Scientists in China have unveiled a streamlined analytical strategy that could reshape how one of traditional Chinese medicine’s most important herbal drugs is tested for quality, combining three established laboratory techniques into a single, cost-effective workflow capable of measuring seven bioactive compounds at once. The study, published in BMC Complementary Medicine and Therapies, focuses on Rehmanniae Radix Praeparata, the processed root of Rehmannia glutinosa, a plant whose tuberous roots have been used for centuries in East Asian medical practice and which remains one of the most frequently prescribed botanical materials in modern Chinese pharmacopoeia formulations. The research addresses a long-standing bottleneck in herbal medicine quality control: the difficulty and expense of verifying that every batch of a processed botanical product contains the full complement of chemical constituents responsible for its biological activity.
The team, led by researchers from Pingxiang Health Vocational College in Jiangxi Province together with collaborators at the Institute of Chinese Materia Medica at Shanghai University of Traditional Chinese Medicine and the Shanghai R&D Center for Standardization of Chinese Medicines, set out to solve a problem familiar to anyone working in natural product analysis. Traditional quality assessment of herbal drugs typically requires reference standards for every compound to be quantified, and these purified chemical standards are often expensive, unstable, or simply unavailable. For a complex botanical like processed rehmannia root, which contains dozens of structurally related molecules, buying and maintaining a library of authentic standards for each analysis becomes prohibitively costly for routine batch testing. The researchers’ solution was to implement quantitative analysis of multi-components with a single marker, abbreviated QAMS, a technique that uses just one well-characterized compound as an internal reference and then calculates the concentrations of related compounds through mathematically derived conversion factors.
The chemistry at the heart of the study centers on phenylethanoid glycosides, a class of water-soluble phenolic compounds that the researchers identified as particularly suitable targets for quality assessment because of their relative stability during the processing steps that transform raw rehmannia root into the finished medicinal material. Processing, known in traditional practice as “pao zhi,” typically involves repeated steaming and drying cycles that dramatically alter the chemical profile of the raw root, converting some constituents into new compounds while degrading others. The fact that phenylethanoid glycosides survive this treatment comparatively intact makes them reliable chemical signatures of both the raw material’s identity and the processed product’s consistency. Among these compounds is acteoside, also known as verbascoside, a phenylethanoid glycoside that has attracted considerable scientific interest for its antioxidant and anti-inflammatory properties and which the team selected as the single reference marker for their quantitative method.
The analytical strategy unfolded in three integrated stages. First, the researchers used ultra-performance liquid chromatography coupled with electrospray ionization mass spectrometry, or UPLC-ESI-MS, to map the chemical constituents of processed rehmannia root, identifying eight major compounds. This mass spectrometric survey allowed the team to characterize the molecular inventory of the herb with high specificity, using the precise mass-to-charge ratios and fragmentation patterns of each molecule to confirm identities before any quantitative work began. Second, they developed and validated a UPLC method with photodiode array detection, UPLC-PDA, capable of separating and quantifying seven distinct phenylethanoid glycosides in a single chromatographic run. Third, they performed high-performance liquid chromatography fingerprinting, a technique that generates a characteristic chemical barcode of the entire sample, which they then applied across seventeen independent batches of processed rehmannia root to assess batch-to-batch consistency.
The centerpiece of the method is the set of relative correction factors, or RCFs, that link the detector response of each target compound to that of the acteoside reference. The researchers calculated these factors in two independent ways, one based on averaging measured response ratios and the other derived from linear regression of concentration against peak area, and then compared the results obtained through both approaches against the gold standard: the external standard method, in which every compound is quantified against its own dedicated reference material. The agreement between the single-marker calculations and the conventional external standard measurements was excellent, demonstrating that the QAMS approach can deliver accurate concentrations of seven compounds simultaneously while requiring only one expensive reference standard rather than seven. This validation against the established method is the crucial step that transforms the technique from a theoretical convenience into a laboratory-ready tool.
The performance metrics reported for the validated method are impressive by any analytical standard. Linearity across the calibration range was exceptional, with correlation coefficients of at least 0.9994 for all seven compounds, indicating an almost perfectly proportional relationship between concentration and detector signal. Precision, accuracy, and stability tests all passed accepted validation criteria, and recovery experiments, in which known quantities of the analytes were spiked into samples to see how much could be recovered, yielded values between 98.62 percent and 102.64 percent. Recovery values this close to 100 percent, and this tightly clustered, indicate that the sample preparation and chromatographic separation introduce essentially no systematic bias, a level of analytical rigor that regulatory agencies demand before a method can be adopted for official quality control.
