Department of Plant and Soil Sciences, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa.
Africa Institute of South Africa (AISA), Human Sciences Research Council (HSRC), Pretoria 0002, South Africa.
Molecules. 2021 Apr 15;26(8):2298. doi: 10.3390/molecules26082298.
Lam. is one of the world's most useful medicinal plants. Different parts of the tree contain a rich profile of important minerals, proteins, vitamins, and various important bioactive compounds. However, there are differences in the phytochemical composition of the medicinal plant's raw materials due to seasonal variation, cultivation practices, and post-harvest processing. The main objective of this study was therefore to determine the effect of harvesting frequencies on selected bioactive compounds of a cultivar (PKM1) grown in a hydroponic system under a shade net structure. Three harvesting frequency treatments were applied in the study, with the plants harvested at every 30 days (high frequency), 60 days (intermediate frequency), and 90 days (low frequency) respectively. H-NMR was used for data acquisition, and multivariate data analysis by means of principal component analysis (PCA), partial least square discriminatory analysis (PLS-DA), and orthogonal partial least square discriminatory analysis (OPLS-DA) were applied to determine the changes in the leaf metabolite profile, and also to identify the spectral features contributing to the separation of samples. Targeted metabolite analysis was used to match the NMR peaks of the compounds with the NMR chemical shifts of the contribution plot. The contribution plot showed that the increase in concentration of some compounds in aliphatic, sugar and aromatic regions contributed to the separation of the samples. The results revealed that intermediate and low harvesting frequencies resulted in a change in the leaf metabolite profile. Compounds such as chlorogenic acid, ferulic acid, vanillic acid, wogonin, esculetin, niazirin, and gamma-aminobutyric acid (GABA) showed an increase under intermediate and low harvesting frequencies. These results provide insight into the effect of harvesting frequencies on the metabolite profile and associated medicinal activity of .
蓝桉是世界上最有用的药用植物之一。树的不同部位含有丰富的重要矿物质、蛋白质、维生素和各种重要的生物活性化合物。然而，由于季节性变化、种植实践和收获后加工，药用植物原料的植物化学成分存在差异。因此，本研究的主要目的是确定在遮荫网结构下的水培系统中种植的一个品种（PKM1）的收获频率对选定生物活性化合物的影响。本研究应用了三种收获频率处理，分别为每 30 天（高频率）、60 天（中频率）和 90 天（低频率）收获一次。采用 H-NMR 进行数据采集，并应用主成分分析（PCA）、偏最小二乘判别分析（PLS-DA）和正交偏最小二乘判别分析（OPLS-DA）等多元数据分析方法，确定叶片代谢物谱的变化，并确定导致样品分离的光谱特征。靶向代谢物分析用于将化合物的 NMR 峰与贡献图的 NMR 化学位移进行匹配。贡献图显示，脂肪族、糖和芳族区域中一些化合物浓度的增加有助于样品的分离。结果表明，中低收获频率会导致叶片代谢物谱发生变化。在中低收获频率下，绿原酸、阿魏酸、香草酸、汉黄芩素、花椒素、尼扎林和γ-氨基丁酸（GABA）等化合物的浓度增加。这些结果深入了解了收获频率对蓝桉代谢物谱和相关药用活性的影响。
