Rapid recognition and targeted isolation of potential anti-breast cancer xanthones in Hypericum bellum Li by "seed" mass spectra-based molecular networking and in silico MS/MS fragmentation.

INSTRUCTION: Hypericum bellum Li is rich in xanthones with various bioactivities, especially in anti-breast cancer. While the scarcity of mass spectral data of xanthones in Global Natural Products Social Molecular Networking (GNPS) libraries have challenged the rapid recognition of xanthones with similar structures. OBJECTIVE: This study is aimed to enhance the molecular networking (MN)-based dereplication and visualisation ability of potential anti-breast cancer xanthones from H. bellum to overcome the scarcity of xanthones mass spectral data in GNPS libraries. Separating and purifying the MN-screening bioactive xanthones to verify the practicality and accuracy of this rapid recognition strategy. METHODOLOGY: A combined strategy of "seed" mass spectra-based MN, in silico annotation tools, substructure identification tools, reverse molecular docking, ADMET screening, molecular dynamics (MDs) simulation experiments, and an MN-oriented separation procedure was first introduced to facilitate the rapid recognition and targeted isolation of potential anti-breast cancer xanthones in H. bellum. RESULTS: A total of 41 xanthones could only be tentatively identified. Among them, eight xanthones were screened to have potential anti-breast cancer activities, and six xanthones that were initially reported in H. bellum were obtained and verified to have good binding abilities with their paired targets. CONCLUSION: This is a successful case study that validated the application of "seed" mass spectral data could overcome the drawbacks of GNPS libraries with limited mass spectra and enhance the accuracy and visualisation of natural products (NPs) dereplication, and this rapid recognition and targeted isolation strategy can be also applicable for other types of NPs.

Development and optimization of a method based on dispersive solid phase extraction followed by ultra-high-performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry for simultaneous determination of 30 mycotoxins in Citrus products.

Citrus, a raw material widely used in food and medicine, is susceptible to fungal infection and its metabolites during growth, transportation, and storage. Thus, monitoring the residual levels of various mycotoxins in Citrus traditional Chinese medicines and related products is crucial. This study described a simple, reliable, and sensitive method for simultaneous identification and quantification of 30 mycotoxins in Citrus products. The method is based on modified quick, easy, cheap, effective, rugged, and safe extraction and purification followed by ultra-high-performance liquid chromatography-quadrupole/orbitrap high-resolution mass spectrometry. The limit of detection ranged from 0.10 to 1.50 µg/kg, and the quantification ranged from 0.25 to 5.00 µg/kg. The recoveries at three spiked levels were 64.90-99.72% and the relative standard deviation was less than 12%. The method was applied to 55 Citrus samples. The detection rates of tentoxin and mycophenolic acid were the highest, reaching 22.7% and with concentration ranges of 0.33-1.03 and 0.57-2.09 µg/kg, respectively. All contamination levels were below the maximum residue limits recommended by the European Commission and China. These results could be used to establish guidelines for screening mycotoxins in Citrus products and the limits of acceptable levels.

[Simultaneous determination of monosaccharides and oligosaccharides in Lycium barbarum L. by high performance liquid chromatography].

OBJECTIVE: To develop a rapid approach of refractive index detection with high performance liquid chromatography (HPLC) for the determination of rhamnose, fructose, glucose, surose and maltose in Lycium barbarum L. METHODS: The sample was extracted with water and the analyte was separated by Zorbax Carbohydrate column with acetonitrile-water as mobile phase. RESULTS: Good linear correlations between the concentrations and the peak areas of the analyte were found, with the correlation coefficients ranging from 0.9976 to 0.9998. The spiked recovery rates ranged from 92.27% to 101.93%, with 1.85%-3.27% of relative standard deviations (n=5). The limits of detection (S/N =3) were 4-6 mg/kg. CONCLUSION: The proposed method is suitable for the determination of monosaccharide and oligosaccharide in Lycium barbarum L.

High-performance liquid chromatographic analysis of bisphenol A and 4-nonylphenol in serum, liver and testis tissues after oral administration to rats and its application to toxicokinetic study.

A sensitive and simple method based on solid-phase extraction (SPE) and HPLC with fluorescence detection for the determination of bisphenol A (BPA) and 4-nonylphenol (4-NP) in rat serum, liver and testis tissues has been developed. The chromatographic conditions consisted of a C18 column and mobile phase composition of acetonitrile and water with flow rate of 1.0 ml/min. The fluorescence detection was performed at excitation and emission wavelengths of 227 nm and 313 nm, respectively. Under these conditions, BPA and 4-NP were well separated and showed good linearities in the ranges of 0.01-50.0 microg/ml for BPA and 0.15-150.0 microg/ml for 4-NP with correlation coefficients greater than 0.999. The detection limits of serum and tissue samples were 2.8 ng/ml and 1.4 ng/g for BPA and 5.6 ng/ml and 2.8 ng/g for 4-NP at a signal-to-noise ratio (S/N) of 3. The intra-assay and the inter-assay precisions were better than 11.4%. Recoveries of BPA and 4-NP were 78.6-95.0% and 80.2-93.4%, respectively. The proposed method was applied to a toxicokinetic study of BPA and 4-NP including individual and combined oral administration to rats. The results showed that 4-NP remarkably altered the toxicokinetic parameters of BPA in testis, while parameters of BPA were not obviously altered in serum and liver under the experimental conditions investigated. On the other hand, there was no significant difference in the toxicokinetics of 4-NP when administered with BPA.

