Natural Medicines and Products Research Laboratory (NaturMeds), Institute of Bioscience, Universiti Putra Malaysia, Serdang 43400, Malaysia.
Molecules. 2021 Feb 19;26(4):1084. doi: 10.3390/molecules26041084.
Luteolin and apigenin derivatives present in oil palm () leaves (OPL) are reported to possess excellent antioxidant properties relating to numerous health benefits. To meet the global demand for flavonoids, OPL, which is plentifully generated as an agricultural by-product from oil palm plantations, can be further exploited as a new source of natural antioxidant compounds. However, to produce a standardized herbal preparation, validation of the quantification method for these compounds is required. Therefore, in this investigation, we developed and validated an improved and rapid analytical method, ultra-high-performance liquid chromatography equipped with ultraviolet/photodiode array (UHPLC-UV/PDA) for the quantification of 12 luteolin and apigenin derivatives, particularly focusing on flavonoid isomeric pairs: orientin/isoorientin and vitexin/isovitexin, present in various OPL extracts. Several validation parameters were assessed, resulting in the UHPLC-UV/PDA technique offering good specificity, linearity, accuracy, precision, and robustness, where the values were within acceptable limits. Subsequently, the validated method was employed to quantify luteolin and apigenin derivatives from OPL subjected to different drying treatments and extraction with various solvent systems, giving total luteolin (TLC) and apigenin content (TAC) in the range of 2.04-56.30 and 1.84-160.38 µg/mg extract, respectively. Additionally, partial least square (PLS) analysis disclosed the combination of freeze dry-aqueous methanol yielded OPL extracts with high TLC and TAC, which are strongly correlated with antioxidant activity. Therefore, we provide the first validation report of the UHPLC-UV/PDA method for quantification of luteolin and apigenin derivatives present in various OPL extracts, suggesting that this approach could be employed in standardized herbal preparations by adopting orientin, isoorientin, vitexin, and isovitexin as chemical markers.
油棕（）叶中存在的木犀草素和芹菜素衍生物据报道具有优异的抗氧化性能，与许多健康益处有关。为了满足全球对类黄酮的需求，可以进一步利用作为油棕种植园农业副产物大量产生的油棕叶作为天然抗氧化化合物的新来源。然而，为了生产标准化的草药制剂，需要验证这些化合物的定量方法。因此，在这项研究中，我们开发并验证了一种改进的快速分析方法，即超高效液相色谱法（UHPLC）与紫外/光电二极管阵列（UV/PDA）联用，用于定量测定 12 种木樨草素和芹菜素衍生物，特别是关注各种油棕叶提取物中存在的黄酮类异构体对：荭草苷/异荭草苷和牡荆苷/异牡荆苷。评估了几个验证参数，结果表明 UHPLC-UV/PDA 技术具有良好的特异性、线性、准确性、精密度和稳健性，其值在可接受的范围内。随后，使用验证的方法来定量不同干燥处理和不同溶剂系统提取的油棕叶中的木樨草素和芹菜素衍生物，得到总木樨草素（TLC）和芹菜素含量（TAC）分别在 2.04-56.30 和 1.84-160.38 µg/mg 提取物范围内。此外，偏最小二乘（PLS）分析揭示了冷冻干燥-水甲醇的组合产生了 TLC 和 TAC 高的油棕叶提取物，它们与抗氧化活性密切相关。因此，我们提供了 UHPLC-UV/PDA 方法用于定量测定各种油棕叶提取物中木樨草素和芹菜素衍生物的首次验证报告，表明该方法可以通过采用荭草苷、异荭草苷、牡荆苷和异牡荆苷作为化学标志物用于标准化草药制剂。
