Rhubarb-based Chinese herbal formulae for hepatic encephalopathy: a systematic review and Meta-analysis

Two-dimensional correlation spectroscopy indicates the infrared spectral markers of the optimum scorching degree of rhubarb (Rhei Radix et Rhizoma) to enhance the anti-inflammatory activity

Rhubarb has been used as herbal purgative with a long and worldwide history. But purgation is a side effect of rhubarb in many cases. In traditional Chinese medicine, rhubarb can be stir-baked to scorch to attenuate the purgative function while enhance other bioactivities such as the anti-inflammatory effect. However, the over-scorched rhubarb will lose necessary active ingredients and even generate toxic ingredients. Nowadays, the scorching degree of rhubarb is still determined by the intuitive observation of color changes in production. Therefore, this research was designed to develop more reasonable and objective criteria to evaluate the scorching degree to ensure the efficacy, safety and consistency of the scorched rhubarb. Taking the example of the rhubarb baked at 200 °C for different times, the combination of trait indicator (color), chemical indicator (combined and free AQs, sennosides, gallic acid, 5-HMF) and biological indicator (anti-inflammatory) showed that the rhubarb baked for 30 min can be treated as the right scorched. Two-dimensional correlation spectroscopy helped to reveal the infrared spectral markers of the water extract near 1694 cm^-1, 1442 cm^-1 and 825 cm^-1, as well as the relative strength of the absorption bands of the powder near 1610 cm^-1 and 1020 cm^-1, to discriminate the right-scorched and over-scorched rhubarb. In conclusion, the combination of trait, chemical and biological indicators can provide reasonable and objective criteria for the optimum scorching degree of rhubarb, while FTIR spectroscopy can assess the right endpoint of the scorching process in a rapid, cheap and green way.

Color-reflected chemical regulations of the scorched rhubarb (Rhei Radix et Rhizoma) revealed by the integration analysis of visible spectrophotometry, Fourier transform infrared spectroscopy and high performance liquid chromatography

Rhubarb has been used as herbal purgative with a worldwide long history. In traditional Chinese medicine, rhubarb can be stir-baked to scorch to eliminate the purgative function when it is a side effect. Under-scorched rhubarb still has the side effect of purgative, while over-scorched rhubarb can lose all bioactivities. Empirically, the degree of scorching is determined by manual observation of the rhubarb color. In order to find the reasonable and objective scorching endpoint criteria, visible spectrophotometry, FTIR spectroscopy and HPLC were used to reveal the color-reflected chemical changes. It was found that the blackening of rhubarb corresponded to the elimination of combined anthraquinones and the rise-fall inflection of free anthraquinones. The scorching endpoint criteria should include the upper limit for combined anthraquinones to avoid under-scorch and the lower limit for free anthraquinones to avoid over-scorch. Visible and FTIR spectroscopy can be process analytical techniques for the rhubarb scorching.

What we already know about rhubarb: a comprehensive review

Rhubarb (also named Rhei or Dahuang), one of the most ancient and important herbs in traditional Chinese medicine (TCM), belongs to the Rheum L. genus from the Polygonaceae family, and its application can be traced back to 270 BC in "Shen Nong Ben Cao Jing". Rhubarb has long been used as an antibacterial, anti-inflammatory, anti-fibrotic and anticancer medicine in China. However, for a variety of reasons, such as origin, variety and processing methods, there are differences in the effective components of rhubarb, which eventually lead to decreased quality and poor efficacy. Additionally, although some papers have reviewed the relationship between the active ingredients of rhubarb and pharmacologic actions, most studies have concentrated on one or several aspects, although there has been great progress in rhubarb research in recent years. Therefore, this review aims to summarize recent studies on the geographic distribution, taxonomic identification, pharmacology, clinical applications and safety issues related to rhubarb and provide insights into the further development and application of rhubarb in the future.

Network Pharmacology-Based Approaches of Rheum undulatum Linne and Glycyrriza uralensis Fischer Imply their Regulation of Liver Failure with Hepatic Encephalopathy in Mice

Rheum undulatum and Glycyrrhiza uralensis have been used as supplementary ingredients in various herbal medicines. They have been reported to have anti-inflammatory and antioxidant effects and, therefore, have potential in the treatment and prevention of various liver diseases. Considering that hepatic encephalopathy (HE) is often associated with chronic liver failure, we investigated whether an R. undulatum and G. uralensis extract mixture (RG) could reduce HE. We applied systems-based pharmacological tools to identify the active ingredients in RG and the pharmacological targets of RG by examining mechanism-of-action profiles. A CCl₄-induced HE mouse model was used to investigate the therapeutic mechanisms of RG on HE. We successfully identified seven bioactive ingredients in RG with 40 potential targets. Based on an integrated target–disease network, RG was predicted to be effective in treating neurological diseases. In animal models, RG consistently relieved HE symptoms by protecting blood–brain barrier permeability via downregulation of matrix metalloproteinase-9 (MMP-9) and upregulation of claudin-5. In addition, RG inhibited mRNA expression levels of both interleukin (IL)-1β and transforming growth factor (TGF)-β1. Based on our results, RG is expected to function various biochemical processes involving neuroinflammation, suggesting that RG may be considered a therapeutic agent for treating not only chronic liver disease but also HE.