Here, we present a quality evaluation method based on a multiple light scattering technique to evaluate the quality of Indigo Naturalis.
Quality control of Chinese herbal medicine is a crucial component of Chinese herbal medicine research and development. Faced with the challenges of modernization and internationalization of Chinese herbal medicine, it is urgent to establish thorough and effective procedures for quality identification of Chinese herbal medicine, and there is an urgent need for new analytical and testing techniques that are efficient, accurate, and environmentally friendly.
Multiple light scattering is a cutting-edge and analytical method that can accurately and rapidly assess the quality of Chinese herbal medicine without altering the nature or state of the sample or using organic reagents. Indigo Naturalis is considered a good remedy for pediatric hyperthermia, psoriasis, leukemia, and ulcerative colitis. In this study, the process of addition of Indigo Naturalis powder in water was recorded precisely using a multiple light scattering instrument.
The qualitative and quantitative measurements of the instrument can be used to accurately capture the overall trajectory and sinking behavior of Indigo Naturalis powder into water and to establish a rapid evaluation method for the quality of Indigo Naturalis with the transmission and backscattering spectrograms of the sample as qualitative indicators and stability index as a quantitative indicator. The analytical technique based on multiple light scattering provides a fast, accurate, green, and environmentally friendly method for the quality evaluation of Indigo Naturalis and supports the development and transformation of high-quality Indigo Naturalis.
In traditional Chinese medicine, during the course of disease treatment, the clinical effectiveness of medications and the safety of the course of treatment are directly impacted by the quality of Chinese herbal medicine. Utilizing cutting-edge identification technology, one can assess the efficacy of Chinese herbal medicine and guarantee user safety. The Chinese herbal medicine water test method refers to immersing the herbs in water or solvent, then quickly and precisely determining the medicine's authenticity by observing the changes in color, size, and shape1.
It was originally a good choice for the identification of Chinese medicine. However, the disadvantage of the traditional water test method is that the accuracy and sensitivity of distinguishing the authenticity of Chinese medicine are low because of the subjectivity of observation by the naked eye2. One of the key medicinal materials used in the water test method is Indigo Naturalis, considered an effective remedy for pediatric hyperthermia, psoriasis, leukemia, and ulcerative colitis3. The genuine Indigo Naturalis floats on the surface of water, and the water does not turn dark blue after shaking. However, the fake Indigo Naturalis has particles that sink, and the water will turn dark blue after shaking4. Its principle is due to hydrophobic and easily floatable indigo, indirubin, and other organic components of high-quality Indigo Naturalis. On the contrary, due to low organic matter, a large amount of lime, and heavy texture, some particles doped with fake Indigo Naturalis will sink quickly5. However, this method is only a simple qualitative identification, and it limits the rapid identification of the authenticity of Chinese herbal medicine and fails to reveal the changes of Indigo Naturalis in water.
Multiple light scattering technology is a technology that can measure multi-angle light signal scanning based on a laser passing through the sample. The incident light will be scattered when it penetrates the sample or encounters particles. If the scattered light penetrates through the sample, a transmission light signal is formed; If the sample concentration is high, the light will be reflected by the particles, forming a backscattering light signal. The changes in light intensity reflect the changes in particle concentration and particle size in liquid preparation6. The multiple light scattering instruments can quickly and accurately analyze phenomena such as emulsification, flocculation, precipitation, and rupture of suspension, emulsion, and foam liquid by multiple light scattering technology, as well as quantitatively analyze characteristics such as the rate of occurrence of the above phenomena.
Multiple light scattering technology has demonstrated significant benefits in particle stability monitoring7, red wine clarification8, and milk fermentation quality control9. Using this technology, the traditional water test method of Indigo Naturalis may be intuitive, quantitative, and scientific. Therefore, based on the principle of multiple light scattering technology, this study established a rapid evaluation method for the quality of Indigo Naturalis, taking the Turbiscan stability index (TSI) of the sample as the index of quality control (Figure 1).
According to traditional Chinese medicine, Indigo Naturalis has the power to clear heat and detoxification, cool blood, eliminate spots, purge fire, and arrest convulsion. Based on randomized double-blind controlled clinical trials11,12,13, Indigo Naturalis is effective in the treatment of psoriasis, ulcerative colitis, and acute promyelocytic leukemia in addition to its traditional treatment of cough and phlegm, hemorrhagic sym…
The authors have nothing to disclose.
The work wishes to acknowledge support from the National Natural Science Foundation of China (No. 82173976), National Key Research and Development Program (No. 2018YFC1707205), and State Key Laboratory of Innovative Drugs and High Energy Saving Pharmaceutical Equipment, Jiangxi University of Traditional Chinese Medicine (No. GZSYS202003).
Analytical balance (1/10,000) | Sartorious, Germany | BSA224S | www.sartorius.com.cn |
Funnel | Chengdu Kelong Chemical Co. LTD | Diameter 5 cm | www.cdkelongchem.com |
Indigo Naturalis S1 | Xianyou, Fujian | 20210501 | |
Indigo Naturalis S2 | Yaan, Sichuan | 20201102 | |
Indigo Naturalis S3 | Xianyou, Fujian | 20161012 | |
Indigo Naturalis S4 | Xianyou, Fujian | 20180305 | |
Iron ring | Chengdu Kelong Chemical Co. LTD | / | www.cdkelongchem.com |
Iron stand | Chengdu Kelong Chemical Co. LTD | / | www.cdkelongchem.com |
Mili-Q ultra-pure water meter | Milipore, USA | Mili-Q | www.merckmillipore.com |
Ninth sieve | Chengdu Kelong Chemical Co. LTD | Average aperture size 75 µm | www.cdkelongchem.com |
Sample bottle | French Formulaction Company | Bottom diameter 2.6 cm, height 6 cm | www.formulaction.com |
Seventh sieve | Chengdu Kelong Chemical Co. LTD | Average aperture size 125 µm | www.cdkelongchem.com |
Turbisoft Lab multiple light scattering instrument | French Formulaction Company | Turbisoft Lab 2.3.1.125 Fanalyser 1.3.5 | www.formulaction.com |
Weighing paper | Chengdu Kelong Chemical Co. LTD | / | www.cdkelongchem.com |