Structural characterization of isoprenylated flavonoids from Kushen by electrospray ionization multistage tandem mass spectrometry

Liquid Chromatography/Tandem Mass Spectrometry Analysis of Sophora flavescens Aiton and Protective Effects against Alcohol-Induced Liver Injury and Oxidative Stress in Mice

In this study, we investigated the hepatoprotective effects of an ethanol extract of Sophora flavescens Aiton (ESF) on an alcohol-induced liver disease mouse model. Alcoholic liver disease (ALD) was caused by the administration of ethanol to male C57/BL6 mice who were given a Lieber-DeCarli liquid diet, including ethanol. The alcoholic fatty liver disease mice were orally administered ESF (100 and 200 mg/kg bw/day) or silymarin (50 mg/kg bw/day), which served as a positive control every day for 16 days. The findings suggest that ESF enhances hepatoprotective benefits by significantly decreasing serum levels of aspartate transaminase (AST) and alanine transaminase (ALT), markers for liver injury. Furthermore, ESF alleviated the accumulation of triglyceride (TG) and total cholesterol (TC), increased serum levels of superoxide dismutase (SOD) and glutathione (GSH), and improved serum alcohol dehydrogenase (ADH) activity in the alcoholic fatty liver disease mice model. Cells and organisms rely on the Kelch-like ECH-associated protein 1- Nuclear factor erythroid 2-related factor 2 (Keap1-Nrf2) system as a critical defensive mechanism in response to oxidative stress. Therefore, Nrf2 plays an important role in ALD antioxidant responses, and its level is decreased by increased reactive oxidation stress (ROS) in the liver. ESF increased Nrf2, which was decreased in ethanol-damaged livers. Additionally, four polyphenol compounds were identified through a qualitative analysis of the ESF using LC-MS/MS. This study confirmed ESF's antioxidative and hangover-elimination effects and suggested the possibility of using Sophora flavescens Aiton (SF) to treat ALD.

The potential anti-Alzheimer's activity of Oxalis corniculata Linn. Methanolic extract in experimental rats: Role of APOE4/LRP1, TLR4/NF-κβ/NLRP3, Wnt 3/β-catenin/GSK-3β, autophagy and apoptotic cues

ETHNOPHARMACOLOGICAL RELEVANCE

Oxalis corniculata (O. corniculata) is a member of Oxalidaceae family, widely distributed in Asia, Europe, America, and Africa, used extensively as food and its traditional folkloric uses include management of epilepsy, gastric disorders, and neurodegenerative diseases, together with its use in enhancing health. Numerous pharmacological benefits of O. corniculata are linked to its anti-inflammatory and antioxidant abilities. One of the most prevalent neurodegenerative disorders is Alzheimer's disease (AD) in which neuroinflammation and oxidative stress are its main pathogenic processes.

AIM OF THE STUDY

Our research aimed to study the neuroprotective effect of the methanolic extract of Oxalis corniculata Linn. (O. corniculata ME), compared to selenium (Se) against AlCl3-induced AD.

MATERIALS AND METHODS

Forty male albino rats were allocated into four groups (Gps). Gp I a control group, the rest of the animals received AlCl3 (Gp II-Gp IV). Rats in Gp III and IV were treated with Se and O. corniculata ME, respectively.

RESULTS

The chemical profile of O. corniculata ME was studied using ultraperformance liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry, allowing the tentative identification of sixty-six compounds, including organic acids, phenolics and others, cinnamic acid and its derivatives, fatty acids, and flavonoids. AlCl3 showed deterioration in short-term memory and brain histological pictures. Our findings showed that O. corniculata ME and selenium helped to combat oxidative stress produced by accumulation of AlCl3 in the brain and in prophylaxis against AD. Thus, Selenium (Se) and O. corniculata ME restored antioxidant defense, via enhancing Nrf2/HO-1 hub, hampered neuroinflammation, via TLR4/NF-κβ/NLRP3, along with dampening apoptosis, Aβ generation, tau hyperphosphorylation, BACE1, ApoE4 and LRP1 levels. Treatments also promoted autophagy and modulated Wnt 3/β-catenin/GSK3β cue.

CONCLUSIONS

It was noted that O. corniculata ME showed a notable ameliorative effect compared to Se on Nrf2/HO-1, TLR4/NF-κβ/NLRP3, APOE4/LRP1, Wnt 3/β-catenin/GSK-3β and PERK axes.

