Jiaoyang Luo

UFLC-ESI-MS/MS analysis of multiple mycotoxins in medicinal and edible Areca catechu

A robust, sensitive and reliable ultra fast liquid chromatography combined with electrospray ionization tandem mass spectrometry (UFLC-ESI-MS/MS) was optimized and validated for simultaneous identification and quantification of eleven mycotoxins in medicinal and edible Areca catechu, based on one-step extraction without any further clean-up. Separation and quantification were performed in both positive and negative modes under multiple reaction monitoring (MRM) in a single run with zearalanone (ZAN) as internal standard. The chromatographic conditions and MS/MS parameters were carefully optimized. Matrix-matched calibration was recommended to reduce matrix effects and improve accuracy, showing good linearity within wide concentration ranges. Limits of quantification (LOQ) were lower than 50 μg kg(-1), while limits of detection (LOD) were in the range of 0.1-20 μg kg(-1). The accuracy of the developed method was validated for recoveries, ranging from 85% to 115% with relative standard deviation (RSD) ≤14.87% at low level, from 75% to 119% with RSD ≤ 14.43% at medium level and from 61% to 120% with RSD ≤ 13.18% at high level, respectively. Finally, the developed multi-mycotoxin method was applied for screening of these mycotoxins in 24 commercial samples. Only aflatoxin B2 and zearalenone were found in 2 samples. This is the first report on the application of UFLC-ESI(+/-)-MS/MS for multi-class mycotoxins in A. catechu. The developed method with many advantages of simple pretreatment, rapid determination and high sensitivity is a proposed candidate for large-scale detection and quantification of multiple mycotoxins in other complex matrixes.

A targeted agent with intercalation structure for cancer near-infrared imaging and photothermal therapy

A new targeted photothermal agent used in cancer photothermal therapy (PTT) is synthesized by co-intercalation of indocyanine green (ICG) and targeting folic acid (FA) into the interlamellar gallery of layered double hydroxide (LDH). The resulting composite material (ICG–FA/LDH) possesses an interlayer distance of 2.503 nm, and a uniform particle size with an equivalent hydrodynamic diameter of 127 nm. ICG presents a monomeric state in the LDH gallery, owing to the supermolecular interactions between the LDH host and ICG guest, which results in a largely-enhanced photothermal conversion efficiency. In vitro tests performed with KB cells demonstrate a highly enhanced cellar uptake and excellent imaging ability for the ICG–FA/LDH. The photothermal conversion studies show that an ultra-low dosage of ICG–FA/LDH (equivalent ICG 10 μg mL−1) under weak near-infrared (NIR) irradiation (8 min; 1.1 W cm−2) achieves a significant temperature increase from 19.8 °C to 51.0 °C. Therefore, a satisfactory in vitro PTT effectiveness of the ICG–FA/LDH composite is obtained, and it exhibits cellular damage as high as 87.4% with an ultra-low dosage of ICG (8 μg mL−1) and weak NIR irradiation (1.1 W cm−2, 12 min). In addition, the photothermal agent ICG–FA/LDH displays good targeting capability, biocompatibility and low cytotoxicity. It is expected that the unique ICG–FA/LDH with integrated fluorescence imaging and photothermal therapy can be potentially used in the cell labeling and PTT area.

An indirect competitive fluorescence assay for ochratoxin A based on molecular beacon

A novel, simple and efficient method based on a molecular beacon (MB) probe was developed to detect ochratoxin A (OTA) in malts, which is a common starting material in the brewery industry. With the critical site for OTA binding in capture aptamer in mind, a MB probe containing 20 bases with a fluorophore–quencher pair at the stem ends was designed and synthesized. In the “off” configuration, the fluorescein (FAM) is internally quenched due to close contact with dabcyl and the fluorescence signal is recovered after hybridization with the capture aptamer at the “on” state. In the presence of OTA, the MB probe competes for binding at the loop region of the aptamer, resulting in a decrease in fluorescence signal. Using this indirect competitive assay, the detection of OTA in malt samples was accomplished for the first time. In addition, the effect of binding affinity of the capture aptamer and OTA on the assay performance was investigated. Under optimal conditions, this method allowed for OTA detection at a linear range of 0.0001–1 μg mL−1 (correlation coefficient, R = 0.9920) with superior sensitivity and a detection limit as low as 0.05 ng mL−1. The sensing system also displayed an excellent selectivity and perfect anti-interference capacity in the matrix. Moreover, the entire process of detection was accomplished in less than 20 min. The recovery from spiked malt samples ranged from 81.0% to 95.2% with RSDs below 5.4%. The performance of our method was further validated by ultra-fast liquid chromatography coupled with tandem mass spectrometry. Compared with similar fluorescence assays, the proposed method is simple, efficient and does not require complicated conjugation steps. Taken together, this novel detection strategy could be a promising tool for hand-held devices used during on-site monitoring of contaminants.

