Integration of magnetic solid phase fishing and off-line two-dimensional high-performance liquid chromatography–diode array detector–mass spectrometry for screening and identification of human serum albumin binders from Radix Astragali

Astragaloside I Promotes Lipophagy and Mitochondrial Biogenesis to Improve Hyperlipidemia by Regulating Akt/mTOR/TFEB Pathway

The simultaneous enhancement of lipophagy and mitochondrial biogenesis has emerged as a promising strategy for lipid lowering. The transcription factor EB (TFEB) exhibits a dual role, whereby it facilitates the degradation of lipid droplets (LDs) through the process of lipophagy while simultaneously stimulating mitochondrial biogenesis to support the utilization of lipophagy products. The purpose of this study was to explore the effect of astragaloside I (AS I) on hyperlipidemia and elucidate its underlying mechanism. AS I improved serum total cholesterol and triglyceride levels and reduced hepatic steatosis and lipid accumulation in db/db mice. AS I enhanced the fluorescence colocalization of LDs and autophagosomes and promoted the proteins and genes related to the autolysosome. Moreover, AS I increased the expression of mitochondrial biogenesis-related proteins and genes, indicating that AS I promoted lipophagy and mitochondrial biogenesis. Mechanistically, AS I inhibits the protein level of p-TFEB (ser211) expression and promotes TFEB nuclear translocation. The activation of TFEB by AS I was impeded upon the introduction of the mammalian target of rapamycin (mTOR) agonist MHY1485. The inhibition of p-mTOR by AS I and the activation of TFEB were no longer observed after administration of the Akt agonist SC-79, which indicated that AS I activated TFEB to promote lipophagy-dependent on the Akt/mTOR pathway and may be a potentially effective pharmaceutical and food additive for the treatment of hyperlipidemia.

A comprehensive quality evaluation for Huangqi Guizhi Wuwu decoction by integrating UPLC-DAD/MS chemical profile and pharmacodynamics combined with chemometric analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Huangqi Guizhi Wuwu Decoction (HGWD), a classical Chinese formula originally recorded in Jin Kui Yao Lue, was used for the treatment of human "blood impediment" (a type of "Bi" syndrome). In clinical practice, HGWD has been applied to treat rheumatoid arthritis (RA).

AIM OF THE STUDY

The characterization of chemical markers reflecting both efficacy and chemical characteristics is of great significance for TCM quality control. With the anti-RA effects of HGWD as an example, the aim of this study was to develop a comprehensive strategy combining the overall chemical profile and biological activity data to identify chemical markers.

MATERIALS AND METHODS

First, an ultra-performance liquid chromatography-diode array detector (UPLC-DAD) fingerprint was established and validated to evaluate the holistic quality of HGWD of different origins. Characteristic markers associated with HGWD from different geographical origins were screened by a combination of UPLC-DAD fingerprint and chemometrics methods. Second, the chemical profiles of the 15 batches of HGWD samples were characterized by UPLC coupled tohybrid linear ion trap-Orbitrap mass spectrometry (UPLC-HRMS). The in vitro anti-RA activities of the 15 HGWD samples were then evaluated. Third, spectrum-effect relationship analysis was performed to identify bioactive compounds that could potentially be used as quality markers. Finally, a UPLC-triple quadrupole tandem mass spectrometry approach was optimized and established for quantitative analysis of the characteristic and quality markers in 15 batches of HGWD.

RESULTS

In total, 30 common peaks were assigned in the UPLC-DAD fingerprint. Nine peaks were recognized and considered characteristic markers: protocatechuic acid, coumarin, cinnamic acid, oxypaeoniflorin, paeoniflorin, calycosin, formononetin, catechin, and albiflorin. Furthermore, ninety-five common compounds were identified in the UPLC-HRMS chemical profile. The pharmacological analysis indicated that the anti-RA activities of the 15 HGWD samples were vastly different. The spectrum-effect relationship analysis revealed 30 potential bioactive constituents positively correlated with anti-RA activity. Among them, five compounds with relative amounts >1%, paeoniflorin, astragaloside IV, hexahydrocurcumin, formononetin and calycosin-7-glucoside, were selected as quality markers, and their activity was verified in LPS-induced RAW264.7 macrophages. Finally, the above 12 representative components were simultaneously quantified in the 15 batches of HGWD samples.