HPLC-HESI-MS/MS Analysis of Phenolic Compounds from Cynoglossum tubiflorus Leaf Extracts: An Assessment of Their Cytotoxic, Antioxidant, and Antibacterial Properties

The current study aimed to investigate the chemical composition, antioxidant, antibacterial, and cytotoxic properties of three extracts (hexane, dichloromethane, and methanol) from Cynoglossum tubiflorus. The composition of the methanolic extract was elucidated using HPLC-HESI-MS/MS analysis. The antioxidant effect was examined using NO, DPPH, FRAP, and TAC assays. Antimicrobial activity was evaluated by broth microdilution using various bacterial strains such as S. aureus, S. epidermidis, P. aeruginosa, E. coli, and K. pneumoniae. Structural disruptions in Gram-positive bacteria were visualized using scanning electron microscopy (SEM). Cytotoxic effects were evaluated on human MRC-5 in culture according to the MTT assay. The outcomes suggest that methanol extract contained a high amount of phenolic compounds (254.35 ± 0.360 mg GAE/g DE and 211.59 ± 0.939 mg QE/g DE). By applying the HPLC-HESI-MS/MS analysis, 32 compounds were identified, including phenolic acids, flavonoids, lignans, and fatty acids. This extract showed strong antioxidant (IC50 = 0.043 ± 0.001 mg/mL) and antimicrobial (MIC = 156 µg/mL) activities. The SEM suggests that cells exhibited membrane distortions characterized by surface depressions and alterations in bacterial shape, including dents, when compared to untreated cells. The in vitro cytotoxicity effect on human MRC-5 cells showed no toxicity effects at a concentration of 600 µg/mL. In silico analysis predicted low toxicity for all tested compounds across four different administration routes. This research indicates that this plant could be explored as a powerful source of natural drugs to target pathogens, with applications in the food, pharmaceutical, and medical industries.

A new modified pterocarpan glycoside from Sophora flavescens

Sophora flavescens is a widely used traditional Chinese herbal medicine. In this work, a new pterocarpan glycoside, kurarinol C (1) together with six known compounds, sophoracarpan A (2), trifohrhizin-6'-monoacetate (3), trifohrhizin (4), maackiain (5), (6S,6aS,11aR）-6α-methoxy-pterocarpin (6), L-maackiain (7) were isolated from the roots of S. flavescens. Among them, compounds 2 and 6 were discovered from S. flavescens for the first time. Their chemical structures were elucidated on the basis of extensive NMR and MS analyses. Furthermore, the antioxidant activities of these compounds were evaluated by the ABTS and DPPH free radical scavenging assay. Three compounds (5, 6, 7) exhibited stronger antioxidant capacity against the ABTS enzyme at 20 µg/mL (scavenging rates > 55%).

Protonated Forms of Naringenin and Naringenin Chalcone: Proteiform Bioactive Species Elucidated by IRMPD Spectroscopy, IMS, CID-MS, and Computational Approaches

Naringenin (Nar) and its structural isomer, naringenin chalcone (ChNar), are two natural phytophenols with beneficial health effects belonging to the flavonoids family. A direct discrimination and structural characterization of the protonated forms of Nar and ChNar, delivered into the gas phase by electrospray ionization (ESI), was performed by mass spectrometry-based methods. In this study, we exploit a combination of electrospray ionization coupled to (high-resolution) mass spectrometry (HR-MS), collision-induced dissociation (CID) measurements, IR multiple-photon dissociation (IRMPD) action spectroscopy, density functional theory (DFT) calculations, and ion mobility-mass spectrometry (IMS). While IMS and variable collision-energy CID experiments hardly differentiate the two isomers, IRMPD spectroscopy appears to be an efficient method to distinguish naringenin from its related chalcone. In particular, the spectral range between 1400 and 1700 cm^-1 is highly specific in discriminating between the two protonated isomers. Selected vibrational signatures in the IRMPD spectra have allowed us to identify the nature of the metabolite present in methanolic extracts of commercial tomatoes and grapefruits. Furthermore, comparisons between experimental IRMPD and calculated IR spectra have clarified the geometries adopted by the two protonated isomers, allowing a conformational analysis of the probed species.

Chemical profiling and identification of Radix Cudramiae and their metabolites in rats using an ultra-high-performance liquid chromatography method coupled with time-of-flight tandem mass spectrometry

Radix Cudramiae, known as "Chuan-Po-Shi" in China, is a herbal medicine widely used in the southwest of the country, especially applied by the Miao and Zhuang nationalities for the treatment of liver diseases, such as acute liver injury and liver fibrosis. As a kind of ethnomedicine, the report on its chemical analysis was still blank, which restricted its clinical application. Therefore, this paper aimed to illustrate the chemical characteristics of Radix Cudramiae. A rapid analytical strategy based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was developed to profile the natural small-molecular compounds in Radix Cudramiae, as well as the related prototypes and their metabolites in rats after drug administration. As a result, a total of 74 compounds were detected in the aqueous exact of Radix Cudramiae. In vivo, 45 chemicals including 16 prototypes and 29 metabolites in rat serum, along with 35 chemicals including 17 prototypes and 18 metabolites in rat liver, were screened out and identified. For the first time, the chemical constituents of Radix Cudramiae and their metabolic characteristics were discovered. It was hoped that this work would be beneficial for the safe and effective application of Radix Cudramiae in a clinic.

