Boyan Gao

Chemical profiling of triacylglycerols and diacylglycerols in cow milk fat by ultra-performance convergence chromatography combined with a quadrupole time-of-flight mass spectrometry.

An ultra-performance convergence chromatography (UPC(2)) system coupled with quadrupole time-of-flight mass spectrometry (Q-TOF-MS) was successfully utilised to analyse triacylglycerols and diacylglycerols in cow milk fat. This novel approach obtained an improved resolution of triacylglycerols in comparison to previously reported chromatographic methods combined with MS detector in a shorter analytical time. A total of 49 triacylglycerols and 7 diacylglycerols were identified according to their secondary MS profiles and elementary composition. Furthermore, UPC(2) is an environmental friendly analytical method with a drastic reduction of organic solvent usage. The established UPC(2)-MS approach has potential application in lipidomics as an alternative method besides LC-MS and GC-MS.

Antioxidant properties and phytochemical composition of China-grown pomegranate seeds

Four cultivars of Shanxi-grown pomegranate seeds were investigated for their phytochemical composition and antioxidant properties. Pomegranate seed oils were extracted and analysed for their fatty acid profiles, and tocopherol and carotenoid contents. The defatted flours were extracted with 50% acetone or 80% methanol, and evaluated for levels of phenolics, flavonoids and proanthocyanidins, and scavenging capacities against DPPH and ABTS+ and their ferric ion reducing abilities. Pomegranate seed oil was rich in punicic acid (73.5-78.8g/100g oil) and total tocopherols (5.3-12.0μmol/g). The 50% acetone and 80% methanol were appropriate solvents for extraction of total phenolic and total flavonoid, respectively. The four cultivars were significantly different in levels of phenolics, flavonoids, proanthocyanidins and their antioxidant properties (P<0.05), generally flowing an order: Suanshiliu>Tianhongdan>Sanbaitian≈Jingpitian. This study will assist in the cultivar selection of the above pomegranate seeds for commercial production to meet the market demand.

Acute oral toxicity of 3-MCPD mono- and di-palmitic esters in Swiss mice and their cytotoxicity in NRK-52E rat kidney cells.

The acute oral toxicity of 1-palmitoyl-3-chloropropanediol (3-MCPD 1-monopalmitate) and 1,2-bis-palmitoyl-3-chloropropanediol (3-MCPD dipalmitate) in Swiss mice were examined, along with their cytotoxicity in NRK-52E rat kidney cells. LD50 (median lethal dose) value of 3-MCPD 1-monopalmitate was determined 2676.81 mg/kg body weight (BW). The results showed that 3-MCPD 1-monopalmitate dose-dependently decreased the mean body weight, and caused significant increase of serum urea nitrogen and creatinine in dead mice compared to the control and survived mice. Major histopathological changes in mice fed 3-MCPD 1-monopalmitate were renal tubular necrosis, protein casts and spermatids decrease in the seminiferous tubules. According to the limit test for 3-MCPD dipalmitate, LD50 value of 3-MCPD dipalmitate was presumed to be greater than 5000 mg/kg BW. Obvious changes were not observed on mean body weight, absolute and relative organ weight or serum urea nitrogen and creatinine levels in mice fed 3-MCPD dipalmitate. However, renal tubular necrosis, protein casts and spermatids decrease were also observed in the dead mice. In addition, MTT and LDH assay results only showed the cytotoxicity of 3-MCPD 1-monopalmitate in NRK-52E rat kidney cells in a dose-dependent manner. Together, the results indicated a greater toxicity of 3-MCPD 1-monopalmitate compared to 3-MCPD dipalmitate.

Identification and Quantification of Phytochemical Composition and Anti-inflammatory, Cellular Antioxidant, and Radical Scavenging Activities of 12 Plantago Species

Twenty-eight seed samples of 12 Plantago species were investigated for their chemical compositions and anti-inflammatory, cellular antioxidant, and radical scavenging properties. A new UPLC-UV procedure was developed and applied to quantify acteoside and geniposidic acid, the characteristic constituents of the genus Plantago. The amounts of acteoside and geniposidic acid ranged from 0.07 to 15.96 mg/g and from 0.05 to 10.04 mg/g in the tested samples, respectively. Furthermore, 26 compounds were tentatively identified by UPLC/Q-TOF-MS analysis. The Plantago samples significantly differed in their phytochemical compositions. The extracts of Plantago seeds also showed inhibitory effects on LPS-induced IL-1β, IL-6, and COX-2 mRNA expression in RAW 264.7 mouse macrophage cells. Additionally, significant variations were observed among different samples on cellular antioxidant activities in HepG2 cells, as well as DPPH and hydroxyl radical scavenging capacities. The results from this study may be used to promote the use of the genus Plantago in improving human health.

Partial Least-Squares-Discriminant Analysis Differentiating Chinese Wolfberries by UPLC–MS and Flow Injection Mass Spectrometric (FIMS) Fingerprints

Lycium barbarum L. fruits (Chinese wolfberries) were differentiated for their cultivation locations and the cultivars by ultraperformance liquid chromatography coupled with mass spectrometry (UPLC-MS) and flow injection mass spectrometric (FIMS) fingerprinting techniques combined with chemometrics analyses. The partial least-squares-discriminant analysis (PLS-DA) was applied to the data projection and supervised learning with validation. The samples formed clusters in the projected data. The prediction accuracies by PLS-DA with bootstrapped Latin partition validation were greater than 90% for all models. The chemical profiles of Chinese wolfberries were also obtained. The differentiation techniques might be utilized for Chinese wolfberry authentication.