CONCLUSION

Combining a holistic chemical profile with representative component evaluation, this systematic strategy could be a reliable and effective method to improve quality evaluations of HGWD.

Two-dimensional chromatography in screening of bioactive components from natural products

INTRODUCTION

Screening and analysis of bioactive components from natural products is a fundamental part of new drug development and innovation. Two-dimensional (2D) chromatography has been demonstrated to be an effective method for screening and preparation of specific bioactive components from complex natural products.

OBJECTIVE

To collect details of application of 2D chromatography in screening of natural product bioactive components and to outline the research progress of different separation mechanisms and strategies.

METHODOLOGY

Three screening strategies based on 2D chromatography are reviewed, including traditional separation-based screening, bioactivity-guided screening and affinity chromatography-based screening. Meanwhile, in order to cover these aspects, selections of different separation mechanisms and modes are also presented.

RESULTS

Compared with traditional one-dimensional (1D) chromatography, 2D chromatography has unique advantages in terms of peak capacity and resolution, and it is more effective for screening and identifying bioactive components of complex natural products.

CONCLUSION

Screening of natural bioactive components using 2D chromatography helps separation and analysis of complex samples with greater targeting and relevance, which is very important for development of innovative drug leads.

Rapid profiling of potential antitumor polymethoxylated flavonoids in natural products by integrating cell biospecific extraction with neutral loss/diagnostic ion filtering-based high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry

INTRODUCTION

Citri Reticulatae Pericarpium Viride (CRPV, Qing Pi in Chinese) has been widely used in traditional Chinese medicine. Polymethoxylated flavonoids (PMFs), which are a special group of flavonoids with strong antitumor activity, are broadly distributed in citrus peels. However, systematic investigation of antitumor PMFs in CRPV has received little attention to date.

OBJECTIVES

An MCF-7 cell biospecific extraction method integrated with neutral loss/diagnostic ion filtering-based HPLC-QTOF-MS/MS strategy was developed for rapid and specific profiling of antitumor PMFs and systematic identification of PMFs in CRPV.

METHODOLOGY

By incubating MCF-7 cells with CRPV extract, potential antitumor PMFs specifically bound to cells and were isolated. Then, by systematic investigation of fragmentation pathways, neutral loss and diagnostic ion filtering strategies were proposed to comprehensively and accurately identify PMFs.

RESULTS

Sixteen antitumor PMFs were unambiguously or tentatively identified. Among them, minor compound 15 (5-hydroxy-6,7,8,3',4'-pentamethoxyflavone with a free hydroxyl group at C-5) exhibited excellent antitumor activity, with an IC₅₀ value of 2.81 ± 0.76 μg/mL, which is lower than that of 5-fluorouracil (IC₅₀ , 4.92 ± 0.83 μg/mL). Nobiletin (12) and tangeretin (16), two major PMFs, presented moderate antitumor activities with IC₅₀ values of 13.06 ± 1.85 and 17.07 ± 1.18 μg/mL, respectively, and their contents were sensitively and precisely determined.

CONCLUSIONS

To the best of our knowledge, this is the first report on the systematic investigation of antitumor PMFs in CRPV. The study will lay a foundation for the quality control and clinical application of CRPV.