Determination and pharmacokinetic properties of arsenic speciation in Xiao-Er-Zhi-Bao-Wan by high-performance liquid chromatography with inductively coupled plasma mass spectrometry.

A method of high performance liquid chromatography with a Hamilton PRP-X100 ion-exchange column (250 × 4.1 mm id, 10 μm) coupled to inductively coupled plasma mass spectrometry was employed to generate a full concentration-time profile of arsenic speciation after oral administration. The results exhibited good linearity and revealed that, in the pills, the average arsenic concentration was 10105.4 ± 380.7 mg/kg, and in the water extraction solution, the inorganic As(III) and As(V) concentrations were 220.1 ± 12.6 and 45.5 ± 2.3 mg/kg, respectively. No trace of monomethyl arsenic acid was detected in any of the plasma samples. We then successfully applied the established methodology to examine the pharmacokinetics of arsenic speciation. The resulting data revealed that, after oral administration in rats, the plasma concentration of each arsenic species reached Cmax shortly after initial dosing, and that the distribution and elimination of As(V) was faster than that of As(III) and dimethyl arsenic acid. Additionally, the t1/2 values of As(V), As(III), and dimethyl arsenic acid were 3.4 ± 1.6, 14.3 ± 4.0, and 19.9 ± 1.6 h, respectively. This study provides references for the determination of arsenic speciation in mineral-containing medicines and could serve as a useful tool in measuring the true toxicity in traditional medicines that contain them.

Quantitative and fingerprinting analysis of Atractylodes rhizome based on gas chromatography with flame ionization detection combined with chemometrics.

This study assessed the feasibility of gas chromatography with flame ionization detection fingerprinting combined with chemometrics for quality analysis of Atractylodes rhizome. We extracted essential oils from 20 Atractylodes lancea and Atractylodes koreana samples by hydrodistillation. The variation in extraction yields (1.33-4.06%) suggested that contents of the essential oils differed between species. The volatile components (atractylon, atractydin, and atractylenolide I, II, and III) were quantified by gas chromatography with flame ionization detection and confirmed by gas chromatography with mass spectrometry, and the results demonstrated that the number and content of volatile components differed between A. lancea and A. koreana. We then calculated the relative peak areas of common components and similarities of samples by comparing the chromatograms of A. lancea and A. koreana extracts. Also, we employed several chemometric techniques, including similarity analysis, hierarchical clustering analysis, principal component analysis, and partial least-squares discriminate analysis, to analyze the samples. Results were consistent across analytical methods and showed that samples could be separated according to species. Five volatile components in the essential oils were quantified to further validate the results of the multivariate statistical analysis. The method is simple, stable, accurate, and reproducible. Our results provide a foundation for quality control analysis of A. lancea and A. koreana.

Enhancement effect of essential oils from the fruits and leaves of Alpinia oxyphylla on skin permeation and deposition of indomethacin

Essential oils from plants are gaining increasing attention as potential chemical penetration enhancers. This study aimed to investigate the enhancement effect of essential oils from the fruits and leaves of Alpinia oxyphylla on skin permeation and deposition of indomethacin. In vitro permeation experiments were performed in Franz-type cells through rat skin, and the amount of drug passing through into the receptor phase was analyzed by ultra performance liquid chromatography-photodiode array (UPLC-PDA). Ultra fast liquid chromatography coupled with tandem mass spectrometry (UFLC-MS/MS) was used to analyze the plasma drug concentration of indomethacin to examine the enhancement effect of essential oils in an in vivo rat model of drug delivery. Both oils demonstrated a significant enhancement effect on drug delivery and skin deposition (p < 0.05). Particularly, at 3% concentration, enhancement ratios of fruit oil and leaf oil were 10.16 and 4.61, respectively, which were both significantly higher than that of the commonly used enhancer, Azone (2.04). Major constituents of both oils were identified by gas chromatography-mass spectrometry (GC-MS). It may be deduced that higher content hydrocarbon terpenes in the fruit oil contribute to the increased enhancement effect relative to leaf oil. The skin irritation test indicated that both oils at certain concentrations (1%, 3%, and 5%) did not cause obvious erythema or edema in rabbits. Considering their enhanced drug permeation and low skin irritation, essential oils from Alpinia oxyphylla could be novel penetration enhancers and have promising applications in transdermal drug delivery and cosmetics.

