Effect of processing method on chemical constituents of Rehmanniae Radix: based on UHPLC-LTQ-Orbitrap MS / 中国中药杂志

This study aims to explore the chemical composition of Rehmanniae Radix braised with mild fire and compare the effect of processing method on the chemical composition of Rehmanniae Radix. To be specific, ultra-high performance liquid chromatography with linear ion trap-orbitrap mass spectrometry(UHPLC-LTQ-Orbitrap MS) was used to screen the chemical constituents of Rehmanniae Radix. The chemical constituents were identified based on the relative molecular weight and fragment ions, literature information, and Human Metabolome Database(HMDB). The ion peak area ratio of each component before and after processing was used as the index for the variation. SIMCA was employed to establish principal component analysis(PCA) and orthogonal partial least squares discriminant analysis(OPLS-DA) models of different processed products. According to the PCA plot, OPLS-DA plot, and VIP value, the differential components before and after the processing were screened out. The changes of the content of differential components with the processing method were analyzed. A total of 66 chemical components were identified: 57 of raw Rehmanniae Radix, 55 of steamed Rehmanniae Radix, 55 of wine-stewed Rehmanniae Radix, 51 of repeatedly steamed and sundried Rehmanniae Radix Praeparata, 62 of traditional bran-braised Rehmanniae Radix, and 63 of electric pot-braised Rehmanniae Radix. Among them, the 9 flavonoids of braised Rehmanniae Radix were from Citri Reticulatae Pericarpium. PCA suggested significant differences in the chemical composition of Rehmanniae Radix Praeparata prepared with different processing methods. OPLS-DA screened out 32 chemical components with VIP value >1 as the main differential components. Among the differential components, 9 were unique to braised Rehmanniae Radix(traditional bran-braised, electric pot-braised) and the degradation rate of the rest in braised(traditional bran-braised, electric pot-braised) or repeatedly steamed and sundried Rehmanniae Radix was higher than that in the steamed or wine-stewed products. The results indicated the chemical species and component content of Rehmanniae Radix changed significantly after the processing. The 32 components, such as rehmapicrogenin, martynoside, jionoside D, aeginetic acid, hesperidin, and naringin, were the most important compounds to distinguish different processed products of Rehmanniae Radix. The flavonoids introduced by Citri Reticulatae Pericarpium as excipient may be the important material basis for the effectiveness of braised Rehmanniae Radix compared with other processed products.

Acetylation of Rehmannia glutinosa polysaccharides and antioxidant activity of acetylated derivatives / 中国中药杂志

This study aims to acetylate Rehmannia glutinosa polysaccharides by acetic anhydride method, optimize process parameters and evaluate their antioxidant activity. With the degree of substitution(D_s) as a criterion, the effects of reaction time, acetic anhydride-to-polysaccharides ratio and temperature were investigated. Process parameters were optimized by single-factor experiment and response surface methodology. The infrared spectroscopy(IR) and scanning electron microscopy(SEM) proved the successful acetylation and were employed to preliminarily analyze the structural characteristics of acetylated derivatives. The results showed that the D_s was 0.327 under the optimal technological conditions, including m(acetic anhydride):m(R. glutinosa polysaccharides)=2.70, reaction time 3.0 h and temperature 48 ℃. Further, the antioxidant properties of acetylated derivatives were investigated in vitro and acetylation was found effective to improve the antioxidant activity of R. glutinosa polysaccharides. This study provides a reference for the further development and application of R. glutinosa polysaccharides.

A combined quality evaluation method that integrates chemical constituents, appearance traits and origins of raw Rehmanniae Radix pieces / 中国天然药物

The quality control of Chinese herbal medicine is a current challenge for the internationalization of traditional Chinese medicine. Traditional quality evaluation methods lack quantitative analysis, while modern quality evaluation methods ignore the origins and appearance traits. Therefore, an integrated quality evaluation method is urgent in need. Raw Rehmanniae Radix (RRR) is commonly used in Chinese herbal medicine. At present, much attention has been drwan towards its quality control, which however is limited by the existing quality evaluation methods. The present study was designed to establish a comprehensive and practical method for the quality evaluation and control of RRR pieces based on its chemical constituents, appearance traits and origins. Thirty-three batches of RRR pieces were collected from six provinces, while high-performance liquid chromatography (HPLC) was applied to determine the following five constituents, including catalpol, rehmannioside A, rehmannioside D, leonuride and verbascoside in RRR pieces. Their appearance traits were quantitatively observed. Furthermore, correlation analysis, principal components analysis (PCA), cluster analysis and t-test were performed to evaluate the qualities of RRR pieces. These batches of RRR pieces were divided into three categories: samples from Henan province, samples from Shandong and Shanxi provinces, and those from other provinces. Furthermore, the chemical constituents and appearance traits of RRR pieces were significantly different from diverse origins. The combined method of chemical contituents, appearance traits and origins can distinguish RRR pieces with different qualities, which provides basic reference for the quality control of Chinese herbal medicine.