Biomedical subjects

Hua-Bin Li

Publications and source records attributed to Hua-Bin Li.

At least 19 recordsLinked to original sources

PubMed2006

Elucidation of n-butyl benzyl phthalate biodegradation using high-performance liquid chromatography and gas chromatography-mass spectrometry.

n-Butyl benzyl phthalate (BBP) is an endocrine-disrupting chemical. A bacterium species capable of using BBP as the sole source of carbon and energy was isolated from mangrove sediment. Effects of BBP concentration, pH, temperature, and salinity on BBP biodegradation were studied. The optimum pH, temperature, and salinity for the BBP biodegradation were 7.0, 37 degrees C, and 15 g L(-1), respectively. BBP was completely degraded within 6 days under optimum conditions, and the biodegradation of BBP could be fitted to a first-order kinetic model. The major metabolites of BBP biodegradation were identified as mono-butyl phthalate, mono-benzyl phthalate, phthalic acid, and benzoic acid by using high-performance liquid chromatography and gas chromatography-mass spectrometry. A preliminary metabolic pathway was proposed for the biodegradation of BBP.

Benzoic Acid↗

PubMed2006

Kinetics of n-butyl benzyl phthalate degradation by a pure bacterial culture from the mangrove sediment.

n-Butyl benzyl phthalate (BBP) is an endocrine-disrupting chemical. Biodegradation of BBP by a bacterium, Pseudomonas fluorescens B-1, isolated from the mangrove sediment, was investigated. The microorganism can utilize BBP as the sole carbon and energy source, where concentrations of BBP disappeared within 6 days under shake culture conditions. Effects of BBP concentration, pH, temperature, and salinity on BBP biodegradation were studied, respectively. The process of BBP biodegradation was monitored by reversed-phase high-performance liquid chromatography with ultra-violet detection after solid-phase extraction. The biodegradation of BBP could be fitted to a first-order kinetic model. The major metabolites of BBP degradation were identified as mono-butyl phthalate, mono-benzyl phthalate, phthalic acid and benzoic acid by gas chromatography-mass spectrometry, and a preliminary metabolic pathway of BBP was proposed.

Biodegradation, Environmental↗

PubMed2005

Determination of paralytic shellfish poisoning toxins in cultured microalgae by high-performance liquid chromatography with fluorescence detection.

A novel method for the determination of paralytic shellfish poisoning (PSP) toxins using high-performance liquid chromatography with fluorescence detection was developed. The fluorescent derivates of neosaxitoxin (neoSTX), saxitoxin (STX), gonyautoxins 1 and 4 (GTX1+4), and gonyautoxins 2 and 3 (GTX2+3) were separated on a muBondapak NH2 column (300 mm x 3.9 mm, 10 microm) using water and acetate buffer (pH 6.5) as the mobile phase (1.00 mL min(-1)) in gradient mode with fluorescence detection at 390 nm (excitation at 330 nm). The linear ranges of neoSTX, STX, GTX1+4 and GTX2+3 were 3.31-331, 0.952-95.2, 3.78-378 and 0.124-12.4 ng mL(-1), respectively. The detection limits of neoSTX, STX, GTX1+4 and GTX2+3 were 1.10, 0.32, 1.26 and 0.041 ng mL(-1), respectively. The method was successfully applied to the determination of PSP toxins in microalgae. The recoveries ranged from 88+/-2% to 107+/-4% and the relative standard deviations were 0.16% to 4.4%. The procedure is also environmentally friendly because no organic solvent is used in the mobile phase.

Amides↗

PubMed2005

Determination of vitamin B1 in seawater and microalgal fermentation media by high-performance liquid chromatography with fluorescence detection.

A highly sensitive high-performance liquid chromatographic method with fluorescence detection has been developed for determination of vitamin B(1). Vitamin B(1) was converted into a fluorescent compound by treatment with hydrogen peroxide-horseradish peroxidase and the derivative was subsequently analyzed by HPLC on a Waters Spherisorb ODS2 column (250 mm x 4.6 mm ID, 5 microm) with 40:60 methanol-pH 8.5 acetate buffer solution as mobile phase and fluorescence detection at 440 nm (with excitation at 375 nm). The calibration graph was linear from 5.00 x 10(-10) mol L(-1) to 5.00 x 10(-7) mol L(-1) for vitamin B1 with a correlation coefficient of 0.9991 (n = 9). The detection limit was 1.0 x 10(-10) mol L(-1). The method was successfully used for determination of vitamin B1 at pg mL(-1) levels in microalgal fermentation media and seawater after solid-phase extraction. Recovery was from 89 to 110% and the relative standard deviation was in the range 1.1 to 4.3%.

Chromatography, High Pressure Liquid↗

PubMed2005

Simultaneous decontamination of hexavalent chromium and methyl tert-butyl ether by UV/TiO2 process.