Characterisation of organic and conventional sweet basil leaves using chromatographic and flow-injection mass spectrometric (FIMS) fingerprints combined with principal component analysis

Sweet basil, Ocimum basilicum, is one of the most important and wildly used spices and has been shown to have antioxidant, antibacterial, and anti-diarrheal activities. In this study, high performance liquid chromatographic (HPLC) and flow-injection mass spectrometric (FIMS) fingerprinting techniques were used to differentiate organic and conventional sweet basil leaf samples. Principal component analysis (PCA) of the fingerprints indicated that both HPLC and FIMS fingerprints could effectively detect the chemical differences in the organic and conventional sweet basil leaf samples. This study suggested that the organic basil sample contained greater concentrations of almost all the major compounds than its conventional counterpart on a per same botanical weight basis. The FIMS method was able to rapidly differentiate the organic and conventional sweet basil leaf samples (1min analysis time), whereas the HPLC fingerprints provided more information about the chemical composition of the basil samples with a longer analytical time.

Free Radical Mediated Formation of 3-Monochloropropanediol (3-MCPD) Fatty Acid Diesters

The present study was conducted to test the hypothesis that a free radical was formed and mediated the formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters, a group of food contaminants, from diacylglycerols at high temperature under a low-moisture condition for the first time. The presence of free radicals in a vegetable oil kept at 120 °C for 20 min was demonstrated using an electron spin resonance (ESR) spectroscopy examination with 5,5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. ESR investigation also showed an association between thermal treatment degree and the concentration of free radicals. A Fourier transform infrared spectroscopy (FT-IR) analysis of sn-1,2-stearoylglycerol (DSG) at 25 and 120 °C suggested the possible involvement of an ester carbonyl group in forming 3-MCPD diesters. On the basis of these results, a novel free radical mediated chemical mechanism was proposed for 3-MCPD diester formation. Furthermore, a quadrupole-time of flight (Q-TOF) MS/MS investigation was performed and detected the DMPO adducts with the cyclic acyloxonium free radical (CAFR) and its product MS ions, proving the presence of CAFR. Furthermore, the free radical mechanism was validated by the formation of 3-MCPD diesters through reacting DSG with a number of organic and inorganic chlorine sources including chlorine gas at 120 and 240 °C. The findings of this study might lead to the improvement of oil and food processing conditions to reduce the level of 3-MCPD diesters in foods and enhance food safety.

Differentiating Organic from Conventional Peppermints Using Chromatographic and Flow Injection Mass Spectrometric (FIMS) Fingerprints

High-performance liquid chromatography (HPLC) and flow injection mass spectrometric (FIMS) fingerprinting techniques were tested for their potential in differentiating organic and conventional peppermint samples. Ten organic and ten conventional peppermint samples were examined using HPLC-UV and FIMS methods. Principal component analysis (PCA) showed that both HPLC and FIMS fingerprints could determine the difference in the commercial organic and conventional peppermints. FIMS fingerprinting provided a rapid test to differentiate organic and conventional peppermints in 1 min of analysis and has potential for high-throughput applications. On the other hand, HPLC fingerprints provide more information about the chemical composition of the samples, but take a longer time to differentiate organic and conventional peppermint samples.

Formation of 3-Monochloro-1,2-propanediol (3-MCPD) Di- and Monoesters from Tristearoylglycerol (TSG) and the Potential Catalytic Effect of Fe2+ and Fe3+

This study investigated whether and how triacylglycerol (TAG) may serve as a precursor for 3-monochloro-1,2-propanediol (3-MCPD) fatty acid ester formation using tristearoylglycerol (TSG). TSG was reacted with inorganic chloride compounds including NaCl, KCl, FeCl2, CuCl2, ZnCl2, FeCl3 and dry HCl, or organic chlorine compound lindane at different temperatures. Only FeCl2 and FeCl3 were able to form 3-MCPD esters from TSG. Further electron spin resonance (ESR) determination of TSG, Fe2(SO4)3 and 5,5-dimethylpyrroline-N-oxide (DMPO) reactions revealed potential of Fe ion in promoting free radical generations under the experimental conditions. To further confirm the effect of Fe ion, chelating agent (EDTA-2Na) was added to the model reactions. The results showed for the first time that EDTA-2Na was able to reduce the generation of 3-MCPD esters. In addition, FT-IR examination indicated a possible involvement of a carbonyl group during the reaction. Taking all the observations together, the possible mechanisms, involving the formation of either a cyclic acyloxonium or a glycidol ester radical intermediate, were proposed for generating 3-MCPD fatty acid di- and mono- esters from TAG under a high temperature and low moisture condition, as well as the coformation of glycidol esters. The results from this study may be useful for reducing the level of 3-MCPD esters and related toxicants in the refined edible oils and food products.

Differentiating Organic and Conventional Sage by Chromatographic and Mass Spectrometry Flow Injection Fingerprints Combined with Principal Component Analysis

High-performance liquid chromatography (HPLC) and flow injection electrospray ionization with ion trap mass spectrometry (FIMS) fingerprints combined with principal component analysis (PCA) were examined for their potential in differentiating commercial organic and conventional sage samples. The individual components in the sage samples were also characterized with an ultraperformance liquid chromatograph with a quadrupole-time-of-flight mass spectrometer (UPLC Q-TOF MS). The results suggested that both HPLC and FIMS fingerprints combined with PCA could differentiate organic and conventional sage samples effectively. FIMS may serve as a quick test capable of distinguishing organic and conventional sages in 1 min and could potentially be developed for high-throughput applications, whereas HPLC fingerprints could provide more chemical composition information with a longer analytical time.