Characterization of prenylated phenolics in Glycyrrhiza uralensis by offline two-dimensional liquid chromatography/mass spectrometry coupled with mass defect filter

Prenylated phenolics are an important class of natural products. In this study, an efficient strategy was established to systematically characterize the prenylated phenolics in Glycyrrhiza uralensis, a popular herbal medicine. Firstly, offline two-dimensional liquid chromatography/mass spectrometry (2DLC/MS) coupled with mass defect filter (MDF) technology was used to preliminarily detect 1631 potential prenylated phenolics. Secondly, the tandem mass spectrometry fragmentation features of different types of prenylated phenolics were investigated using 29 reference standards. Diagnostic fragmentations included neutral loss (NL) of 42 Da for the annular type and NL of 56 Da for the catenulate type in the positive ion mode, and NL of 56 Da for A-ring prenyl groups and NL of 69 Da for B-ring prenyl groups in the negative ion mode. As a result, the prenylation types, substitution sites, and adjacent OH and OCH₃ substitutions of 320 prenylated phenolics in G. uralensis were rapidly characterized. Moreover, three prenylated dihydrostilbenes were purified from the aerial part of G. uralensis to verify the structural characterizations.

A comprehensive strategy for quality evaluation of Wushe Zhiyang Pills by integrating UPLC-DAD fingerprint and multi-ingredients rapid quantitation with UPLC-MS/MS technology

Wushe Zhiyang Pills (WZP), a classical traditional Chinese medicine (TCM) formula, has been extensively used for the treatment of chronic urticaria and other relevant dermatologic diseases. In this study, a holistic method combining ultra-performance liquid chromatography coupled with diode array detector (UPLC-DAD) fingerprint and multi-components quantitative analysis was developed and validated for quality evaluation of WZP. As a result, a total of 34 characteristic peaks were screened to assess the chemical similarities of 16 batches of WZP samples. By coupling with a hybrid linear ion trap (LTQ)-Orbitrap mass spectrometer, 163 compounds were identified or tentatively identified in WZP. Furthermore, a rapid quantitative analysis method based on ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) technique was optimized and validated for simultaneously determination of 16 chemical markers within 13 min in WZP. The developed UPLC-MS/MS approach was successfully employed for analysis of 16 batches of WZP samples. The proposed comprehensive method combining holistic chemical profile with notable target compounds has proved to be suitable for the systematical quality evaluation of WZP, which provides a feasible and efficient strategy to monitor the overall quality consistency of TCM formulae.

A targeted prenylation analysis by a combination of IT-MS and HR-MS: Identification of prenyl number, configuration, and position in different subclasses of (iso)flavonoids

Prenylated (iso)flavonoids are potent bioactive compounds found in the Fabaceae family. Analysis and quantification of this type of phytochemicals is challenging due to their large structural diversity. In this study, the fragmentation of prenylated (iso)flavonoids was investigated using electrospray ionization ion trap mass spectrometry (ESI-IT-MSⁿ) with fragmentation by collision induced dissociation (CID) in combination and Orbitrap-MS (ESI-FT-MS²) with fragmentation by higher energy C-trap dissociation (HCD). With this combination of IT-MSⁿ and high resolution MS (FT-MSⁿ), it was possible to determine the fragmentation pathways and characteristic spectral features of different subclasses of prenylated (iso)flavonoid standards, as well as characteristic fragmentations and neutral losses of different prenyl configurations. Based on our findings, a decision guideline was developed to (i) identify (iso)flavonoid backbones, (ii) annotate prenyl number, (iii) configuration, and (iv) position of unknown prenylated (iso)flavonoids, in complex plant extracts. In this guideline, structural characteristics were identified based on: (i) UV absorbance of the compound, (ii) mass-to-charge (m/z) ratio of the parent compound; (iii) ratio of relative abundances between neutral losses 42 and 56 u in MSⁿ; (iv) retro-Diels-Alder (RDA) fragments, neutral losses 54 and 68 u, and the ratio [M+H-C₄H₈]⁺/[M+H]⁺. Using this guideline, 196 prenylated (iso)flavonoids were annotated in a Glycyrrhiza glabra root extract. In total, 75 skeletons were single prenylated, 104 were double prenylated, and for merely 17 skeletons prenyl number could not unambiguously be annotated. Our prenylation guideline allows rapid screening for identification of prenylated (iso)flavonoids, including prenyl number, configuration, and position, in complex plant extracts. This guideline supports research on these bioactive compounds in the areas of plant metabolomics and natural products.

"Thermometer" Ions Can Fragment Through an Unexpected Intramolecular Elimination: These Are Not the Fragments You Are Looking For

Benzylpyridinium analogs are effective thermometer ions since monitoring the formation of the benzylium fragment produced from heterolytic cleavage of the C-N bond can be linked to the ion's internal energy. In this study, three para-substituted benzylpyridinium ions containing ethoxy (OEt), isopropoxy (OiPr) and tert-butoxy (OtBu) substitutents were synthesized and evaluated as chemical thermometers. Intriguingly, the product ion spectra of the three benzylpyridinium ions were dominated by m/z 107 instead of the anticipated benzylium species. Deuterium labeling suggested that the m/z 107 fragment resulted from an intramolecular elimination (E_i), which formed via a four-membered transition state (TS). The fragmentation pathway appears to be an anomaly within the mass spectrometry literature, as four-membered pericyclic TSs are usually accompanied by the formation of an exceptionally stable neutral molecule (e.g., CO₂). Quantum-chemical calculations confirmed our hypothesis that stabilization of the strained TS is afforded by hyperconjugation (ΔG^‡ tert-butoxy < isopropyoxy < ethoxy).

