoxide anions, hydroxyl and DPPH radical, IC50 of purified anthocyanins were 0.22 mg/m L, 0.18 mg/m L and 0.12 mg/mL, while IC50 of Vc were0.21 mg/mL, 0.20 mg/mL and 0.11 mg/mL.The radical scavenging ability of crude extract from Vigna angularis(Willd.) Ohwi et Ohashi hulls were lower than Vc.The free radical scavenging of purified anthocyanins and Vc was comparable, even more than Vc. It is visible that antioxidant activity of purified anthocyanins pigment from Vigna angularis(Willd.) Ohwi et Ohashi hulls was better.4. The stability of anthocyanins pigment from Vigna angularis(Willd.) Ohwi et Ohashi hulls was studied in-depth, the results showed that anthocyanins pigment from Vigna angularis(Willd.) Ohwi et Ohashi hulls was suitable in the dark conditions,temperature 40 ℃ and pH 2.0, which anthocyanins pigment from Vigna angularis(Willd.) Ohwi et Ohashi hulls was relatively stable in K+, Na+, Ca2+, Al3+ solution;While it was extremely unstable in Fe3+ solution; when it was stable in 0.01mol/L Cu2+ solution, it was unstable in 0.1mol/L; and with extended time, the stability of anthocyanins pigment was significant decline. Food additives had different effect on anthocyanins pigment from Vigna angularis(Willd.) Ohwi et Ohashi hulls, dibutyl hydroxy toluene and wherein sucrose increased the stability of anthocyanins and sodium benzoate decreased the stability of anthocyanins.To sum up, Vigna angularis(Willd.) Ohwi et Ohashi hulls can be utilized as a new type of anthocyanins resources, the article provides a theoretical basis for the subsequent industrial production.