蓝莓花青素的酰化及其抗氧化性评价

Acylation reaction of blueberry anthocyanins with gallic acid and evaluation of its antioxidant activities

以三乙酰没食子酰氯作为酰基化剂,对蓝莓花青素提取物进行酰基化反应,制得酰基化蓝莓花青素产物没食子酸酰化花青素(GAA)。薄层色谱追踪反应进程、毛细管法测定熔点保证酰化剂合成纯度。对原花青素提取物、酰化中间产物和酰化花青素进行了红外光谱扫描,对比三者谱图,证实了酰基化实验的成功,并利用HPLC测定了酰化度。分别通过DPPH法、邻苯三酚自氧化法、卵磷脂脂质体法测定了酰化花色苷对于清除自由基、清除超氧阴离子和抑制脂质体过氧化的能力,酰化花色苷对于以上3实验的IC50分别为26.8、17.5、171.7μg/mL;相比较,原蓝莓花青素为39.8、27.0、219.7μg/mL;抗坏血酸为45.1、51.2、1084.8μg/mL。实验表明没食子酸酰化花青素方法切实可行,产物没食子酸酰化花青素的抗氧化性得到提升。

Gallic acyl anthocyanin（GAA） was prepared by chemical acylation with blueberry anthocyanins and gallic acid,and triacetyl gallic acid chloride was synthetized as a relevant acylating agent. The reaction process was monitored by thin-layer chromatography,and purity of the product was determined by melting point measured with capillary tube method. The infrared spectra of GAA,triacetyl gallic acyl anthocyanins,and original anthocyanins were compared and the results proved synthesis successfully. Acylation degree was measured with HPLC. The antioxidant activity of GAA was tested through comparison with original blueberry anthocyanin extracts by using different techniques. The antiradical activity,reducing O2^-. activity,and inhibition toward lipid peroxidation of GAA were measured by using 1,1-diphenyl-2-picrylhydrazyl, pyrogallot autoxidation,and lecithin liposome method, respectively. The IC50 values of GAA for the aforementioned assays were 26.8 ,17.5,171.7μg/mL, respectively. The IC50 values of the original anthocyanin extracts were 39.8,27.0,219.7μg/mL, respectively. The IC50 values of ascorbic acid were 45.1,51.2,1084.8μg/mL, respectively. Results showed that the acylation method could increase the antioxidant activity of original anthocyanin extracts.