Synthesis and Cytotoxic Evaluation of Sanjoseolide and Representative Analogues

The first total synthesis of sanjoseolide (1), which was originally obtained from Dalea frutescens A, was achieved via an efficient route with a longest linear sequence of six steps from the commercially available 2,4-dihydroxyacetophenone in 8.6% overall yield. Meanwhile, a series of sanjoseolide representative analogues were synthesized and assessed for their antiproliferative potency against cancer cells of different origins. Compound 8e inhibited the survival of all tested cancer cell lines in a dose-dependent manner, the IC50 values of the treatment were about 12.8 μM for human cholangiocarcinoma cell lines RBE and 12.7 μM for human cholangiocarcinoma cell lines HCCC-9810, which was more active than sanjoseolide (1). Analysis of the structure-activity relationships revealed that the presence of a trifluoromethyl group may be beneficial in terms of both RBE and HCCC-9810 inhibition.

Phytochemistry and biological properties of isoprenoid flavonoids from Sophora flavescens Ait

Sophora flavescens Ait (Ku-Shen in Chinese) is a popular traditional Chinese herbal medicine in China for a long history. It shows significant pharmacological activities in the treatment of dysentery, eczema, fever, jaundice, vulvar swelling, gastrointestinal hemorrhage and inflammatory disorders. Alkaloids and flavonoids have been identified as virtual components, especially isoprenoid flavanonols are a class of characteristic compounds for S. flavescens. However, few studies have focused on isoprenoid flavonoids analyses and no comprehensive review has yet been published. In the current review, we systematically summarized the isoprenoid flavonoids, a total of 55 compounds have been isolated from S. flavescens, particularly an isoprenyl and a lavandulyl group in backbone structures. Further pharmacological activities, qualitative and quantitative chemical analyses research will contribute to the development of natural isoprenoid flavonoid products in S. flavescens.

UPLC-MS identification and anticomplement activity of the metabolites of Sophora tonkinensis flavonoids treated with human intestinal bacteria

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Total flavonoids of S. tonkinensis showed obvious anticomplement activity after incubated with human intestinal bacteria.

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Eighteen flavonoids were identified from TFST and its metabolites by UPLC-ESI- LTQ/MS.

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Five glycosides were metabolized into three aglycones with more potent anticomplement activity.

Anticomplement activity played an important role in anti-inflammatory effects of traditional Chinese herbs. The total flavonoids of Sophora tonkinensis (TFST) were inactive on the complement system but showed obvious anticomplement activity after incubated with human intestinal bacteria in vitro. In order to discover the metabolic activation of TFST by intestinal flora, the constituents of TFST and its metabolites were identified by UPLC-ESI-LTQ/MS. Their anticomplement activities were evaluated through the classical and alternative pathway. As a result, eighteen flavonoids were identified, including seven flavonoid glycosides, five aglycones and six isoprenylated flavonoids. All the glycosides (daidzein-4′-glucoside-rhamnoside, sophorabioside, rutin, isoquercitrin, quercitrin, ononin, trifolirhizin) were metabolized into their corresponding aglycones in different extent by human intestinal bacteria, resulting in the contents of the five aglycones were highly increased in 24 h. However, no changes have occurred on the six isoprenylated flavonoids. Interestingly, three aglycones (quercetin, formononetin and maackiain) had significantly more potent anticomplement activities than their prototype glycosides. The results indicated that the enhancement of TFST anticomplement activity was attributed to the active aglycones, especially formononetin and quercetin, produced by human intestinal bacteria. These aglycones are likely to be among the potential active components of S. tonkinensis for its inhibiting inflammation effects.

A target-group-change couple with mass defect filtering strategy to identify the metabolites of "Dogel ebs" in rats plasma, urine and bile

"Dogel ebs" was known as Sophora flavescens Ait., a classical traditional Chinese Mongolian herbal medicine, which had the effects on damp-heat dysentery, scrofula, and syndrome of accumulated dampness toxicity. Although the chemical constituents have been clarified by our previous studies, the metabolic transformation of "Dogel ebs" in vivo was still unclear. To explore the mechanism of "Dogel ebs," the metabolites in plasma, bile, and urine samples were investigated. A fast positive and negative ion switching technology was used for the simultaneous determination of flavonoids and alkaloids in "Dogel ebs" in a single run. And a target-group-change coupled with mass defect filtering strategy was utilized to analyze the collected data. 89 parent compounds and 82 metabolites were characterized by high-performance liquid chromatography with quadrupole exactive Orbitrap mass spectrometry. Both phase I and phase II metabolites were observed and the metabolic pathways involved in oxidation, demethylation, acetylation, and glucuronidation. 69 metabolites of "Dogel ebs," including three hydroxyls bonding xanthohumol, formononetin-7-O-glucuronide, 2'-hydroxyl-isoxanthohumol decarboxylation metabolite, oxysophocarpine dehydrogen, 9α-hydroxysophoramine-O-glucuronide, etc. were reported for the first time.

