Liya Ge

The Chemical Composition and Biological Properties of Coconut (Cocos nucifera L.) Water

Coconut water (coconut liquid endosperm), with its many applications, is one of the world’s most versatile natural product. This refreshing beverage is consumed worldwide as it is nutritious and beneficial for health. There is increasing scientific evidence that supports the role of coconut water in health and medicinal applications. Coconut water is traditionally used as a growth supplement in plant tissue culture/micropropagation. The wide applications of coconut water can be justified by its unique chemical composition of sugars, vitamins, minerals, amino acids and phytohormones. This review attempts to summarise and evaluate the chemical composition and biological properties of coconut water.

Simultaneous analysis of different classes of phytohormones in coconut (Cocos nucifera L.) water using high-performance liquid chromatography and liquid chromatography–tandem mass spectrometry after solid-phase extraction

Coconut (Cocos nucifera L.) water, which contains many uncharacterized phytohormones is extensively used as a growth promoting supplement in plant tissue culture. In this paper, a high-performance liquid chromatography (HPLC) method was developed for the simultaneous determination of various classes phytohormones, including indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), abscisic acid (ABA), gibberellic acid (GA), zeatin (Z), N(6)-benzyladenine (BA), alpha-naphthaleneacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in young coconut water (CW). The analysis was carried out using a reverse-phase HPLC gradient elution, with an aqueous mobile phase (containing 0.1% formic acid, pH adjusted to 3.2 with triethylamine (TEA)) modified by methanol, and solute detection made at 265 nm wavelength. The method was validated for specificity, quantification, accuracy and precision. After preconcentration of putative endogenous phytohormones in CW using C(18) solid-phase extraction (SPE) cartridges, the HPLC method was able to screen for putative endogenous phytohormones present in CW. Finally, the identities of the putative phytohormones present in CW were further confirmed using independent liquid chromatography-tandem mass spectrometry (LC-MS/MS) equipped with an electrospray ionization (ESI) interface.

Determination of bisphenol A and naphthols in river water samples by capillary zone electrophoresis after cloud point extraction.

As a first attempt, cloud point extraction (CPE) was developed to preconcentrate bisphenol A (BPA), α-naphthol and β-naphthol prior to performing capillary zone electrophoresis (CZE) analysis. The parameters influencing the CPE efficiency, such as Triton X-114 concentrations, pH value, extraction time and temperature were systematically evaluated. After diluting with acetonitrile, the surfactant-rich phase of CPE can be injected directly into the CE instrument. The CZE baseline separation was achieved with running buffer (pH 9.5) composed of 50mM sodium tetraborate in 30% (v/v) methanol, and an applied voltage of 25 kV. Under the optimized CPE and CZE conditions, an preconcentration factor of 50 times could be obtained and the limit of quantification for the three analytes were found to be 1.67 μg L(-1), 0.80 μg L(-1) and 0.67 μg L(-1) for BPA, α-naphthol and β-naphthol, respectively. The proposed methods have shown to be a green, rapid and effective approach for determination of three analytes present in river water samples.

Paper Disk on Screen Printed Electrode for One-Step Sensing with an Internal Standard

A point-of-care device, an ideal application is to provide a direct answer for an analysis with only a simple sample introduction. In order to meet the requirements, reagents storage, and self-calibration must be integrated on the portable device. This study describes a device with a paper disk impregnated with reagents including an internal standard and buffer on a screen printed electrode leading to accurate result in a single-step assay. We demonstrated on the applicability of this device by detection of trace lead (ppb level) in 10 μL solution based on the simultaneous (in situ) plating of bismuth and heavy metals onto electrode, which formed alloys followed by anodic stripping, Zn(II) was employed as an internal standard. We believe this approach is attractive for use in field based portable devices.

Determination of metabolites in Uncaria sinensis by HPLC and GC-MS after green solvent microwave-assisted extraction.

Uncaria sinensis (Oliv.) Havil (Rubiaceae) has been used as an important Traditional Chinese Medicine (TCM) herb for the treatment of fevers and various nervous disorders. The major bioactive secondary metabolites from different classes of chemical compounds, i.e. organic acid, flavonoid and alkaloid, present in this TCM herb, namely catechin, caffeic acid, epicatechin and rhynchophylline, were extracted by microwave-assisted extraction (MAE) method with ultra-pure water as the extraction solvent. The optimal extraction conditions for this green solvent MAE method were found to be 100°C for 20 min. The recoveries of the compounds were found to be comparable to that of heating under reflux using ultra-pure water for 60 min. The method precision (RSD, n=6) was found to vary from 0.19% to 5.60% for the proposed method on different days for the secondary metabolites. Simultaneously, the key primary metabolites such as sucrose and phenylalanine for the biosynthesis of bioactive secondary metabolites were successfully characterized by GC-MS. Furthermore, an approach using the combination of primary and secondary metabolite profiling based on their chemical fingerprints with Principal Component Analysis (PCA) was successfully developed to evaluate the quality of U. sinensis obtained from different sources. This approach was shown to be feasible in discriminating U. sinensis from different origins and thus a potential application for the quality control of other medicinal herbs.

