Che Zain Mohamad Shazeli, Yeoh Jen Xen, Lee Soo Yee, Afzan Adlin, Shaari Khozirah
Natural Medicines and Products Research Laboratory (NaturMeds), Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.
Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor, Malaysia.
Antioxidants (Basel). 2021 Nov 12;10(11):1802. doi: 10.3390/antiox10111802.
Huge quantities of oil palm ( Jacq.) leaves (OPL) are generated as agricultural biomass from oil palm plantations. OPL are known to contain significant amounts of flavonoids. For maximal exploitation of these valuable antioxidant compounds, an innovative and sustainable extraction method employing natural deep eutectic solvents (NaDES) combined with ultrasonic assisted extraction was developed. Various NaDES composed of choline chloride as the hydrogen bond donor (HBD) and 1,2 propanediol (PD), 1,4 butanediol (BD), glycerol (GLY), glucose (GLU), maltose (MAL), and lactic acid (LA) as the hydrogen bond acceptor (HBA) were synthesized. The influence of these compositions, the methods of their synthesis, molar ratios, and water contents on their capacity to extract flavonoids from OPL was evaluated. Based on the results, it was found that methods which incorporate a heating step produced NaDES with the best capacity to extract OPL flavonoids. These thermal methods combined with molar ratios of 1:3 or 1:4 and water contents of 17 to 50% were found to be the optimal conditions for preparing NaDES, specifically when applied to the PD, BD, and GLY NaDES. Subsequently, UHPLC-UV/PDA-MS/MS analysis revealed NaDES extracts recovered by macroporous adsorption resin XAD7HP were able to optimally extract at least twelve luteolin and apigenin derivatives in OPL NaDES extracts prepared from glycerol and 1,4-butanediol demonstrated better and comparable efficiency as aqueous methanol in extracting flavonoids from OPL. The in vitro studies of antioxidant and wound healing properties supported these findings by exhibiting good free radical scavenging, cell proliferation, and migration activities. Additionally, the NaDES extracts also showed non-cytotoxicity effects at 1000 µg/mL and below on 3T3 fibroblast cells. Results of the study showed that NaDES could be a promising eco-friendly green solvent to extract bioactive OPL flavonoids that have great potential for applications as wound healing agents.
油棕种植园产生了大量作为农业生物质的油棕（Jacq.）叶（OPL）。已知OPL含有大量黄酮类化合物。为了最大程度地利用这些有价值的抗氧化化合物，开发了一种采用天然深共熔溶剂（NaDES）结合超声辅助提取的创新且可持续的提取方法。合成了各种由氯化胆碱作为氢键供体（HBD）和1,2 - 丙二醇（PD）、1,4 - 丁二醇（BD）、甘油（GLY）、葡萄糖（GLU）、麦芽糖（MAL）和乳酸（LA）作为氢键受体（HBA）组成的NaDES。评估了这些组成、合成方法、摩尔比和含水量对其从OPL中提取黄酮类化合物能力的影响。基于结果发现，包含加热步骤的方法所制备的NaDES具有最佳的提取OPL黄酮类化合物的能力。这些热法结合1:3或1:4的摩尔比以及17%至50%的含水量被发现是制备NaDES的最佳条件，特别是应用于PD、BD和GLY NaDES时。随后，超高效液相色谱 - 紫外/光电二极管阵列 - 质谱/质谱分析表明，通过大孔吸附树脂XAD7HP回收的NaDES提取物能够从甘油和1,4 - 丁二醇制备的OPL NaDES提取物中最佳地提取至少十二种木犀草素和芹菜素衍生物，在从OPL中提取黄酮类化合物方面，其效率与甲醇水溶液相当且更好。抗氧化和伤口愈合特性的体外研究通过展现出良好的自由基清除、细胞增殖和迁移活性支持了这些发现。此外，NaDES提取物在1000μg/mL及以下浓度时对3T3成纤维细胞也显示出无细胞毒性作用。研究结果表明，NaDES可能是一种有前景的环保绿色溶剂，可用于提取具有作为伤口愈合剂巨大应用潜力的生物活性OPL黄酮类化合物。