Synthesis and Anti-inflammatory Evaluation of ( R)-, ( S)-, and (±)-Sanjuanolide Isolated from Dalea frutescens

The known chalcone (±)-sanjuanolide (1) can be isolated from Dalea frutescens. This study presents a convergent strategy for the first total synthesis of ( R)-, ( S)-, and (±)-sanjuanolide (1). The key step for synthesizing ( R)- and ( S)-1 was a Corey-Bakshi-Shibata enantioselective carbonyl reduction to construct the C-2″ configuration. ( R)-1 efficiently inhibited the lipopolysaccharides (LPS)-induced expression of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6), while ( S)-1 produced no significant anti-inflammatory effect. ( R)-1 also effectively inhibited the mRNA expression of several inflammatory cytokines after the LPS challenge in vitro. The synthesis and biological properties of these compounds have confirmed ( R)-sanjuanolide and (±)-sanjuanolide as promising new leads for developing anti-inflammatory agents.

Analysis of Active Metabolites of Sophora flavescens for Indoleamine 2,3-dioxygenase and Monoamine Oxidases using Ultra-Performance Liquid Chromatography-Quadrupole time-of-Flight Mass Spectrometry

As part of ongoing research on natural products derived from medicinal plants for enzyme inhibition, known dibenzoyl derivatives (1–3, 11 and 20), pterocarpans (4, 15 and 19), flavanones (5, 7, 10, 12–14, 18, 21–24, 26, 27, 29, 31–33, 35, 36, and 38–46), flavones (6, 16, 28, 30 and 37), isoflavones (8 and 17), furocoumarins (9), and chalcones (25 and 34) have been tentatively identified within fractions of Sophora flavescens roots (SFR) using the ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTof-MS) technique. The extract and column fractions inhibited indoleamine 2,3-dioxygenase (IDO) and monoamine oxidases (MAOs) differently depending on the metabolite groups. The majority of rich fractions were shown to have residual activities of 49–59% at 10 μg/mL (IDO) and 11.7–34.9% at 50 μg/mL (MAOs) or below. In the total ion current (TIC) chromatogram, significant markers for the metabolites of the bioactive-guided fractions were identified; pterocarpans (4, 15 and 19), flavanones (5, 10, 12–14, 18, 21–23, 26, 29 31–33, 35, 36, and 38–46), isoflavones (8 and 17), furocoumarins (9), dibenzoyl derivatives (11 and 20), flavones (16, 28, 30 and 37), and chalcones (25 and 34) were evaluated among forty-six analyzed metabolites. Possible bioactive markers could be deduced using a data library and previous references, and information regarding spectroscopic characterization and optimal target metabolites was obtained.

Use of an UHPLC-MS/MS Method for Determination of Kuraridin and Characterization of Its Metabolites in Rat Plasma after Oral Administration

Kuraridin is an active natural prenylated flavonoid ingredient originating from the well-known traditional Chinese medicine Sophora flavescens Ait., that possesses various bioactivities, such as antitumor activity, PLC_γ1 inhibitory activity, glycosidase inhibitory activity, etc. However, there is no report on the plasma metabolic profile and pharmacokinetic study of kuraridin. The current study was designed to use an ultra-performance liquid chromatography/tandem mass spectrometry (UHPLC-MS/MS) method for the quantification and characterization metabolites in rat plasma after oral administration of kuraridin. A liquid-liquid extraction method with ethyl acetate-acetonitrile (1:3) was used to extract the kuraridin from rat plasma samples. The chromatographic separation was carried out on a Hypersil GOLD UHPLC C18 column equipped with a C18 guard cartridge using a gradient elution with organic solvent-water as mobile phase. Based on comparing the retention times with reference standards or on the basis of MS₂ fragmentation behaviors, a total of 19 metabolites were identified or tentatively characterized from rat plasma. Under the optimized conditions, the method showed good linearity (r² > 0.99) over the ranges of 1–500 ng/mL for kuraridin. The inter- and intra-day precisions were less than 8.95%, and the accuracy was in the range of −6.27–6.48%. The recovery of kuraridin ranged from 90.1% to 100.4%. The developed UHPLC-MS/MS method was thus successfully applied in the qualitative of metabolites and quantitative analysis of kuraridin in rat plasma.

Selective Extraction of Flavonoids from Sophora flavescens Ait. by Mechanochemistry

Flavonoids from Sophora flavescens were selectively extracted by mechanochemical-promoted extraction technology (MPET) after using response surface methodology to determine the optimal extraction parameters. The highest yield of 35.17 mg/g was achieved by grinding the roots with Na₂CO₃ (15%) at 440 rpm/min for 17.0 min and water was used as the sole solvent with a ratio of solvent to solid material of 25 mL/g. Flavonoids prepared by MPET demonstrated relatively higher antioxidant activities in subsequent DPPH and hydroxyl radical scavenging assays. Main constituents in the extracts, including kurarinol, kushenol I/N and kurarinone, were characterized by HPLC-MS/MS, indicating good selective extraction by MPET. Physicochemical property changes of powder during mechanochemical milling were identified by scanning electron microscopy, X-ray powder diffraction, and UV-Vis diffuse-reflectance spectroscopy. Compared with traditional extraction methods, MPET possesses notable advantages of higher selectivity, lower extraction temperature, shorter extraction time, and organic solvent free properties.

