Haitian Zhao

Multi-residue method for determination of seven neonicotinoid insecticides in grains using dispersive solid-phase extraction and dispersive liquid–liquid micro-extraction by high performance liquid chromatography

A method using dispersive solid-phase extraction and dispersive liquid-liquid micro-extraction cleanup followed by high performance liquid chromatography (HPLC) has been established for determination of seven neonicotinoid insecticides residues in grains including brown rice, maize, millet and oat. Based on an appraisal of the characteristics of HPLC, validation experiments were conducted for seven neonicotinoid insecticides. In the method, dispersive solid-phase extraction was carried out using PSA and bonded C18 coupled with graphitised carbon black with acetonitrile as the eluted solvent. In the linear range of each pesticide, the correlation coefficient was R(2) ≥ 0.99. At the low, medium and high three fortification levels of 0.05-0.8 mg kg(-1), recoveries fell within 76-123%. The relative standard deviation was between 0.9% and 12.6% for seven neonicotinoid pesticides. Low limits of detection (0.002-0.005 mg kg(-1)) and quantification (0.007-0.018 mg kg(-1)) were readily achieved with this method for all tested pesticides.

Multiresidue method for determination of 88 pesticides in berry fruits using solid-phase extraction and gas chromatography–mass spectrometry: Determination of 88 pesticides in berries using SPE and GC–MS

A method using solid phase extraction (SPE) cleanup followed by gas chromatography-mass spectrometry (GC-MS) has been established for quantitative determination of 88 pesticide residues in berry fruits including raspberry, strawberry, blueberry and grape. Based on an appraisal of the characteristics of GC-MS, validation experiments were conducted for 88 pesticides. In the method, solid-phase extraction was carried out using Envi-Carb cartridge coupled with NH(2)-LC cartridge with acetonitrile-toluene (3:1, v/v) as the eluted solvent. In the linear range of each pesticide, the correlation coefficient was R(2)⩾0.99. At the low, medium and high three fortification levels of 0.05-0.5mgkg(-1), recoveries fell within 63-137%. The relative standard deviation was between 1% and 19% for all 88 pesticides. Low limits of detection (0.006-0.05mgkg(-1)) and quantification (0.02-0.15mgkg(-1)) were readily achieved with this method for all tested pesticides.

Determination of free amino acids and 18 elements in freeze-dried strawberry and blueberry fruit using an Amino Acid Analyzer and ICP-MS with micro-wave digestion

The objective of this study was to investigate the level of 18 trace elements of two freeze-dried samples from the Blueberry (Vaccinium corymbosum) and the Strawberry (Fragaria × Ananassa). The total free amino acid composition in the blueberry and strawberry was determined by an Amino Acid Analyzer. Eleven free amino acids were found in both berries. The trace elements in each dried fruit sample were determined by ICP-MS with microwave digestion. The linearity range of the standard curves was 0-1250.0 μg L(-1) (Mg, P, K, Ca),while in all cases, except for B, Na, Al, Cr, Mn, Fe, Ni, Cu, Zn, Se, Cd, Pb, Ge and As, which was 125.0 μg mL(-1), all related coefficients were above 0.9999; recovery was in the range of 79.0-106.8%. Minor concentrations of nutritional elements were found in each freeze-dried berry. In sum, the toxic trace element analysis found the content of toxic trace elements in each freeze-dried berry sample was safe for human consumption and that the overall quality of the blueberry surpassed that of the strawberry. The results certify that the two freeze-dried berries have potential for human consumption in value-added products and have a certain theoretical and practical significance.

Chemical Composition and Antioxidant Activities of Three Polysaccharide Fractions from Pine Cones

The traditional method of gas chromatography-mass spectrometry for monosaccharide component analysis with pretreatment of acetylation is described with slight modifications and verified in detail in this paper. It was then successfully applied to the quantitative analysis of component monosaccharides in polysaccharides extracted from the pine cones. The results demonstrated that the three pine cone polysaccharides all consisted of ribose, rhamnose, arabinose, xylose, mannose, glucose and galactose in different molar ratios. According to the recovery experiment, the described method was proved accurate and practical for the analysis of pine cone polysaccharides, meeting the need in the field of chemical analysis of Pinus plants. Furthermore; the chemical characteristics, such as neutral sugar, uronic acids, amino acids, molecular weights, and antioxidant activities of the polysaccharides were investigated by chemical and instrumental methods. The results showed that the chemical compositions of the polysaccharides differed from each other, especially in the content of neutral sugar and uronic acid. In the antioxidant assays, the polysaccharide fractions exhibited effective scavenging activities on ABTS radical and hydroxyl radical, with their antioxidant capabilities decreasing in the order of PKP > PAP > PSP. Therefore, although the polysaccharide fractions had little effect on superoxide radical scavenging, they still have potential to be developed as natural antioxidant agents in functional foods or medicine.

Characterization and bioactivity of polysaccharides obtained from pine cones of Pinus koraiensis by graded ethanol precipitation.

Pinus koraiensis polysaccharides (PKP) were extracted by hot water from P. koraiensis pine cones. Five polysaccharide fractions named PKP-A, PKP-B, PKP-C, PKP-D and PKP-E were successfully separated at final ethanol concentrations of 30%, 50%, 60%, 70% and 80%, respectively. HPLC, FT-IR, GC-MS and automatic amino-acid analysis were applied to investigate their chemical characteristics. Monosaccharide component analysis indicated that the five fractions were all composed of d-ribose, l-rhamnose, l-arabinose, d-xylose, d-mannose, d-glucose and d-galactose, but their molar ratios were quite different. HPLC results revealed that the polysaccharides precipitated by higher concentrations of ethanol solution had lower molecular masses. Moreover, the antioxidant activities of the five fractions were studied on the basis of hydroxyl radical and ABTS radical scavenging tests. The five graded polysaccharide fractions exhibited good inhibitory power, and MTT tests in vitro showed the IC50 of PKP-A and PKP-E were 1,072.5 and 2,070.0 μg·mL−1, respectively. These results demonstrated that the PKP could be a potential source of natural antioxidants or dietary supplements.

