MARE-Marine and Environmental Sciences Centre, Polytechnic of Leiria, Cetemares, 2520-620 Peniche, Portugal.
Associate Laboratory i4HB-Institute for Health and Bioeconomy, School of Science and Technology, NOVA University Lisbon, 2819-516 Caparica, Portugal.
Molecules. 2021 Jul 15;26(14):4287. doi: 10.3390/molecules26144287.
that was collected in the four seasons was submitted to an extraction with ethanol:water (crude extracts Et80), followed by a liquid-liquid fractionation with organic solvents (fraction He from n-hexane; aqueous fractions AQ1, AQ2, AQ3 and AQ4; ethyl acetate fraction EA), with the aim of obtaining phlorotannin-enriched extracts. All the extracts (Et80, He, AQ1, AQ2, AQ3, AQ4 and EA) that were obtained for the of the four seasons were evaluated for their antioxidant capacity and total phenolic compounds. The summer extracts presented the highest contents in polyphenols (TPC), as well as the highest ferric reducing antioxidant power (FRAP), when compared to the samples from the other seasons. The reductive percentage of the DPPH (2,2-diphenyl-1-picryl-hydrazyl-hydrate) compound was similar between the seasons. For all the seasons, the EA extract showed the highest polyphenol content (TPC), and the highest antioxidant capacity (highest ferric reducing power (FRAP) and lowest concentration needed to reduce 50% of the DPPH compound), which is in agreement with a phlorotannin-enriched fraction. This study revealed that the polyphenol content and antioxidant power of the extracts are influenced by the time of harvest, as well as by the solvents used for their extraction.
在四个季节中收集的样品都用乙醇-水（粗提取物 Et80）进行提取，然后用有机溶剂进行液-液分馏（正己烷中的馏分 He；水相馏分 AQ1、AQ2、AQ3 和 AQ4；乙酸乙酯馏分 EA），以获得富含岩藻黄质的提取物。对四个季节的所有提取物（Et80、He、AQ1、AQ2、AQ3、AQ4 和 EA）进行了抗氧化能力和总酚含量的评估。与其他季节的样品相比，夏季提取物的多酚（TPC）含量最高，铁还原抗氧化能力（FRAP）也最高。DPPH（2,2-二苯基-1-苦基肼水合物）化合物的还原率在各季节之间相似。对于所有季节，EA 提取物的多酚含量（TPC）最高，抗氧化能力最强（铁还原能力最强（FRAP）和降低 DPPH 化合物 50%所需的最低浓度），这与富含岩藻黄质的馏分一致。这项研究表明，多酚含量和抗氧化能力的提取物受收获时间以及用于提取的溶剂的影响。