Bioactive pterocarpans from the root of Astragalus membranaceus var. mongholicus

Eleven undescribed and three known pterocarpans were isolated and identified from the traditional Chinese medicine "Huang-qi", Astragali Radix (the root of Astragalus membranaceus var. mongholicus (Bunge) P.K.Hsiao). The structures of these pterocarpans were determined using spectroscopic, X-ray crystallographic, quantum chemical calculation, and chemical methods. Pterocarpans, almost exclusively distributed in the family of Leguminosae, are the second largest subgroup of isoflavanoids. However, pterocarpan glycoside number is limited, most of which are glucosides, and only one pterocarpan apioside was isolated from nature. Notably, nine rare apiosyl-containing pterocarpan glycosides were isolated and identified. The hypoglycemic activities of all these compounds were evaluated using α-glucosidase and DPP-IV inhibitory assays respectively, and some isolates displayed the α-glucosidase inhibitory function. The antioxidant activities of all compounds were evaluated using the ORAC and DPPH radical scavenging assays, respectively. All compounds exhibited varying degrees of oxygen radical absorbance capacity, and some compounds displayed DPPH radical scavenging ability.

Colour, chemical compounds, and antioxidant capacity of Astragali Radix based on untargeted metabolomics and targeted quantification

INTRODUCTION

Astragali Radix has been used for over 2000 years in traditional Chinese medicine. Its secondary xylem "Jinjing" and secondary phloem "Yulan" are important for evaluating the quality of the Daodi medicinal material in China. However, its systematic characterisation has not been conducted.

OBJECTIVE

This study aims to investigate the colour, chemical compounds, and antioxidant capacity of the secondary xylem and phloem of Astragali Radix on the basis of untargeted metabolomics, broadening the application scope of Astragali Radix in food and pharmaceutical industries.

METHODS

The L*, a*, and b* of the secondary xylem and phloem were measured by colorimetry, and the chemical compounds were identified and quantified by ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS) and high-performance liquid chromatography-diode array detector-evaporative light scattering detection. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays were conducted to evaluate their antioxidant capacity.

RESULTS

Thirty-one compounds were identified by UPLC-Q-TOF-MS. The secondary xylem exhibited high parameter b*, flavonoid content, and antioxidant capacity, while the secondary phloem was rich in astragalosides. The colour parameters of well-defined type A significantly varied from those of the other types. Well-defined type A also exhibited the highest antioxidant activity and flavonoid content, followed by middle type A-like, middle type B-like, and yellow shading type B.

CONCLUSION

The colour parameters, chemical compounds, and antioxidant capacity among the different transverse sections of secondary xylem and phloem varied. The yellow colour of secondary xylem was correlated to high flavonoid content and antioxidant activity, and well-defined type A of Astragali Radix had better quality than other types.

Magnetic Ligand Fishing Using Immobilized Cyclooxygenase-2 for Identification and Screening of Anticoronary Heart Disease Ligands From Choerospondias axillaris

Inhibition of cyclooxygenase-2 (COX-2) activity is an effective way for treatment of coronary heart disease. And as an important source of COX-2 inhibitors, bioactive compounds of Choerospondias axillaris and pharmacological mechanisms remained lacking in prospective researches. Therefore, for the purpose of accelerating the discovery of natural products targeting designed inhibitors, the COX-2 microreactor composed of functionalized microspheres and magnetic ligand fishing was developed and applied in Choerospondias axillaris, and the physicochemical properties of the COX-2 functionalized microspheres were characterized using Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, the bioactive compounds singled out from ethanol decoction without prepurification were dissociated and identified by ultraperformance liquid chromatography plus Q-Exactive Orbitrap tandem mass spectrometry (UPLC-Q-Exactive Orbitrap-MS/MS). Consequently, 21 bioactive compounds consisting of 6 organic acids, 8 flavonoids, and 7 others were separated and characterized from Choerospondias axillaris, which were reported to participate in the COX-2 inhibitory pathway to varying degrees. Therefore, this method could provide a prospective solution for the extraction and identification of active pharmaceutical ingredients and the rapid screening of some enzyme inhibitors in the complex mixtures.