Protective effect of anthocyanin from Lonicera Caerulea var. Edulis on radiation-induced damage in mice.

The radioprotective effect of anthocyanin extracted from Lonicera caerulea var. edulis (ALC), was studied in ICR mice. Different doses of ALC were intragastrically administered to mice once a day, prior to radiation. After two weeks, the mice received a one-time 5 Gy whole body 60Coγ radiation. The spleen index, thymus index, activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), malondialdehyde (MDA) content, and glutathione (GSH) content in liver tissue were measured. Compared with the radiation control group, the levels of MDA in all ALC treated groups decreased significantly (p < 0.05). Moreover, the GSH content, activities of SOD and GSH-Px in liver tissue were enhanced significantly (p < 0.05) in all ALC groups. These results demonstrate that ALC may be a potential radioprotector, and a further study of the molecular mechanism is needed for further application.

Plasma depolymerization of chitosan in the presence of hydrogen peroxide.

The depolymerization of chitosan by plasma in the presence of hydrogen peroxide (H2O2) was investigated. The efficiency of the depolymerization was demonstrated by means of determination of viscosity-average molecular weight and gel permeation chromatography (GPC). The structure of the depolymerized chitosan was characterized by Fourier-transform infrared spectra (FT-IR), ultraviolet spectra (UV) and X-ray diffraction (XRD). The results showed that chitosan can be effectively degradated by plasma in the presence of H2O2. The chemical structure of the depolymerized chitosan was not obviously modified. The combined plasma/H2O2 method is significantly efficient for scale-up manufacturing of low molecular weight chitosan.

Protective effects of polysaccharides from soybean meal against X-ray radiation induced damage in mouse spleen lymphocytes.

The aim of this study was to investigate radioprotective effect of the polysaccharides from soybean meal (SMP) against X-ray radiation-induced damage in mouse spleen lymphocytes. MTT and comet assay were performed to evaluate SMP’s ability to prevent cell death and DNA damage induced by radiation. The results show that, X-ray radiation (30 KV, 10 mA, 8 min (4 Gy)) can significantly increase cell death and DNA fragmentation of mouse spleen lymphocytes. Pretreatment with SMP for 2 h before radiation could increase cell viability, moreover, the SMP can reduce X-ray radiation-induced DNA damage. The percentage of tail DNA and the tail moment of the SMP groups were significantly lower than those of the radiation alone group (p < 0.05). These results suggest SMP may be a good candidate as a radioprotective agent.

Effect of pesticide 1-[6-chloro-3-methyl-pyridyl-8-nitro-7-methyl-1 2 3 5 6 7-hexahydro imidazo (1,2a)]-pyridine when responding to a wheat plant's antioxidant defense system.

The purpose of this research was to establish an analytical method for analysing the 1-[6-chloro-3-methyl-pyridyl-8-nitro-7-methyl-1 2 3 5 6 7-hexahydro imidazo-(1,2a)]-pyridine (IPP) residue levels and to evaluate the difference in plant growth and its physical condition. A high performance liquid chromatography connected to a diode array detector (HPLC-DAD) was also employed. The results showed that the content of protein and water soluble carbohydrate (WSC) treated by IPP were initially higher with a significant delayed decrease. The biomarker response showed, even at a lower dose rate, exposure to the IPP caused stress effects and modified the activity of superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT) and polyphenol oxidase (PPO). Different patterns of biomarker responses were observed by an increase in SOD and malondialdehyde (MDA), and differential effects for antioxidant enzymes with a decrease in CAT, POD and PPO. The conclusions show that this profile of biomarker variation could represent a useful method to characterise exposure to IPP in a wheat plant.

Polyphenols from pinecones of Pinus koraiensis induce apoptosis in colon cancer cells through the activation of caspase in vitro

We had previously extracted and purified a polyphenol from P. koraiensis pinecone (PPP), and evaluated its antiproliferative activities against different cancer cells lines. In the present study, we further improved the purity of PPP through the gradient elution method by different concentrations of ethanol (20%, 40% and 60%), so as to study their antitumor effects. Then, the purity and the influence upon cell viability of the purified components from PPP (PPP-20, PPP-40 and PPP-60) were evaluated. The results showed that PPP-40 had the highest phenolic purity (57.25 ± 1.83%) and exhibited the strongest inhibition (EC50 0.21 ± 0.03 mg mL−1) against LOVO cells in a dose-dependent manner. Catechin and taxifolin, the main components of PPP-40, may contribute to its antitumor activity. Moreover, we further investigated the molecular mechanisms of the PPP-40-induced apoptosis. The DNA damage in LOVO cells was observed by PI staining and comet assay. Besides, the apoptosis rates were further detected by flow cytometry. Consequently, the data showed that PPP-40 could significantly disrupt the mitochondrial membrane potential (MMP), reduce the content of adenosine 5′-triphosphate (ATP) and increase the production of reactive oxygen species (ROS). All the results indicated the mitochondrial dysfunction was involved in the PPP-40-induced apoptosis. Meanwhile, the typical markers of apoptosis involving the intrinsic and extrinsic pathways were analyzed as well. This showed that PPP-40 could not only promote the intrinsic apoptosis by increasing the release of cytochrome c (cyt c) and activating caspase-9 and -3, but also induce extrinsic apoptosis by activating caspase-8.