Methanol-soluble, β-elimination Products from Preparations of Alginic Acid Hydroxamate Exhibited DPPH Scavenging and Angiotensin Converting Enzyme Inhibitory Activities

在製備褐藻酸羥肟酸過程中，因為β-移除反應而產生甲醇可溶小分子產物。利用BioSil-ODS高效液相層析管柱(10×250mm)以乙腈：0.05%三氟醋酸為10:90（體積比）進行分離，以波長235nm之吸光值進行檢測β-移除反應產物。收集的區分液分別檢測羥肟酸含量、清除DPPH自由基活性與抑制血管收縮素轉換嗨活性。較高羥肟酸含量的區分液則進一步以Sephadex G-15膠濾層析管柱進行分離。結果顯示，各區分的DPPH清除活性與抑制血管收縮素轉換酶活性與各區分液中羥肟酸含量重疊，但管柱出現拖尾的現象。此重疊區分液再以乙腈：水為95:5（體積比），在矽膠薄層層析板進行展開分離。結果顯示，因為β-移除反應而產生小分子產物具有DPPH清除活性。
The methanol-soluble sugar hydroxamic acid derivatives obtained during the preparation of alginic acid hydroxamates (AAH) were separated by BioSil-ODS HPLC column (10×250 mm) in acetonitrite: 0.05% trifluoroacetic acid, 10:90 (V/V). The absorbance at 235 nm was set for monitoring β-elimination products. Each fraction was collected and assayed for hydroxamic acid contents, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, and inhibitory activity against angiotensin converting enzyme (ACE). The fraction with higher hydroxamic acid content was further separated by Sephadex G-15 column. Fractions containing both ACE inhibitory activity and DPPH scavenging activity overlapped with fractions containing high levels of hydroxamic acid derivatives. The chromatogram showed little tailing when judged by hydroxamic-acid content but significant tailing when judged by biological activity. Each fraction from above was further separated by silica-TLC in acetonitrite: distilled water, 95:5 (V/V). It was found that a methanol soluble fraction prepared from alginic acid hydroxamates (AAH) exhibited DPPH scavenging activity.