Li Yang,Le Yang,Suqin Sun,Qun Zhou,Ling Dong,Jianbo Chen
Rhubarb has a long history of medicinal applications in Asia and Europe. For some clinical applications of traditional Chinese medicine, rhubarb has to be stir-baked to scorch to eliminate the purgative activity, but increase the functions of blood-cooling and hemostasis. Understanding the chemical transitions during the stir-baking process is necessary for the quality assessment a quality control of scorched rhubarb. This research used the heated ATR-FTIR spectroscopy to study the thermal transitions of rhubarb and related compounds. Critical points during the heating process of rhubarb, emodin, emodin-8-glucoside, glucose and 5-HMF were recognized from PCA score plots. Two-dimensional correlation spectroscopy (2DCOS) was used to interpret the spectral changes of rhubarb during different thermal stages. It was found that the decomposition of anthraquinone glycosides and the formation of aromatic carbon networks at high temperature (above 170 °C) may be the primary reactions to generate scorched rhubarb. These results are helpful for the reasonable procedure optimization and quality control of the stir-baking process to produce scorched rhubarb.
Deep eutectic solvents (DESs), a new class of green and sustainable solvents, have shown a promising application prospect in the aqueous two-phase system (ATPS) extraction. In the present work, hexafluoroisopropanol (HFIP) was introduced as a hydrogen-bond donor to synthesize DESs with choline chloride (ChCl), decyltrimethylammonium bromide, dodecyltrimethylammonium bromide, and tetradecyltrimethylammonium bromide (hydrogen-bond acceptor), respectively. These HFIP-based DESs (HFIP-DESs) can form ATPS with various inorganic salts, and their phase separation ability is significantly stronger than that of small molecule aliphatic alcohols, HFIP, and traditional DESs. The ATPSs based on HFIP-DESs were first used to extract anthraquinones (AQs) from Rhei Radix et Rhizoma samples. Under the optimal conditions, more than 92% of AQs (including aloe-emodin, rhein, emodin, chrysophanol, and physcion) was enriched in the DES-rich phase of the ATPS composed of ChCl-HFIP DES and Na2SO4. Compared with the traditional chloroform extraction method (60 mL chloroform consumption), the ChCl-HFIP DES/Na2SO4 ATPS extraction method attained high extraction efficiency but only consumed 0.5 mL of organic solvent (HFIP).
Natural long-chain alkanol and alkyl carboxylic acid were used to prepare novel hydrophobic deep eutectic solvents (HDESs). These HDESs are liquid at room temperature and have low viscosity (<12.26 mPa‧s), low polarity (lower than that of methanol, ChCl-based deep eutectic solvents and other reported HDESs), and low density (<0.928 g/mL). A simple one-pot method based on a novel HDES–water two-phase extraction system was constructed for the extraction of weak-polarity bioactive components, anthraquinones, from Rhei Radix et Rhizoma. This HDES-based new extraction method does not consume hazardous organic solvents and can obtain a total anthraquinone yield of 21.52 mg/g, which is close to that obtained by the Chinese pharmacopoeia method (21.22 mg/g) and considerably higher than those by other reported HDESs-based extraction methods (14.20–20.09 mg/g, p < 0.01). The high extraction yield can be mainly attributed to the severe destruction of the RRR cell walls by the extraction system and the excellent dissolving ability of novel HDESs for anthraquinones.
危险品化学品经营许可证（带存储）