A novel cell membrane-cloaked magnetic nanogripper with enhanced stability for drug discovery

Cell membrane-cloaked nanotechnology has attracted increasing attention owing to its unique bionic properties, such as specific recognition and biocompatibility conferred by the integrated membrane structure and receptors. However, this technology is limited by the dissociation of the cell membrane from its carrier. Here, we report a novel type of cell membrane-cloaked modified magnetic nanoparticle with good stability in drug discovery. High α1A-adrenergic receptor (α1A-AR) expressing HEK293 cell membrane-cloaked magnetic nanogrippers (α1A/MNGs) were used as a platform for the specific targeting and binding of α1A-AR antagonists as candidate bioactive compounds from traditional Chinese medicine (TCM). Furthermore, using a dynamic covalent bonding approach, α1A/MNGs showed great stability with positive control drug recoveries of α1A/MNGs showing almost no decline after use in five adsorption-desorption cycles. Moreover, the α1A/MNGs possessed a unilamellar membrane with magnetic features and exhibited good binding capacity and selectivity. Ultimately, TCM and pharmacological studies of the bioactivity of the screened compounds confirmed the considerable targeting and binding capability of α1A/MNGs. Application of aldehyde group modification in this drug-targeting concept further improved biomaterial stability and paves the way for the development of new drug discovery strategies. More importantly, the successful application of α1A/MNGs provides new insights into methodologies to improve the integration of cell membranes with the nanoparticle platform.

Recent applications of immobilized biomaterials in herbal analysis

Immobilization of biomaterials developed rapidly due to the great promise in improving their stability, activity and even selectivity. In this review, the immobilization strategies of biomaterials, including physical adsorption, encapsulation, covalent attachment, cross-linking and affinity linkage, were briefly introduced. Then, the major emphasis was focused on the reported various types of immobilized biomaterials, including proteins, enzymes, cell membrane and artificial membrane, living cells, carbohydrates and bacteria, used in the herbal analysis for bioactive compound screening, drug-target interaction evaluation and chiral separation. In addition, a series of carrier materials applied in biomaterials immobilization, such as magnetic nanoparticles, metal-organic frameworks, silica capillary column, cellulose filter paper, cell membrane chromatography, immobilized artificial membrane chromatography and hollow fiber, were also discussed. Perspectives on further applications of immobilized biomaterials in herbal analysis were finally presented.

Screening techniques for the identification of bioactive compounds in natural products

Natural products (NPs) have a long history of clinical use and are rich source of bioactive compounds. The development of tools and techniques for identifying and analyzing NP bioactive compounds to ensure their quality and discover new drugs is thus very important and still in demand. Screening techniques have proven highly useful for screening and analyzing active components in complex mixtures, which rely on cell culture, dialysis, ultrafiltration, chromatographic methods and target molecule immobilization, using biological targets to identify the active compounds. The recent progress in biological screening techniques in the field of natural products is reviewed here. This includes a review on the strategy and application of the screening methods, their detailed description and discussion of their existing limitations of the different models along with prospective in future development of screening techniques.

Antiproliferative Activity of Neem Leaf Extracts Obtained by a Sequential Pressurized Liquid Extraction

Azadirachta indica A. Juss (neem) extracts have been used in pharmaceutical applications as antitumor agents, due to their terpenes and phenolic compounds. To obtain extracts from neem leaves with potential antiproliferative effect, a sequential process of pressurized liquid extraction was carried out in a fixed bed extractor at 25 °C and 100 bar, using hexane (SH), ethyl acetate (SEA), and ethanol (SE) as solvents. Extractions using only ethanol (EE) was also conducted to compare the characteristics of the fractionated extracts. The results obtained by liquid chromatography-electrospray ionization mass spectrometry suggested a higher concentration of terpenes in the SEA extract in comparison to SH, SE, and EE extracts. Therefore, antiproliferative activity showed that SEA extracts were the most efficient inhibitor to human tumor cells MCF-7, NCI-H460, HeLa, and HepG2. Hepatocellular cells were more resistant to SH, SEA, SE, and EE compared to breast, lung, hepatocellular, and cervical malignant cells. Neem fractioned extracts obtained in the present study seem to be more selective for malignant cells compared to the non-tumor cells.