Accumulation of Arsenic Speciation and In Vivo Toxicity Following Oral Administration of a Chinese Patent Medicine Xiao-Er-Zhi-Bao-Wan in Rats

Realgar-containing traditional Chinese medicines such as Xiao-Er-Zhi-Bao-Wan (XEZBW), have been widely used for thousands of years. However, events associated with arsenic-induced ailments have increasingly become a public concern. To address the toxicity of XEZBW, we studied the histopathology and blood biochemistry of rats exposed to XEZBW using technology like high-performance liquid chromatography-inductively coupled mass spectrometry to determine arsenic speciation. Our results demonstrated that dimethylarsinic acid (DMA) increased from 18.57 ± 7.45 to 22.74 ± 7.45 ng/g in rat kidney after oral administration for 7 and 14 days, which was 10-fold higher than the levels observed in controls. Trivalent arsenite As(III) showed a large increase on day 7 (26.99 ± 1.98 ng/g), followed by a slight decrease on day 14 (13.67 ± 6.48 ng/g). Total arsenic levels on day 7 (185.52 ± 24.56 ng/g) and day 14 (198.57 ± 26.26 ng/g) were nearly twofold higher than that in the control group (92.77 ± 14.98 ng/g). Histopathological analysis showed mild injury in the liver and kidney of rats subjected to oral administration of realgar for 14 days. As in the XEZBW groups, a mild injury in these organs was observed after administration for 14 days. This study inferred that the toxicity of arsenic was concentration- and time-dependent. The accumulation of DMA, a byproduct of choline metabolism, was responsible for inducing higher toxicity. Therefore, we concluded that measuring the levels of DMA, instead of total arsenic, might be more suitable for evaluating the toxicity of realgar-containing traditional Chinese medicines.

Uncovering the antifungal components from turmeric (Curcuma longa L.) essential oil as Aspergillus flavus fumigants by partial least squares

Highly efficient and eco-friendly antifungal fumigants are desirable in food and crop production. Although turmeric (Curcuma longa L.) essential oil is known to have a potent antifungal effect, the quality of whole essential oil can be unstable, leading to unreliable antifungal activities. The aim of the present study is to uncover the active individual compounds in turmeric essential oil that provide the antifungal properties using a convenient chemometric model. The Aspergillus flavus inhibition activities of essential oils derived from 24 batches of Curcuma longa L. were evaluated, with various fumigation concentrations from 50 μL to 500 μL essential oils per plate. Meanwhile, eighteen volatile compounds were identified by static headspace gas chromatography-mass spectrometry. To combine the antifungal activities and chemical profiles with the spectrum-effect relationship based on the partial least squares model, three volatile compounds (i.e., eucalyptol, beta-pinene and camphor) were identified and verified as the most potent antifungal compounds by their higher contribution factor to antifungal indexes. Thus, this research will provide a useful approach to screen bioactive compounds, and these three compounds are promising antifungal alternatives to conventional treatments for the control of A. flavus contamination.

Occurrence of Pesticides in Pericarpium Citri Reticulatae and Related Products Using Syringe Filter-Based Cleanup

The study established a method of rapid cleanup using an easy to operate syringe filter and gas chromatography coupled to an electron capture detector (GC-ECD) to detect 37 pesticides in Pericarpium Citri Reticulatae and related products. The critical parameters related to clean-up efficiency were optimized. The adsorbents, which included PestiCarb (0.5 g), primary secondary amine (PSA, 0.25 g) and Florisil (1.0 g), were loaded in turn and push-pull was performed 4 times within a 1 min operating time. Under optimized conditions, the recovery of pesticides ranged from 61.6 to 128.6% at three spiked levels (25, 50, 500 μg kg). After analysis by GC-ECD and confirmation by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS), 8 out of 57 batches of peels were found to be contaminated with hexachlorobenzene, dicofol, procymidone and p,p’-DDE (dichlorodiphenyldichloroethylene). The most frequently (10.5%) occurring pollutants were hexachlorobenzene and dicofol. In addition, 5 batches contained prohibited or restricted persistent organochlorines at levels above regulations, and 5 of these peels contained more than two pesticides.

Occurrence of multi-class mycotoxins in Menthae haplocalycis analyzed by ultra-fast liquid chromatography coupled with tandem mass spectrometry

To determine the presence of multi-class mycotoxins in Menthae haplocalycis, a sample processing procedure based on a modified quick, easy, effective, rugged, and safe method, and a rapid and accurate testing method using ultra-fast performance liquid chromatography coupled with tandem mass spectrometry, was developed and validated. We systematically evaluated the methodology for multi-mycotoxin analysis in the Menthae haplocalycis samples, and chose matrix-matched calibration curves as a reference to calculate the recoveries. Overall, the average recoveries varied between 67.1 and 103%, with relative standard deviations ranging from 0.34 to 10.3%. The optimized and validated method was applied to detect the presence of the target mycotoxins in 40 batches of Menthae haplocalycis samples. Results showed that the levels of mycotoxins varied among the samples. The most prevalent mycotoxin was tentoxin, followed by alternariol, alternariol monomethyl ether, zearalenone, fumonisin B2 , fumonisin B1 , ochratoxin A, aflatoxin B1 , aflatoxin B2 , aflatoxin G1 , and T-2 toxin. The analytical method developed herein could be applied for the routine monitoring of multi-mycotoxins in Menthae haplocalycis.