Rapid measurement of free cyanide in liquor by ion chromatography with pulsed amperometric detection.

This study investigated the measurement of free cyanide in liquor by ion chromatography coupled with pulsed amperometric detection (IC-PAD). Eluent concentration, interferent evaluation and method performance were discussed. Results show that free cyanide in liquor can be rapidly determined by the optimised IC-PAD method. A sample requires only 1:100 dilution and simple filtration before being subjected to IC-PAD. The linear range is 1-5000 µg/L with an R value of 0.9998. The detection limit is 1 µg/L for a 25 µL injection loop. The overall relative standard deviation (RSD) of the method is less than 5%, and the recovery range is from 98.1% to 105.0%. This study has been proven significant and may have potential applications in liquors analysis.

[Determination of 4-nonylphenol and bisphenol A in rat serum by high performance liquid chromatography with fluorescence detection].

OBJECTIVE: This study was directed to the development of a simple and highly sensitive method for determination of 4-nonylphenol (4-NP) and bisphenol A (BPA) in rat serum using HPLC with fluorescence detector. METHODS: 4-NP and BPA in serum samples were extracted by a mixed solvent of n-hexane and diethyl ether (70:30), the organic layer was dried with nitrogen flow and dissolved with mobile phase. The operating conditions such as C18 column (250 mm x 4.6 mm, 5 microns), acetonitrile-ammonium acetate buffer (pH 4.5) as mobile phase at a flow rate of 1 ml/min and fluorescence detector with the excitation and emission wavelength at 227 nm and 313 nm respectively were used for the determination. RESULTS: There was good linear relationship between the concentrations of the analytes in rat serum and their peak areas in the ranges of 0.013-5.0 micrograms/ml for 4-NP and 0.004-3.0 micrograms/ml for BPA. The detection limit of the method was 13 ng/ml for 4-NP and 4 ng/ml for BPA. Recoveries of rat serum samples were 83.8%-100.0% for 4-NP and 83.3%-100.0% for BPA. The intra-day precision was 1.70%-2.70%, the inter-day precision was 2.06%-9.78%. CONCLUSION: The results showed that the method is suitable for the determination of BPA and 4-NP in serum.

[Simultaneous determination of three estrogens in feed by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry].

A method was developed for the simultaneous determination of three estrogens (17ß-estradiol, estradiol benzoate, estradiol valerate) in feed by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). After the sample was extracted by acetonitrile and cleaned-up on a Heaion C18 solid phase extraction (SPE) column, the three estrogens were separated by an ACQUITY UPLC BEH C18 column (50 mm x 2.1 mm, 1.7 µm) with gradient elution using acetonitrile and 0.1% ammonia solution as mobile phases and finally confirmed and quantified in multiple reaction monitoring (MRM) mode. The internal standard calibration curves were used for the quantification. The results showed that all the estrogens were determined with excellent linear relationships from 10 µg/L to 200 µg/L for 17ß-estradiol and estradiol valerate, and from 5 µg/L to 200 µg/L for estradiol benzoate. The correlation coefficients (r) of the three estrogens were not lower than 0. 996. The limits of detection for 17ß-estradiol, estradiol benzoate and estradiol valerate were 7 µg/kg, 5 µg/kg and 7 µg/kg, respectively. The average recoveries were 96.5%-102.0%. The results demonstrated that the developed method can simultaneously determine the three estro- gens in feed with advantages of simple pretreatment, rapid analysis, low limit of detection and high accuracy.

[Determination of bisphenol A and 4-nonylphenol in rat tissues by high performance liquid chromatography with fluorescence detection].

A simple and highly sensitive method has been developed for the determination of bisphenol A (BPA) and 4-nonylphenol (4-NP) in rat tissues by high performance liquid chromatography (HPLC) with fluorescence detection. The rat tissue samples were homogenized-with methanol-ammonium acetate buffer (2:8, v/v) by a high-speed homogenizer and then BPA and 4-NP were extracted by a mixed solvent of n-hexane and diethyl ether (7:3, v/v). The organic layer was evaporated with a stream of nitrogen, and the residue was dissolved in the mobile phase. The chromatographic operating conditions were a C18 column (250 mm x 4. 6 mm i.d., 5 microm), acetonitrile-ammonium acetate buffer (pH 4.5) (75:25, v/v) as mobile phase at a flow rate of 1 mL/min, fluorescence detection with the excitation and emission wavelengths at 227 nm and 313 nm, respectively. Average recoveries for rat tissues at three different levels were in the range of 82.0% -95.4% for BPA and 81.2% -96.5% for 4-NP. The relative standard deviations (RSDs) were 0. 37% - 5.28% and the detection limits were 4.0, 4.6, 3.2, 3.3 ng/g for BPA and 12.0, 15.6, 11.8, 13.8 ng/g for 4-NP in liver, kidney, heart and brain tissues, respectively. The intra-day precisions were 0.89% -4.50%, and the inter-day precisions were 3.10% - 12.40%. These results demonstrated that the proposed method is simple, sensitive, and reliable for the determination of BPA and 4-NP in animal tissues.