Fragmentation reactions using electrospray ionization mass spectrometry: an important tool for the structural elucidation and characterization of synthetic and natural products

Over the last decade, the number of studies reporting the use of electrospray ionization mass spectrometry (ESI-MS) in combination with collision cells (or other activation methods) to promote fragmentation of synthetic and natural products for structural elucidation purposes has considerably increased. However, the lack of a systematic compilation of the gas-phase fragmentation reactions subjected to ESI-MS/MS conditions still represents a challenge and has led to many misunderstood results in the literature. This review article exploits the most common fragmentation reactions for ions generated by ESI in positive and negative modes using collision cells in an effort to stimulate the use of this technique by non-specialists, undergraduate students and researchers in related areas.

Erythrina excelsa exhibits estrogenic effects in vivo and in vitro and is cytotoxic on breast and colon cancer cell lines

CONTEXT

Eythrina excelsa Baker (Fabaceae) is a medicinal plant used to treat various ailments including those of the female genital tract.

OBJECTIVE

The objective of this study is to investigate the estrogenic and cytotoxic effects of the ethanol extract of the stem bark of E. excelsa.

MATERIALS AND METHODS

Erythrina excelsa was evaluated in vitro using the yeast estrogen screen (YES). The extract was then tested in a 3-day uterotrophic assay on ovariectomised Wistar rats at doses of 50 and 100 mg/kg BW/d. Cytotoxic effects were assessed on breast (MCF-7) and colon (HT-29) cancer cell lines using the MTT cell viability assay. Additionally, a LC-PDA-ESI (+)-HRMS and HRMS/MS method was developed and applied for the identification of representative secondary metabolites scaffolds in the extract.

RESULTS

In the YES, the extract stimulated the transactivation of the estrogen receptor in a dose-dependent manner with an EC50 value of 1.8 μg/mL. In rats, E. excelsa increased uterine wet weight, uterine epithelial height, and the mRNA expression of estrogen-responsive genes in the uterus and liver at 50 whereas at 100 mg/kg BW/d anti-estrogenic effects were observed. In the MTT-assay, a dose-dependent decrease of the viability of both cell lines was observed with EC50 values of 13.6 μg/mL (MCF-7) and 27.7 μg/mL (HT-29). The phytochemical analysis revealed that the extract is rich in isoflavonoids, mainly prenylated and pyran-derivatives thereof.

CONCLUSION

Erythrina excelsa is rich in prenylated and pyran-substituted isoflavonoids, exhibits estrogenic/anti-estrogenic and cytotoxic effects and warrant sufficient interest for deeper investigations.

Oxymatrine induces apoptosis in human cervical cancer cells through guanine nucleotide depletion

Oxymatrine is an alkaloid obtained primarily from Sophora roots and has been shown to show anticancer effects in various cancers. However, the cellular and molecular effects of this agent on cervical cancer have been poorly characterized. Here, we investigated the antitumor effect of oxymatrine on a human cervical cancer cell line (HeLa). Our results showed that application of oxymatrine significantly inhibited the cell growth and tumorigenesis in a dose-dependent manner and induced apoptosis through caspase-dependent pathways as determined using flow cytometry and TUNEL staining analysis. To define the proteins potentially related to the mechanisms of action, proteomic analysis was utilized to detect proteins altered by oxymatrine. As the downregulated gene, inosine monophosphate dehydrogenase type II (IMPDH2) was responsible for oxymatrine-induced mitochondrial-related apoptosis. Moreover, oxymatrine depleted intracellular guanosine 5'-triphosphate (GTP) levels by effective IMPDH inhibition. Functional analyses further showed that oxymatrine and tiazofurin, an inhibitor of IMPDH2, sensitized resistant HeLa/DDP cells to cisplatin. In addition, the expression of IMPDH2 in cervical cancer was significantly higher than that in the normal cervical epithelium. Taken together, these findings suggest that targeting of IMPDH2 by potential pharmacological inhibitors, oxymatrine in combination with chemotherapy, might be a promising means of overcoming chemoresistance in cervical cancer with high IMPDH2 expression, and may thus provide new insights into the mechanism of oxyamtrine-induced anticancer effects.

Characterisation of homoflavonoids from three Ophioglossum species using liquid chromatography with diode array detection and electrospray ionisation tandem mass spectrometry

INTRODUCTION

Homoflavonoids, characterised by one more carbon atom directly added to C6 -C3 -C6 backbone of flavonoids, are rich in the species of genus Ophioglossum. Up to now we have little knowledge about their MS fragmentation patterns. It is therefore necessary to investigate their MS fragmentation pathways so as to distinguish them from other types of flavonoids.

