National Key Laboratory of Chinese Medicine Modernization, State Key Laboratory of Component-Based Chinese Medicine, Tianjin Key Laboratory of TCM Chemistry and Analysis, Tianjin University of Traditional Chinese Medicine, Tianjin 301617, China.
Haihe Laboratory of Modern Chinese Medicine, Tianjin 301617, China.
Molecules. 2024 Feb 3;29(3):705. doi: 10.3390/molecules29030705.
Radix Rehmanniae (RR), a famous traditional Chinese medicine (TCM) widely employed in nourishing and invigorating the kidney, has three common processing forms in clinical practice, including fresh Radix Rehmanniae (FRR), raw Radix Rehmanniae (RRR), and processed Radix Rehmanniae (PRR). However, until now, there has been less exploration of the dynamic variations in the characteristic constituents and degradation products of catalpol as a representative iridoid glycoside with the highest content in RR during the process from FRR to PRR. In this study, an ultra-performance liquid chromatography coupled with photodiode array detector (UPLC-PDA) method was successfully established for the simultaneous determination of ten characteristic components to explore their dynamic variations in different processed products of RR. Among them, iridoid glycosides, especially catalpol, exhibited a sharp decrease from RRR to PRR. Then, three degradation products of catalpol were detected under simulated processing conditions (100 °C, pH 4.8 acetate buffer solution), which were isolated and identified as jiofuraldehyde, cataldehyde, and norviburtinal, respectively. Cataldehyde was first reported as a new compound. Moreover, the specificity of norviburtinal in self-made PRR samples was discovered and validated, which was further confirmed by testing in commercially available PRR samples. In conclusion, our study revealed the decrease in iridoid glycosides and the production of new degradation substances during the process from FRR to PRR, which is critical for unveiling the processing mechanism of RR.
地黄（RR）是一种著名的中药，广泛用于补肾，在临床上有三种常见的炮制形式，包括鲜地黄（FRR）、生地黄（RRR）和熟地黄（PRR）。然而，到目前为止，对于作为 RR 中含量最高的代表性环烯醚萜苷类化合物梓醇在从 FRR 到 PRR 的炮制过程中的特征成分和降解产物的动态变化，研究还较少。在这项研究中，建立了一种超高效液相色谱-光电二极管阵列检测（UPLC-PDA）方法，用于同时测定十种特征成分，以探讨它们在 RR 不同炮制产品中的动态变化。其中，环烯醚萜苷类，特别是梓醇，从 RRR 到 PRR 急剧下降。然后，在模拟炮制条件（100°C、pH4.8 醋酸缓冲溶液）下检测到梓醇的三个降解产物，分别鉴定为梓醇甲醛、梓醇醛和去甲梓醇。梓醇醛是首次报道的一种新化合物。此外，还发现并验证了自制 PRR 样品中去甲梓醇的特异性，在市售的 PRR 样品中也得到了进一步的证实。总之，本研究揭示了从 FRR 到 PRR 的炮制过程中环烯醚萜苷类的减少和新降解物质的产生，这对于揭示 RR 的炮制机制至关重要。
