Search

In this study, flavonoids were extracted using accelerated solvent extraction (ASE) with 80% aqueous methanol. A high-performance liquid chromatography equipped with photodiode array detection and coupled with an electrospray ionization tandem mass spectrometry (HPLC–PDA–ESI/MSn) method has been developed for rapid identification and quantification of flavonoids in the plant extract of Rheum palmatum L. (RPL) seeds from Qinghai. Ten flavonoids from methanolic extract of RPL seeds were screened, of which epicatechin, myricetin, hyperoside, quercitrin and quercetin were identified and quantitatively analyzed for the first time. The absorbance was monitored at 280 nm for epicatechin and 360 nm for other four flavonoids. It was found that the calibration curves for all five analytes showed a good linearity (r2 > 0.999) within the test range and the data of the limit of detection (LOD) and limit of quantification (LOQ) for all investigated compounds were less than 2.98 μg mL−1 based on PDA. The relative standard deviation (R.S.D) values of the intra- and inter-day precisions were 0.98% and 1.65%, respectively. The range of mean recoveries of the five components was 91.3–93.9%, and the R.S.D was 1.3–2.9%. It was also found that the content of quercitrin is the highest in RPL seeds while the contents of epicatechin and myricetin are relatively lower. In addition, the validation procedure confirmed that this method was suitable for providing quality control evaluation of RPL seeds to ensure the therapeutic benefits. Keywords: Seeds of Rheum palmatum L., Identification, Quantification, Flavonoids, Accelerated solvent extraction, HPLC–PDA–ESI/MSn

Inula racemose Hook.f. ( I . racemosa ) is a traditional herbal medicine with strong anti-fungal and anti-inflammation activity while alantolactone (AL) and isoalantolactone (IAL) are the major active compounds of this plant. The aim of this paper was obtaining AL and IAL from the radix of I . racemosa by supercritical fluid extraction (SFE) which was optimized by response surface methodology (RSM). Our results showed that, the optimal conditions for maximum extraction efficiency were as follows: pressure 20 MPa, extraction temperature 50 °C, carbon dioxide (CO 2 ) flow rate of 17.0 × 10 −5 kg/s and extraction time of 40 min. Subsequently, an efficient freezing method was developed for purification of AL and IAL in the crude extract obtained from SFE. After purification by freezing, the total content of the target compounds was greatly improved by 30.7%. The results demonstrate that SFE coupled with freezing would be a powerful technique for extraction and purification of AL and IAL from the radix of I . racemosa .

An effective method for the rapid separation and purification of three stilbenes from the radix of Polygonum cillinerve (Nakai) Ohwl by macroporous resin column chromatography combined with high-speed counter-current chromatography (HSCCC) was successfully established. In the present study, a two-phase solvent system composed of chloroform-n-butanol-methanol-water (4:1:4:2, v/v/v/v) was used for HSCCC separation. A one-step separation in 4 h from 150 mg of crude extract produced 26.3 mg of trans-resveratrol-3-O-glucoside, 42.0 mg of pieceid-2"-O-gallate, and 17.9 mg of trans-resveratrol with purities of 99.1%, 97.8%, and 99.4%, respectively, as determined by high-performance liquid chromatography (HPLC). The chemical structures of these compounds were identified by nuclear magnetic resonance (NMR) spectroscopy.

Gentiana straminea is the famous Tibetan folk medicine thought to cure various diseases. Historically, the Qinghai-Tibetan region has been considered as the geo-authentic production area of "Mahua Jiao," where large quantities of the medicine are grown. However, there is still little known about the phytochemical constituent spatial variation of this species. In order to find the differences between the main phytochemical constituents of G. straminea and to provide comprehensive information for quality evaluation, four main bioactive compounds (loganic acid, swertiamarin, gentiopicroside and sweroside) were analysed in 26 populations grown in areas with elevations ranging from 2320 to 4720 m across the Qinghai-Tibetan Plateau. The results showed that the four phytochemical constitutes' concentrations varied greatly in the spatial profiling of the Qinghai-Tibetan region. Throughout the range of distribution of this species, no altitudinal, latitudinal or longitudinal trends have proven to be significant in any of the four constitutes' concentrations or their summation. Furthermore, hierarchical clustering analysis and statistical tests showed that four populations (Liu0609-18, Liu0609-15, Liu2006-13-9 and Liu0609-22) had total constitute contents that were higher than other populations. The spatial profiling of the four phytochemical constituents suggests that the geo-authentic producing area of this species exists at a few regions within the Qinghai province, which could be attributed to specific environmental or genetic factors.