OBJECTIVE

To develop a rapid method for identifying homoflavonoids from Ophioglossum based on their characteristic MS fragmentation.

METHODS

Mass spectrometry fragmentation pathways and qualitative analysis of homoflavonoids in three ferns of Ophioglosssum were investigated by using high-performance liquid chromatography coupled with diode-array detection and electrospray ionisation tandem mass spectrometry (HPLC-DAD-ESI/MS(n) ).

RESULTS

The analyses of the MS(n) spectra of the homoflavonoids allowed us to classify them into two types according to their fragmentation characteristics. The type I homoflavonoids, with an attached additional carbon atom to the C-3 position of the C-ring, presented the initial competing loss of H2 O and CH2 O from their aglycone ions, compared to the initial removal of H2 O or CO in the case of the type II homoflavonoids, which bear the additional carbon atom at the C-2' site of the B-ring and forming ring D. The above characteristic fragmentations of homoflavonoids were quite different from those of other flavonoids, and were successfully applied to identify homoflavonoids in the crude extracts of three Ophioglossum species.

CONCLUSION

The HPLC-DAD-ESI/MS(n) method obtained in the present study provided a powerful tool for identifying homoflavonoids from ferns in the genus Ophioglossum.

Collision-induced dissociation of 40 flavonoid aglycones and differentiation of the common flavonoid subtypes using electrospray ionization ion-trap tandem mass spectrometry and quadrupole time-of-flight mass spectrometry

Much Literature is available with respect to the collision-induced dissociation (CID) of different subtypes of flavonoid aglycones. However, a simultaneous comparison study of the common flavonoid subtypes under unified conditions is rarely reported, which is of crucial significance for their rapid structural elucidation. This study depicted the negative CID of 40 free flavonoids (comprising nine different subtypes) utilizing electrospray ionization ion-trap tandem mass spectrometry (ESI-IT-MSn). High-accuracy quadrupole time-of-flight mass spectrometry was employed to confirm the chemical formula of proposed key fragments. Specific fragmentation features were discovered among different flavonoid subtypes in terms of the essential collision energy, base peak, RDA fragmentation, and diversity of fragmentation pathways: CID of flavanones, chalcones and flavanonols was in need of lower Levels of collision energy [<40%) and exhibited simplified fragmentation pathways; overriding neutral loss of CO2 was detected for flavones, aurones and xanthones, while isoflavones preferred neutral loss of CO; 1,2A- and 1,3A- fragments were respectively dominant for flavonols and flavanones/chalcones, white homoisoflavones underwent specific radical elimination of ring B or methylene-ring B. These differentiated fragmentation characteristics integrating UV absorption resulted in the establishment of a decision tree to characterize and distinguish the common flavonoid subtypes. This study firstly revealed remarkable differentiations in the negative CID behavior of nine common flavonoid aglycone subtypes and the proposed determination strategy would much benefit the screening and rapid characterization of flavonoids from complicated matrixes by tandem mass spectrometry.

Effects of matrine on proliferation and apoptosis of cultured retinoblastoma cells

BACKGROUND

Extracted from the traditional Chinese medicine of Kushen, matrine is an alkaloid with potential anti-neoplastic and anti-inflammatory effects. Here, we examined the effect of matrine on proliferation and apoptosis of cultured retinoblastoma cells.

METHODS

The retinoblastoma cell lines Y79, WERI-RB1 and SO-RB50 were treated with matrine in increasing concentrations from 0.2-1.1 mg/ml for 24 hours, and the cell proliferation rate was measured. The cells were exposed to matrine at 50% inhibition concentration (IC50) for 12, 24 and 48 hours. Cell cycle was analyzed by flow cytometry, concentration of proteins regulating cell cycle and apoptosis was determined by Western blot, apoptosis rate was measured by TUNEL staining, and cell morphology was assessed by electron transmission microscopy.

RESULTS

The retinoblastoma cell lines Y79, WERI-RB1 and SO-RB50 showed an increased inhibition of cell proliferation with increasing matrine concentrations. Applying the IC50 concentration of matrine, the alteration of the cell cycle, including a reduced percentage of the S phase, was significantly (P < 0.01) associated with a longer treatment time by matrine. Correspondingly, the cell-cycle-associated proteins P21 and P27 were up-regulated and the protein cyclinD1 was down-regulated. The apoptosis-associated protein Bcl-2 was down-regulated, and Bax was up-regulated. In a similar manner, the apoptosis rate was significantly increased with longer treatment time.

CONCLUSIONS

Matrine added to cultures of immortalized retinoblastoma cells led to a reduced tumor cell proliferation, decreased rate of mitosis and an increased tumor cell apoptosis, paralleled by corresponding changes in the proteins regulating the cell cycle or apoptosis.