Rapid Colorimetric Detection of Cartap Residues by AgNP Sensor with Magnetic Molecularly Imprinted Microspheres as Recognition Elements

The overuse of cartap in tea tree leads to hazardous residues threatening human health. A colorimetric determination was established to detect cartap residues in tea beverages by silver nanoparticles (AgNP) sensor with magnetic molecularly imprinted polymeric microspheres (Fe₃O₄@mSiO₂@MIPs) as recognition elements. Using Fe₃O₄ as supporting core, mesoporous SiO₂ as intermediate shell, methylacrylic acid as functional monomer, and cartap as template, Fe₃O₄@mSiO₂@MIPs were prepared to selectively and magnetically separate cartap from tea solution before colorimetric determination by AgNP sensors. The core-shell Fe₃O₄@mSiO₂@MIPs were also characterized by FT-IR, TEM, VSM, and experimental adsorption. The Fe₃O₄@mSiO₂@MIPs could be rapidly separated by an external magnet in 10 s with good reusability (maintained 95.2% through 10 cycles). The adsorption process of cartap on Fe₃O₄@mSiO₂@MIPs conformed to Langmuir adsorption isotherm with maximum adsorption capacity at 0.257 mmol/g and short equilibrium time of 30 min at 298 K. The AgNP colorimetric method semi-quantified cartap ≥5 mg/L by naked eye and quantified cartap 0.1–5 mg/L with LOD 0.01 mg/L by UV-vis spectroscopy. The AgNP colorimetric detection after pretreatment with Fe₃O₄@mSiO₂@MIPs could be successfully utilized to recognize and detect cartap residues in tea beverages.

Magnetic surface molecularly imprinted poly(3-aminophenylboronic acid) for selective capture and determination of diethylstilbestrol

Imprinted poly(APBA) nanoshell on Fe₃O₄@SiO₂ surface was first synthesized and used for MSPE of diethylstilbestrol followed by HPLC determination.

Bioactive compounds of Shuang-Huang-Lian prescription and an insight into its binding mechanism by β2 -adrenoceptor chromatography coupled with site-directed molecular docking

Owing to the promising clinical efficacy and relatively simple composition, Shuang-Huang-Lian prescription is widely prescribed for the treatment of acute upper respiratory tract infection and acute bronchitis in practice. This necessitates the understanding of the bioactive compounds of the prescription and their binding mechanism to β₂ -adrenoceptor, which mediates the aforementioned ailments. In this work, a column containing immobilized β₂ -adrenoceptor was prepared using a diazonium salt reaction. The bioactive compound collected from the β₂ -adrenoceptor column was identified as chlorogenic acid by using high-performance liquid chromatography coupled with ion trap mass spectrometry. Using an injection amount dependent method, chlorogenic acid proved the binding to β₂ -adrenoceptor through two kinds of sites. The numbers of the sites were (1.42 ± 0.03) × 10^-8 and (9.06 ± 0.49) × 10^-8  M. The association constants were (2.72 ± 0.01) × 10⁵ and (2.80 ± 0.01) × 10⁴  M^-1 , respectively. Molecular docking analysis of the interaction between chlorogenic acid and β₂ -adrenoceptor indicated that the binding mainly occurred on Ser¹⁶⁹ , Ser¹⁷³ , and Phe²⁸⁷ of β₂ -adrenoceptor. These results paved the way to screen bioactive compounds of other traditional medicines by receptor chromatography.

Analysis of binding properties and interaction of thiabendazole and its metabolite with human serum albumin via multiple spectroscopic methods

Thiabendazole (TBZ), which is oxidized into 5-hydroxythiabendazole (5-OH-TBZ) in vivo, is a commonly used food preservative. Interactions of TBZ and 5-OH-TBZ with human serum albumin (HSA) were comprehensively studied via multiple spectroscopic methods and molecular docking. This study focussed on the mechanistic and structural information on binding of TBZ and 5-OH-TBZ to HSA to evaluate the impact of the food additive on HSA. ¹H NMR spectra of the two ligands showed the binding exists. ITC and fluorescence spectroscopy results revealed that TBZ was a stronger ligand, with a binding constant of 10⁵l/mol and formed a more stable complex with HSA than did 5-OH-TBZ via electrostatic interaction. Spectroscopic results (UV-vis, FT-IR, and CD) showed that TBZ and 5-OH-TBZ caused conformational changes in HSA, in which α-helix and β-turn transformed into β-sheet, causing HSA structure to loosen. Docking programs showed that both TBZ and 5-OH-TBZ bound to HSA via IB.

