ABSTRACT
Diagnostic ions filter method was used to rapidly detect and identify the phenolic compounds in Rheum palmatum based on ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MSE). The representative authentic standards of phenolic compounds, including gallic acid, (+)-catechin, (－)-epicatechin, (－)-epicatechin-3-O-gallate and procyanidin B2, were subjected to analysis by UPLC-Q-TOF/MSE system with negative ion mode. Fragmentation patterns of each standard were summarized based on assigned fragment ions. The prominent product ions were selected as diagnostic ions. Subsequently, diagnostic ions filter was employed to rapidly recognize analogous skeletons. Combined with retention time, accurate mass, characteristic fragments and previous literature data, the structures of the filtered compounds were identified or tentatively characterized. A total 63 phenolic compounds (36 phenolic acid derivatives, 8 flavonoid derivatives and 19 tennis derivatives) in R. palmatum were identified, including 6 potential new compounds. The method of diagnostic ions filter could rapidly detect and identify phenolic compounds in R. palmatum This study provides a method for rapid detection of phenolic compounds in R. palmatum and is expected to complete the material basis of rhubarb.
ABSTRACT
To establish an HPLC (high performance liquid chromatography) method for the simultaneous content determination of gallic acid, (+)-catechin, (－)-epicatechin-3-O-gallate, isolindleyin, 4-(4'-hydroxyphenyl)-2-butanone, emodin, chrysophanol, physcion, aloe-emodin, rhein, lindleyin, 4-(4'-hydroxyphenyl)-2-butanone-4'-O-β-D-(2″-O-galloyl-6″-O-cinnamoyl)-glucopyranoside, sennoside A and sennoside B in Rhei Radix et Rhizoma. The analysis was performed on Agilent Zorbax SB-C₁₈ (4.6 mm×150 mm, 5 μm) with 0.05% phosphoric acid solution (A) - acetonitrile (B) as mobile phase for gradient elution. The flow rate was 1 mL•min⁻¹, with column temperature of 40 ℃ and the wavelength was set at 268 nm. All calibration curves showed good linearity (r > 0.999 9) within the concentration range. Both the intra- and inter-day precision for 14 analytes was less than 3.1%, with the mean recovery at the range of 91.80%-104.1%. Meanwhile, quantitative determination was carried out for 10 qualified samples from Rheum palmatum and 10 qualified samples from R. tanguticum, respectively. It was found that the content of 4-(4'-hydroxyphenyl)-2-butanone and aloe-emodin were higher in the R. tanguticum and R. palmatum, respectively, and the content of all the compounds was different in each sample. The established HPLC method for simultaneous content determination of 14 compounds from Rhei Radix et Rhizoma could be used for quantitative assessment and quality control of Rhei Radix et Rhizoma.