The fingerprinting analysis added a complementary dimension to the quantitative work. By comparing the full chromatographic profiles of seventeen batches of processed rehmannia root, the researchers calculated similarity coefficients ranging from 0.914 to 0.986, where a value of 1.0 would indicate two chemically identical samples. Similarity scores this high across independently produced batches demonstrate that commercial supplies of the herb are remarkably consistent, and it gives manufacturers and regulators a practical benchmark: any batch whose fingerprint falls below an agreed similarity threshold would be flagged for further investigation. Fingerprinting is particularly valuable because it does not merely measure the selected target compounds but reveals the presence or absence of the entire detectable chemical spectrum, catching adulteration, substitution, or processing errors that a targeted assay of seven compounds alone might miss.
The significance of this work extends well beyond a single herb. QAMS methodology has been gaining traction internationally as a pragmatic response to the reference-standard bottleneck in botanical and other complex-matrix analysis, and each successful demonstration strengthens the case for its broader adoption in pharmacopoeial standards. For processed rehmannia root specifically, the implications are immediate. The herb appears in numerous classical and modern formulations, and its processed form differs chemically and therapeutically from the raw root, yet comprehensive quality specifications for the processed material have lagged behind those for many other botanicals. A validated method that quantifies seven phenylethanoid glycosides simultaneously, verified by mass spectrometric identification of the underlying constituents and cross-checked by fingerprint similarity analysis, provides exactly the kind of multi-dimensional quality framework that modernization efforts in Chinese medicine have been calling for.
The researchers also emphasize the practical economics of the approach. Because only acteoside is needed as a reference standard, laboratories performing routine batch release testing can cut their standards budget substantially while simultaneously increasing the number of compounds they monitor, since the marginal cost of quantifying an additional compound via a relative correction factor is negligible once the factor has been established. This inversion of the usual trade-off, in which testing more compounds means spending more money, is the core appeal of QAMS for quality control laboratories, particularly in regions where access to expensive reference materials is limited. The authors conclude that the combined UPLC-PDA, QAMS, and fingerprint strategy offers a practical, reliable, and cost-effective route to quality evaluation of both raw Rehmanniae Radix and the processed Praeparata form, and the method’s reliance on widely available HPLC and UPLC instrumentation means it can be implemented without specialized equipment beyond what most established analytical laboratories already possess.
As herbal medicines continue to gain a foothold in global markets and integrate into mainstream healthcare systems, the scientific infrastructure supporting their quality assurance becomes ever more consequential. Studies like this one, published open access and validated with transparent performance data, represent the unglamorous but essential work of translating centuries of empirical botanical knowledge into the language of modern analytical chemistry. The convergence of mass spectrometric identification, single-marker quantification, and fingerprint-based consistency testing in a single coherent protocol for processed rehmannia root offers a template that researchers studying other botanical drugs are likely to emulate, and it moves the field one step closer to a future where every batch of a traditional herbal medicine can be verified with the same rigor, and at comparable cost, as any synthetic pharmaceutical.
Subject of Research: Quality evaluation of Rehmanniae Radix Praeparata (processed root of Rehmannia glutinosa) through quantification of seven phenylethanoid glycosides using a single-marker multi-component analysis method combined with UPLC-MS identification and HPLC fingerprinting
Subject of Research: Medicine
Article Title: Quantitative determination of seven phenylethanoid glycosides in Rehmanniae Radix Praeparata using a single-marker multi-component analysis method
Article References: Zou, X.-L., Deng, G., Wu, J.-H., Zhang, T., Wang, Y.-L., & Chou, G.-X. (2026). Quantitative determination of seven phenylethanoid glycosides in Rehmanniae Radix Praeparata using a single-marker multi-component analysis method. BMC Complementary Medicine and Therapies. https://doi.org/10.1186/s12906-026-05541-w
Image Credits: AI Generated
DOI: 10.1186/s12906-026-05541-w
Keywords: Rehmanniae Radix Praeparata, Phenylethanoid glycosides, Quantitative analysis of multi-components with a single marker, UPLC-DAD, UPLC-ESI-MS, HPLC fingerprint, Acteoside, Relative correction factors, Quality evaluation, Traditional Chinese medicine, Rehmannia glutinosa, Batch consistency
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Ophelia Keating. (September 11, 2026). Single-marker method quantifies seven glycosides in prepared Rehmannia root. Scienmag. https://scienmag.com/single-marker-method-quantifies-seven-glycosides-in-prepared-rehmannia-root/
Ophelia Keating. “Single-marker method quantifies seven glycosides in prepared Rehmannia root.” Scienmag, 11 September 2026, https://scienmag.com/single-marker-method-quantifies-seven-glycosides-in-prepared-rehmannia-root/. Accessed 11 September 2026.
Ophelia Keating. “Single-marker method quantifies seven glycosides in prepared Rehmannia root.” Scienmag. September 11, 2026. https://scienmag.com/single-marker-method-quantifies-seven-glycosides-in-prepared-rehmannia-root/
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