Abstract

Phytochemical analyses of guava leaf extracts, commonly applied in traditional medicine, revealed the presence of several bioactive polyphenols. In this study, we optimized the enrichment of total polyphenol from Guava leaf ethanolic extract (GEE) using six macroporous adsorptive resins (MAR) including AB8, D101, X5, ADS17, S400, and AD7. Also investigated are the contributions of adsorption time, extract concentration, pH, elution time, and eluent ethanol concentrations on the polyphenol enrichment potential of MAR. The antioxidant and anti-hemolytic properties of the crude and polyphenol-rich extracts were determined. Our results indicate that treatment of GEE extract with AB8 MAR at a concentration of 15 mg GEE/g resin, adsorption time of 45 min, elution time of 40 min, and eluent ethanol concentration of 50% (v/v) improved the flavonoids and phenol concentration of GEE by 2 and 2.5 folds respectively. The DPPH radical scavenging, ferric reducing ability of the plasma (FRAP), anti-hemolytic and anti-peroxidation activity of the resultant polyphenol-rich extracts improved by 1.5, 1.6, 1.4, and 1.88 folds respectively, when compared to the crude extract. Our work shows that the MAR-assisted enrichment operation is a rapid, feasible, and economical strategy for enriching bioactive polyphenols from guava leaf extracts.

摘要

对传统医学中常用的番石榴叶提取物进行的植物化学分析表明，其中存在多种生物活性多酚。在本研究中，我们使用 AB8、D101、X5、ADS17、S400 和 AD7 等六种大孔吸附树脂 (MAR) 优化了番石榴叶乙醇提取物 (GEE) 中总多酚的富集。还研究了吸附时间、提取物浓度、pH、洗脱时间和洗脱液乙醇浓度对 MAR 多酚富集潜力的影响。测定了粗提取物和富含多酚的提取物的抗氧化和抗溶血特性。我们的结果表明，用浓度为 15 mg GEE/g 树脂、吸附时间为 45 分钟、洗脱时间为 40 分钟、洗脱液乙醇浓度为 50% (v/v) 的 AB8 MAR 处理 GEE 提取物可提高黄酮类化合物和GEE 的苯酚浓度分别提高了 2 倍和 2.5 倍。与粗提物相比，所得富含多酚的提取物的DPPH自由基清除能力、血浆铁还原能力（FRAP）、抗溶血和抗过氧化活性分别提高了1.5、1.6、1.4和1.88倍。我们的工作表明，MAR 辅助富集操作是一种快速、可行且经济的从番石榴叶提取物中富集生物活性多酚的策略。