Screening for the bioactive constituents of traditional Chinese medicines—progress and challenges

The search for lead compounds from traditional Chinese medicines (TCMs) may be promising for new drug development.

Screening and identifying antioxidants from Oplopanax elatus using 2,2'-diphenyl-1-picrylhydrazyl with off-line two-dimensional HPLC coupled with diode array detection and tandem time-of-flight mass spectrometry

The root of Oplopanax elatus (Nakai) Nakai has a well-known history of use for the treatment of diseases such as neurasthenia, cardiovascular disorders, and cancer by the native people in northeast China. It is important to screen and identify the bioactive molecules from its root rapidly. Hereby, an off-line two-dimensional high performance liquid chromatography coupled with diode array detection and tandem time-of-flight mass spectrometry together with 2,2'-diphenyl-1-picrylhydrazyl was established to screen antioxidants from the root of O. elatus. A Waters cyanogen column (150 × 3.9 mm, id, 4 μm) was used for the first dimensional liquid chromatography, while a Hypersil BDS-C18 column (250 × 4.6 mm, id, 5 μm) was installed for the second dimension liquid chromatographic analysis. Twenty-eight compounds had been tentatively identified from the methanol extract of the air-dried root of O. elatus including six polyynes and eight phenolic derivatives were screened with antioxidant activity. The developed method could be expedient for screening and identifying antioxidants from O. elatus.

Dynamic variation of bioactive compounds and aflatoxins in contaminated Radix Astragali during extraction process

BACKGROUND

Although increasing attention has been paid to the health threat caused by mycotoxins in commodities such as food or medicines, mycotoxin transfer processes from crude material to products have raised little concern so far. Radix Astragali is a commonly used edible and medicinal herbal plant that is susceptible to contamination with aflatoxins from Aspergillus flavus. There have been no studies on mycotoxin transfer into pharmaceutical preparations or derivative products.

RESULTS

To facilitate the aflatoxin reduction and bioactivity retention, the dynamic variations of aflatoxins as well as herbal compounds, namely calycosin-7-glucoside, astragaloside and formononetin, in Radix Astragali contaminated by A. flavus during water decoction and ethanol refluxing treatments were evaluated simultaneously by an ultra-fast liquid chromatography-triple quadrupole linear ion trap mass spectrometry method. After the extraction processes, although the amount of alfatoxins was reduced remarkably, aflatoxin residuals in preparation still exceed recommended limits, manifesting the great need to establish a limit for aflatoxins in herbal extractions or derivative products. Meanwhile, due to the hydrolysis of glucoside, water decoction period should be no longer than 4 h.

CONCLUSIONS

This investigation would benefit from the determination of the dynamic variation of aflatoxins in infected herbs in preparation treatments, in order to further develop aflatoxin limits in herbal preparations.

High-speed counter-current chromatography coupled online to high performance liquid chromatography-diode array detector-mass spectrometry for purification, analysis and identification of target compounds from natural products

A challenge in coupling high-speed counter-current chromatography (HSCCC) online with high performance liquid chromatography (HPLC) for purity analysis was their time incompatibility. Consequently, HSCCC-HPLC was conducted by either controlling HPLC analysis time and HSCCC flow rate or using stop-and-go scheme. For natural products containing compounds with a wide range of polarities, the former would optimize experimental conditions, while the latter required more time. Here, a novel HSCCC-HPLC-diode array detector-mass spectrometry (HSCCC-HPLC-DAD-MS) was developed for undisrupted purification, analysis and identification of multi-compounds from natural products. Two six-port injection valves and a six-port switching valve were used as interface for collecting key HSCCC effluents alternatively for HPLC-DAD-MS analysis and identification. The ethyl acetate extract of Malus doumeri was performed on the hyphenated system to verify its efficacy. Five main flavonoids, 3-hydroxyphloridzin (1), phloridzin (2), 4',6'-dihydroxyhydrochalcone-2'-O-β-D-glucopyranoside (3, first found in M. doumeri), phloretin (4), and chrysin (5), were purified with purities over 99% by extrusion elution and/or stepwise elution mode in two-step HSCCC, and 25mM ammonium acetate solution was selected instead of water to depress emulsification in the first HSCCC. The online system shortened manipulation time largely compared with off-line analysis procedure and stop-and-go scheme. The results indicated that the present method could serve as a simple, rapid and effective way to achieve target compounds with high purity from natural products.

