黑米麸皮与紫包菜花青素提取物的组成、抗氧化性与稳定性比较研究

Comparative Studies on the Composition, Antioxidant Activity and Stability of Anthocyanins from Black Rice Bran and Purple Cabbage

利用液质联用(HPLC-MS)结合串联质谱(MS-MS)技术,分别测定黑米与紫包菜花青素提取物的组成,结果表明:黑米麸皮花青素提取物的主要成分为矢车菊色素-3-葡萄糖苷,几乎占总含量的95%以上;而在紫包菜中的花青素提取物中,检测到了24个花青素组分,主要为酰基化的矢车菊素。FRAP、DPPH及ORAC法的抗氧化活性测定结果显示:在FRAP法与DPPH法中,黑米麸皮花青素提取物抗氧化性高于紫包菜花青素提取物,符合花青素的构效关系;而ORAC法测定的结果则相反。两种花青素提取物在pH值分别为2.0、3.0和7.4时的稳定性比较显示:黑米麸皮花青素提取物的稳定性低于紫包菜花青素,pH值越大两者的稳定性差别也越大,这可能是ORAC法的结果呈现出与花青素构效关系相反结果的原因。

The composition of anthocyanins extracted from black rice bran and purple cabbage were analyzed by HPLC-MS combined with MS-MS. The results showed that cyanidine-3-glucoside was the major component in black rice bran, accounting for more than 95% of total anthocyanins. Twenty-four anthocyanins were identified from purple cabbage and acylated cyanidine was predominant among them. Anthocyanins extracted from black rice bran had higher ferric reducing antioxidant power （FRAP） and DPPH radical scavenging capacity that those extracted from purple cabbage. The results obtained for the FRAP and DPPH radical scavenging capacity of both extracts supported the structure-effect relationship. On the contrary, the oxygen radical absorption capacity （ORAC） of the extract from black rice bran was lower than that of the extract from purple cabbage. The black rice bran extract was less stable to pH 2.0, 3.0 and 7.4 than the purple cabbage extract. The higher the pH, the greater the stability difference between both extracts. Presumably because of this, the ORAC difference between them broke the structure-effect relationship of anthocyanins.