毛杨梅树皮提取物抗氧化及清除自由基活性初步研究

Preliminary Study on Antioxidative and Radical-scavenging Activities of Extracts from Myrica esculenta Buch.-Ham.Bark

毛杨梅树皮提取物中的主要成分为局部梧酰化的聚原翠雀定，具有比原花青定抗氧化活性更强的化学结构特征。本研究以水为提取剂，通过强化提取、絮凝沉降、溶剂萃取、吸附分离等手段从树皮中提取分离得到产物，并经花色素反应定性和IR谱图鉴别。用凝胶渗透色谱法（GPC）和蒸汽渗透压法（VPO）测定产物的相对分子质量（Mr）及其分布，产物中95％以上组分的数均相对分子质量（Mn）为1705（相当于聚合度4-5），其余组分的Mn为798。用化学法测定目标产物分子中C-3的掊酰化度为38％。生物活性功能测定结果表明，目标产物能明显抑制油脂过氧化；络合Fe^2＋金属离子能力为181mg／g；1mg目标产物对1，1-二苯基-2-苦基肼（DPPH）自由基的清除速率为0．23mg／min，清除率为92％（试验浓度：产物与DPPH质量比为1：1．8），强于马尾松树皮原花色素试样。初步研究结果表明，毛杨梅树皮提取物可望进一步开发成为新型天然抗氧化及自由基清除荆。

Myrica esculenta Buch. -Ham. is a species of perennial tree distributing widely in Southern China. Major components of extracts from M. esculenta bark are partially galloylated polymeric prodelphinidins. Based on the feature of chemical structure, anti-oxidation activities of prodelphinidins are stronger compared with procyanidins. Extracts from the bark were obtained by intensified extraction with water followed by separation and purification. The extracts are proanthocyanidins identified by anthocy- anidin reaction and IR-spectra. Number-average molecular weight （Mn ） of the extracts are respectively 1705 （95 % ） and 798 （5 % ） determined by GPC and VPO. Galloylation degree at C-3 of the molecule were determined as 38 %. Bio-activity deter- mination showed that the extracts could evidently inhibit lipid peroxidation, complex metal ions （e. g. , Fe^2＋ , 181 mg/g） and scavenge free radical （ e. g. , DPPH, scavenging speed 0.23 mg/min for 1 mg target extracts ; scavenging rate 92 %, while mass ratio of extract to DPPH 1：1.8 ）. Results indicated that the extracts would be hopefully developed as a new type of natural antioxidant and radical-scavenging agent.