Establishment of UPLC fingerprint and quantitative analysis of four components in turmeric standard decoction
After thousands of years of medication practice, decoctions are still the main dosage form for clinical use of traditional Chinese medicine. With the development of society and the advancement of technology, decoctions have been given new “connotations”, and the “standard decoctions” of traditional Chinese medicine have also emerged. Chinese medicine standard decoction is a standard substance prepared by referring to the traditional Chinese medicine decoction method and adopting a standardized decoction mode. It can standardize the clinical use of Chinese medicine, standardize the use of new Chinese medicine decoction pieces such as Chinese medicine formula granules in clinical practice, and provide reference for the research and development of Chinese medicine formula granules, classic formula preparations, and other products.
Turmeric is the dried rhizome of Curcuma longa L., a plant in the ginger family. It has the effects of breaking blood, promoting qi circulation, and relieving pain. It is a commonly used traditional Chinese medicine in clinical practice. The main chemical components of turmeric are phenols and terpenoids. In addition, it also contains a small amount of alkaloids, flavonoids, sterols, which have antibacterial, anti-inflammatory, antioxidant, anti-tumor, anti diabetes, liver protection, blood lipids and other effects. At present, turmeric is mainly distributed in Sichuan, Yunnan, Shaanxi and other regions. Sichuan and Yunnan are the authentic and main production areas of turmeric, and the market supply is mainly cultivated. There are few wild resources, making it difficult to form a scale. At present, the quality evaluation of turmeric mainly focuses on the analysis and determination of curcumin components and volatile oils, with less research on other types of components.
With the development of modern analytical technology, significant progress has been made in the quality control of traditional Chinese medicine. The application of quality control modes such as fingerprint/characteristic spectrum, one measurement and multiple evaluations, multi-component quantification, and multi-component thin-layer identification has made the concept of “overall quality control” of traditional Chinese medicine increasingly clear. This study established a UPLC fingerprint of turmeric standard decoction combined with chemometric analysis to identify differential quality markers, and combined with multi-component quantitative analysis to provide reference for the identification and quality control of turmeric standard decoction and related preparations.

Selection of measurement indicators. Curcumin and volatile oil are one of the main active components of turmeric, but their water solubility is relatively low. Standard decoctions use water as a solvent, and water-soluble components should be an important material basis for the effectiveness of decoctions. Therefore, in the study of quality standards for standard decoctions, in addition to measuring turmeric components, the determination of ferulic acid was also added. Compared with curcumin components, ferulic acid has relatively good water solubility and is a precursor for the synthesis of curcumin components. At the same time, during the decoction process of standard decoctions, curcumin components can also be converted into ferulic acid. Modern pharmacological research has confirmed that ferulic acid has antibacterial, antiviral, antioxidant, antithrombotic, lipid-lowering, reducing myocardial ischemia and oxygen consumption effects, and its medicinal value is becoming increasingly important. Attention is paid to the amount of ferulic acid in the standard decoction, Reflects the changes in the chemical composition of turmeric during the standard decoction process. The optimization of production processes for modern traditional Chinese medicine formulations such as granules based on “standard decoctions” has strong guiding significance.

Establishment of analytical methods. The polarity of chemical components in turmeric standard decoction varies greatly, including active ingredients such as curcumin with high lipid solubility and water-soluble ingredients such as ferulic acid. Therefore, the establishment of fingerprint spectrum requires the maximum extraction of the above components, while also considering the good chromatographic separation of chemical components with different polarities, and establishing a multi-component quantitative method consistent with the fingerprint spectrum conditions. Therefore, we conducted a systematic investigation of the mobile phase system, detection wavelength, and preparation method of the test solution to determine the optimal chromatographic conditions and preparation method of the test solution.
Evaluation of fingerprint spectra and content determination results. The similarity between the fingerprint spectra of 16 batches of turmeric standard decoction and the control fingerprint spectra is above 0.95, indicating that the overall similarity of the fingerprint spectra is high and can be used for the identification and quality control of turmeric standard decoction. Similarity calculation can reflect the stable composition and characteristic ratios of fingerprint peaks, but it cannot fully describe and distinguish the distribution patterns and interaction relationships of complex components contained in the fingerprint spectrum. Therefore, pattern recognition methods in chemometrics were used to study the fingerprint spectrum. The results showed that 16 batches of turmeric standard decoction samples had certain productivity, with 10 common peak areas as variables, HCA and PCA both classified 16 batches of samples into two categories, with samples from Sichuan production area classified into one category and samples from Yunnan production area classified into another category. A total of 6 differential biomarkers were found, namely peak, peak (ferulic acid), peak 8 (bis (demethoxycurcumin)), peak 9 (demethoxycurcumin), peak 2 (vanillin), and peak 1 (p-hydroxybenzaldehyde). Peak 5 was identified by high-resolution mass spectrometry, and it is speculated that it may be 1- (4-hydroxy-3,5-dimethoxyphenyl) -7- (4-hydroxy-3-methoxyphenyl) -1,4,6-heptadiene-3-one. Currently, there is a lack of reference standards and further research and confirmation are needed. By measuring the contents of ferulic acid, demethoxycurcumin, demethoxycurcumin, and curcumin, the results showed that the standard decoction of curcumin, demethoxycurcumin, double demethoxycurcumin, and ferulic acid prepared from turmeric raw materials in Dali, Yunnan were higher than those in samples from Yibin and Leshan, Sichuan. This also provides a reference for the selection of raw materials for enterprise production.
At present, there are many studies on the fingerprint spectrum and content determination of turmeric, but they mainly focus on the characterization and determination of volatile oils and curcumin components, and there is insufficient research on components with relatively high water solubility. This study establishes the UPLC fingerprint spectrum of turmeric standard decoction and simultaneously determines four effective ingredients, providing important references for improving the quality standards of turmeric medicinal materials, as well as establishing product quality standards for turmeric traditional Chinese medicine formula granules and classic formula preparations. This method is easy to operate, stable and reliable, with good repeatability.