落叶松多聚原花青素催化氢解产物抗氧化活性研究

Study on the Antioxidant Activity of Catalytic Hydrogenolysis Products of Polymeric Proanthocyanidins from Larix gmelini Bark

以落叶松(Larix gmelini)树皮中提取的多聚原花青素(LPPC)为原料,通过Pd/C催化氢解反应制备了低聚原花青素(LHOPC),同时利用电子自旋共振和自旋捕集技术,研究了催化氢解产物对3种氧自由基的清除能力。结果表明:催化氢解反应得到的低聚原花青素具有较强的清除自由基的能力。在实验条件下,LHOPC清除3种氧自由基的IC50分别为8.06 mg/ml(羟基自由基),0.048 mg/ml(超氧自由基)和0.19 mg/ml(脂类自由基),均明显低于从落叶松树皮直接提取得到的低聚及多聚原花青素,略高于葡萄籽低聚原花青素。HPLC分析和圆二色谱的分析结果表明,儿茶素等小分子产物含量的提高和反应过程中产物构型的改变是催化氢解反应提高产物清除自由基能力的主要原因。

Oligomeric proanthocyanidins were prepared from polymeric proanthocyanidins of Larix gmelini by Pd/C catalytic hydrogenolysis. With ESR （electron spin resonance） and spin trapping techniques, the scavenging effects of the hydrogenolysis products against three kinds of oxygen free radical were investigated. The results showed that the oligomeric proanthocyanidins exhibit a strong antioxidant activity, and its IC50 to hydroxyl, superoxide and lipid free radicals are 8.06 mg/ml, 0.048 mg/ml and 0.19 mg/ml, respectively. All these data were obvious lower than those of oligomeric and polymeric proanthocyanidins extracted from Larix gmelini, but a little higher than those of oligomeric proanthocyanidins extracted from grape seeds. HPLC results and Circular Dichroism spectra revealed that the increase of catechin content and the change of steric structure of products during the reaction are the main reasons responsible for the enhancement in antioxidant activity of catalytic hydrogenolysis products.