Characterization of alkaloids in Sophora flavescens Ait. by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry

Sophora flavescens Ait., a well-known Chinese herbal medicine, is widely used in clinical practice for the treatment of viral hepatitis, cancer, gastrointestinal hemorrhage, and skin diseases. This paper is the first report on a method based on the combined use of high-performance liquid chromatography, photodiode array detection, and electrospray ionization tandem mass spectrometry for the comprehensive and systematic separation and characterization of bioactive alkaloids in Sophora flavescens Ait. A total of 22 constituents were identified on the basis of the extracted ion chromatograms for different [M+H](+) ions of the alkaloids present in S. flavescens Ait. Among these, 5 constituents were unambiguously identified by comparing the experimental data on their retention times and MS(n) spectra with those of the authentic compounds, and 17 other constituents were tentatively identified on the basis of their MS(n) fragmentation behaviors and/or molecular weight information from literatures. Furthermore, some characteristic fragmentation pathways of the alkaloids in S. flavescens Ait. were detected and examined. This information may be useful for characterizing the bioactive alkaloids present in S. flavescens Ait. and for possible applications in formulations.

The flavonoid-rich fraction of Coreopsis tinctoria promotes glucose tolerance regain through pancreatic function recovery in streptozotocin-induced glucose-intolerant rats

AIM OF THE STUDY

Infusions of Coreopsis tinctoria Nutt. flowering tops have been used traditionally in Portugal to control hyperglycaemia and a previous study revealed that daily administration of the infusion during a 3-week period promoted the recovery of glucose tolerance by a mechanism different from inhibition of glucose absorption and direct promotion of insulin secretion. We know report the study of the ethyl acetate fraction of Coreopsis tinctoria flowers infusion aiming to confirm flavonoids as bioactive metabolites. To give one step forward into the antihyperglycaemic mechanism of action of this traditionally used plant we also studied the activity of Coreopsis tinctoria flavonoids on the pancreatic function of glucose-intolerant rats. A standard antioxidant, Trolox, was also studied for comparative purposes as the antioxidant mechanism has been frequently purposed as one of the mechanisms mediating antihyperglycaemic effects of flavonoid-rich extracts.

MATERIAL AND METHODS

Thirteen compounds, mainly of flavanone and chalcone flavonoidal type, have been identified in this fraction by HPLC-DAD-ESI-MS/MS, and the major one (marein) quantified by HPLC-UV. The fraction (125 mg containing 20 mg of marein/kg b.w.) and Trolox (50 mg/kg b.w.) were administered daily by oral gavage to normal and STZ (40 mg/kg b.w.)-induced glucose-intolerant Wistar rats for 3 weeks. Blood glucose levels were measured weekly by Oral Glucose Tolerance Test. Pancreatic function was evaluated by plasma lipase of treated and non-treated glucose-tolerant and- intolerant rats after the 3-week treatment period.

RESULTS

After 2 weeks oral treatment with Coreopsis tinctoria AcOEt fraction the animals were no longer glucose-intolerant, an effect maintained over the remaining experimental period. Additionally, plasma lipase values of glucose-intolerant animals treated with the AcOEt fraction (13.5 ± 0.84 U/L) showed a clear reduction when compared with the glucose-intolerant group (34.60 ± 1.76 U/L; P<0.001) and normoglycaemic control (8.35 ± 0.69 U/L) demonstrating recovery of pancreatic function. On the other hand, treatment with standard antioxidant Trolox had no effect on glucose homeostasis of glucose-intolerant rats. The oral treatment with Coreopsis tinctoria fraction caused no hepatotoxicity, as determined by blood alanine and aspartate transaminases, and had also no effect on glucose homeostasis and pancreatic function of normal rats.

CONCLUSIONS

AcOEt fraction, containing the same amount of marein as the infusion, promoted glucose tolerance regain in the rats more quickly, which means that the bioactivity is probably due to the several flavonoids present in Coreopsis tinctoria extracts and not to marein alone. The results also strongly suggest that these compounds act by promoting pancreatic cell function recovery from STZ-induced injury, possibly through a mechanism of action other than merely antioxidant mediated.

A rapid screening method for prenylated flavonoids with ultra-high-performance liquid chromatography/electrospray ionisation mass spectrometry in licorice root extracts

Due to their substitution with an isoprenoid group, prenylated flavonoids have an increased affinity for biological membranes and target proteins, enhancing their potential bioactivity. Although many prenylated flavonoids have been described, there are no methods that specifically screen for their presence in complex mixtures, prior to purification. We describe a method based on ultra-high-performance liquid chromatography (UHPLC) with electrospray ionisation mass spectrometry (ESI-MS) that allows rapid screening for prenylated flavonoids in multi-component plant extracts. Identification of the prenylated flavonoids is based on screening for neutral losses of 42 u and 56 u in the positive-ion mode MS(2) and MS(3) spectra within the MS chromatograms. In addition, this method discriminates between a prenyl chain and a ring-closed prenyl (pyran ring), based on the ratio of the relative abundances of the ions that lose 42 u and 56 u (42:56). The application of this screening method on a 70% aq. ethanol, ethanol and ethyl acetate extract of the roots of Glycyrrhiza glabra indicated the presence of 70 mono- and di-prenylated flavonoids. In addition, of each prenylated flavonoid the type of prenylation, chain or pyran ring was determined.