Paper-based enzyme immobilization for flow injection electrochemical biosensor integrated with reagent-loaded cartridge toward portable modular device.

Paper-based enzyme immobilization for a flow injection electrochemical biosensor integrated with a reagent-loaded cartridge toward a portable device was developed. A paper disk was immobilized with enzyme, then it was integrated in a flow cell as an electrochemical biosensor. A silicon tube reagent-loaded cartridge was integrated into the system, a complicated procedure was simplified as a one-click operation toward development for point-of-care applications. In this research, glucose oxidase (GOx) was employed as a model enzyme, silver ion as an inhibition reagent for GOx, and EDTA as a regeneration reagent. When GOx was inhibited by silver ions, glucose was introduced for electrochemical measurements before and after inhibited enzyme regeneration and the difference was caused by silver inhibition. The modular device has great potential for other applications, e.g., detection of enzyme activity and substrate. The platform based on double-test mode provided accurate results due to elimination of an average or control value in comparison with classical routine approaches.

A novel method of protein extraction from yeast using ionic liquid solution.

As the first attempt, ionic liquid solutions have been employed for direct extraction of proteins from yeast cells. Compared with effects of 21 different ionic liquid solutions on the extraction efficiency, 3-(dimethylamino)-1-propylaminium formate ([DMAPA]FA) was selected as the suitable ionic liquid solution. As this ionic liquid can be easily removed under vacuum, contamination by the chemical noise can be effectively reduced. Both sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and 2-dimensional gel electrophoresis (2-DE) were employed to separate numerous proteins, and the results indicated that the chemical properties of target proteins remained unchanged during the extraction process. Furthermore, extracted proteins were applicable to the standard method for Western blotting which showed proteins maintain immunoreactivity and biological functions. These investigations indicated that the ionic liquid [DMAPA]FA is a promising reagent for protein extraction in yeast cells.

Chiral capillary electrophoresis with cationic pyrrolidinium‐β‐cyclodextrin derivatives as chiral selectors

New single-isomer, cationic beta-cyclodextrins, including mono-6-deoxy-6-pyrrolidine-beta-cyclodextrin chloride (pyCDCl), mono-6-deoxy-6-(N-methyl-pyrrolidine)-beta-cyclodextrin chloride (N-CH(3)-pyCDCl), mono-6-deoxy-6-(N-(2-hydroxyethyl)-pyrrolidine)-beta-cyclodextrin chloride (N-EtOH-pyCDCl), mono-6-deoxy-6-(2-hydroxymethyl-pyrrolidine)-beta-cyclodextrin chloride (2-MeOH-pyCDCl) were synthesized and used as chiral selectors in capillary electrophoresis for the enantioseparation of carboxylic and hydroxycarboxylic acids and dansyl amino acids. The unsubstituted pyCDCl exhibited the greatest resolving ability. Most analytes were resolved over a wide range of pH from 6.0 to 9.0 with this chiral selector. In general, increasing pH led to a decrease in resolution. The effective mobilities of all the analytes were found to decrease with increasing CD concentration. The optimal concentration for most carboxylic acids and dansyl amino acid was in the range 5-7.5 mM and >15 mM for hydroxycarboxylic acids. (1)H NMR experiments provided direct evidence of inclusion in the CD cavity.

Enhanced gas chromatography-mass spectrometry method for bacterial polyhydroxyalkanoates analysis.

A gas chromatography-mass spectrometry method for quantification of polyhydroxyalkanoates (PHAs), containing 4-carbon to 16-carbon monomers, even in the absence of standards, was developed. Strong linear correlations existed between PHA carbon number and retention time/response factor (R(2) ≥ 0.987). Based on the correlations, high recovery values, between 100.5% and 114.3%, were obtained for PHA polymers.

Mass spectrometric evidence for the occurrence of plant growth promoting cytokinins in vermicompost tea

Through their decomposing activities, earthworms produce rich organic fertilizers called vermicomposts containing mineral nutrients and anecdotal evidence of biologically active phytohormones. Aqueous extracts of vermicomposts, namely vermicompost tea (VT), have positive effects on plant growth. It has been postulated that trace amounts of phytohormones in vermicomposts or its VT are beneficial for plant growth and development. We therefore screened for the different classes of phytohormones (auxins, cytokinins, abscisic acid, and gibberellin) in VT using liquid chromatography–tandem mass spectrometry (LC–MS/MS) after solid-phase extraction. VT was produced by earthworms being fed with a mixture of water hyacinth (Eichhornia crassipes) and chicken manure at a ratio of 4:1 (w/w). This investigation is the first mass spectrometric evidence for the presence of cytokinins in VT: namely trans-Zeatin (tZ), N6-Isopentenyladenine (iP) and N6-Isopentenyladenosine (iPR), which were present at 0.06, 3.33, and 0.02 nmol L–1, respectively. The successful detection and quantitation of cytokinins in VT provided direct evidence to explain the growth efficacy of applying VT in order to enhance plant growth and development. We postulated that they were microbially synthesized due to the abundance of microbial communities in the vermicompost.