Braünlich Paula Marie, Inngjerdingen Kari Tvete, Inngjerdingen Marit, Johnson Quinton, Paulsen Berit Smestad, Mabusela Wilfred
School of Pharmacy, University of Oslo, Norway.
Oslo University Hospital, Oslo, Norway.
Fitoterapia. 2018 Jan;124:182-187. doi: 10.1016/j.fitote.2017.11.016. Epub 2017 Nov 15.
Artemisia afra (Jacq. Ex. Willd), is an indigenous plant in South Africa and other parts of the African continent, where it is used as traditional medicine mostly for respiratory conditions. The objective of this study was to investigate the structural features of the polysaccharides from the leaves of this plant, as well as the biological activities of the polysaccharide fractions against the complement assay. Leaves of Artemisia afra were extracted sequentially with organic solvents (dichloromethane and methanol), 50% aqueous ethanol, and water at 50 and 100°C respectively. The polysaccharide extracts were fractionated by ion exchange chromatography and the resulting fractions were tested for biological activity against the complement fixation assay. Active fractions were further fractionated using gel filtration. Monosaccharide compositions and linkage analyses were determined for the relevant fractions. Polysaccharides were shown to be of the pectin type, and largely contain arabinogalactan, rhamnogalacturonan and homogalacturonan structural features. The presence of arabinogalactan type II features as suggested by methylation analysis was further confirmed by the ready precipitation of the relevant polysaccharides with the Yariv reagent. An unusual feature of some of these polysaccharides was the presence of relatively high levels of xylose as one of its monosaccharide constituents. Purified polysaccharide fractions were shown to possess higher biological activity than the selected standard in the complement assay. Digestion of these polysaccharides with an endo-polygalacturonase enzyme resulted in polymers with lower molecular weights as expected, but still with biological activity which exceeded that of the standard. Thus on the basis of these studies it may be suggested that immunomodulating properties probably contribute significantly to the health-promoting effects of this medicinal plant.
南非艾草（Artemisia afra (Jacq. Ex. Willd)）是南非及非洲大陆其他地区的本土植物，在当地主要被用作治疗呼吸道疾病的传统药物。本研究的目的是调查该植物叶片中多糖的结构特征，以及多糖组分在补体检测中的生物活性。分别用有机溶剂（二氯甲烷和甲醇）、50%乙醇水溶液以及50℃和100℃的水依次提取南非艾草的叶片。多糖提取物通过离子交换色谱进行分级分离，所得级分进行补体固定检测以测试其生物活性。活性级分再用凝胶过滤进一步分级分离。对相关级分进行单糖组成和连接分析。结果表明多糖为果胶类型，主要含有阿拉伯半乳聚糖、鼠李半乳糖醛酸聚糖和同型半乳糖醛酸聚糖的结构特征。甲基化分析表明存在II型阿拉伯半乳聚糖特征，相关多糖能与Yariv试剂快速沉淀进一步证实了这一点。这些多糖的一个不寻常特征是其单糖成分之一木糖的含量相对较高。在补体检测中，纯化的多糖级分显示出比所选标准品更高的生物活性。用内切多聚半乳糖醛酸酶消化这些多糖，得到了预期的分子量较低的聚合物，但仍具有超过标准品的生物活性。因此，基于这些研究可以认为，免疫调节特性可能对这种药用植物的健康促进作用有显著贡献。