Integrated analysis for identifying radix astragali and its adulterants based on DNA barcoding

Radix Astragali is a popular herb used in traditional Chinese medicine for its proimmune and antidiabetic properties. However, methods are needed to help distinguish Radix Astragali from its varied adulterants. DNA barcoding is a widely applicable molecular method used to identify medicinal plants. Yet, its use has been hampered by genetic distance, base variation, and limitations of the bio-NJ tree. Herein, we report the validation of an integrated analysis method for plant species identification using DNA barcoding that focuses on genetic distance, identification efficiency, inter- and intraspecific variation, and barcoding gap. We collected 478 sequences from six candidate DNA barcodes (ITS2, ITS, psbA-trnH, rbcL, matK, and COI) from 29 species of Radix Astragali and adulterants. The internal transcribed spacer (ITS) sequence was demonstrated as the optimal barcode for identifying Radix Astragali and its adulterants. This new analysis method is helpful in identifying Radix Astragali and expedites the utilization and data mining of DNA barcoding.

Efficient determination of protocatechuic acid in fruit juices by selective and rapid magnetic molecular imprinted solid phase extraction coupled with HPLC

Magnetic molecular imprinted polymers (MMIPs) have been prepared as solid phase material to selectively extract protocatechuic acid (PCA) from fruit juices with high capacity and fast binding kinetics. The resulting MMIPs were characterized by TEM, FT-IR, TGA, and VSM. The adsorption process between PCA and MMIPs followed Langumuir adsorption isotherm with maximum adsorption capacity at 7.5 mg/g and pseudo-second-order reaction kinetics with fast binding kinetics (equilibrium time at 40 min). In addition, the prepared MMIPs showed rapid magnetic separation (10 s) and reusability (retained 94.9% after six cycles). Subsequently, MMIPs were successfully applied for selective enrichment and determination of PCA from fruit juices (0.45 μg/mL in grape juice but not detected in apple juice, pineapple juice, orange juice, and peach juice) with satisfactory recoveries (92-107%). The results indicated that synthesized MMIPs can be used for efficient and selective extraction of PCA from complex matrices.

Rapid screening and identification of α-amylase inhibitors from Garcinia xanthochymus using enzyme-immobilized magnetic nanoparticles coupled with HPLC and MS

α-Amylase inhibitors play an important role in management of diabetes and obesity. In order to rapidly discover potent α-amylase inhibitors from medicinal plants, a ligands-screening method based on enzyme-immobilized magnetic nanoparticles integrated with HPLC was developed. Amine-terminated magnetic nanoparticles were prepared for the immobilization of α-amylase. Based on the affinity theory, the α-amylase-coated magnetic nanoparticles were employed to fish out the ligands from the extracts of Garcinia xanthochymus, and the elutes were examined by HPLC. As a result, three ligands were screened out. Isolation and identification were carried out subsequently. By analyzing the UV, MS and NMR spectra, they were identified as three biflavonoids including GB2a glucoside (2), GB2a (3) and fukugetin (4). The IC50 values of the three compounds were also determined. The results suggest the proposed approach is efficient and accurate, and has great potential in rapid discovery of drug candidates from medical plants.

Combined spectroscopy and cyclic voltammetry investigates the interaction between [(η6-p-cymene)Ru(benzaldehyde-N(4)-phenylthiosemicarbazone)Cl]Cl anticancer drug and human serum albumin

The interaction between Ru anticancer drug and HSA was investigated systematically under physiological conditions.