Hexavalent chromium and methyl tert-butyl ether (MTBE) are two important environmental pollutants. Simultaneous decontamination of Cr(VI) and MTBE was studied by UV/TiO2 process. The influences of pH and the concentrations of pollutants on the kinetics of the photocatalytic reactions were evaluated. Dark adsorption tests showed that the acidic pH favored the adsorption of Cr(VI) while neutral pH favored the adsorption of MTBE. Under UV irradiation, Cr(VI) reduction was observed in Cr(VI)/TiO2 system, and MTBE oxidation was observed in MTBE/TiO2 system. The system containing Cr(VI) and MTBE by UV/TiO2 process demonstrated the synergistic effect between oxidation of MTBE and reduction of Cr(VI). The results demonstrated that two pollutants Cr(VI) and MTBE could be eliminated simultaneously by UV/TiO2 process. tert-Butyl formate, tert-butyl alcohol and acetone were identified as primary degradation products of MTBE by gas chromatography-mass spectrometry in the degradation of MTBE by UV/TiO2 process.

Adsorption↗

PubMed2005

Preparative isolation and purification of phillyrin from the medicinal plant Forsythia suspensa by high-speed counter-current chromatography.

Forsythia suspensa (Thunb.) Vahl. has been used widely in traditional medicines to treat gonorrhea, erysipelas, inflammation, pyrexia and ulcer. It has also shown antioxidant activity, as well as antibacterial, antiviral, choleretic and antiemetic effects. A high-speed counter-current chromatography (HSCCC) method was developed for the preparative separation and purification of the bioactive molecule phillyrin from F. suspensa (Thunb.) Vahl. The crude phillyrin was obtained by extraction with 50% ethanol from the dried fruits of F. suspensa (Thunb.) Vahl. under sonication. Preparative HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (1:9:1:9, v/v/v/v) was successfully performed, and the components purified and collected were analyzed by high-performance liquid chromatography. The method yielded 5.6 mg phillyrin at 98.6% purity from 500 mg of the crude extract (1.2% phillyrin) with the recovery of 92% in a one-step separation.

Chromatography, High Pressure Liquid↗

PubMed2005

Isolation and purification of baicalein, wogonin and oroxylin A from the medicinal plant Scutellaria baicalensis by high-speed counter-current chromatography.

The medicinal plant Scutellaria baicalensis Georgi has been used widely in traditional Chinese medicine for anti-inflammation, anticancer, antiviral and antibacterial infections, reducing the total cholesterol level and decreasing blood pressures. A high-speed counter-current chromatography (HSCCC) method was developed for the preparative separation and purification of three bioactive flavonoids, namely, baicalein, wogonin and oroxylin A, from S. baicalensis Georgi. Preparative HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-n-butanol-water (1:1:8:10, v/v/v/v) was successfully performed by increasing the flow-rate of the mobile phase stepwise from 1.0 to 2.0 ml min(-1) after 4 h. The components purified and collected were analyzed by high-performance liquid chromatography. The method yielded 144.8 mg of baicalein at 95.7% purity, 50.2 mg of wogonin at 98.5% purity, and 12.4 mg of oroxylin A at 93.2% purity from 500 mg of the crude extract in a one-step separation. The recoveries of baicalein, wogonin and oroxylin A were 92.7%, 91.6% and 92.5%, respectively.

Chromatography, High Pressure Liquid↗

PubMed2005

Determination of methylmercury fluxes across the air-water and air-soil interfaces by gas chromatography with electron capture detection.

A method for the determination of methylmercury (MeHg) fluxes across the air-water and air-soil interfaces was developed using an in situ chamber. The MeHg in the air coming out of the chamber was captured by a column containing sulfhydryl cotton fiber adsorbent. MeHg was then desorbed from the column by using 2 mol L(-1) HCl. The MeHg in the effluent was extracted with benzene, and determined by gas chromatography with electron capture detection. Finally, the MeHg flux was calculated using the chamber. The method was applied to simulated experiments, and the results showed that the MeHg fluxes in the air-water system were higher than those in the air-soil-water system. The method was also successfully applied to the field measurements of an environment polluted by a chemical factory, and the results showed that the MeHg fluxes across the air-soil and air-water interfaces were 0.21-3.09 and 0.14-0.79 ng m(-2) h(-1), respectively. The method will be a useful tool in the environmental study of MeHg.

Journal Article↗

PubMed2005

Isolation and purification of the bioactive carotenoid zeaxanthin from the microalga Microcystis aeruginosa by high-speed counter-current chromatography.

High-speed counter-current chromatography was successfully applied for the first time to the isolation and purification of the bioactive carotenoid zeaxanthin from the cyanobacterium Microcystis aeruginosa. The crude zeaxanthin was obtained by extraction with organic solvents after the microalgal sample had been saponified. Preparative high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (8:2:7:3, v/v/v/v) was successfully performed yielding zeaxanthin at 96.2% purity from 150 mg of the crude extract in a one-step separation. The recovery of zeaxanthin was 91.4%. This was also the first report that zeaxanthin was successfully separated and purified from microalgae.

Chromatography, High Pressure Liquid↗

PubMed2005

Simultaneous separation and purification of five bioactive coumarins from the Chinese medicinal plant Cnidium monnieri by high-speed counter-current chromatography.

Cnidium monnieri (L.) Cusson is a well-known Chinese medicinal plant, which has been used for the treatment of impotence, frigidity, and skin-related diseases, and exhibits strong antipruritic, antiallergic, antidermatophytic, antibacterial, antifungal, and antiosteoporotic activities. A high-speed counter-current chromatography method was developed for the separation and purification of five bioactive coumarins from this plant. The crude coumarins were obtained by ethanol extraction from the dried fruits of Cnidium monnieri (L.) Cusson under sonication. High-speed counter-current chromatography with the two-phase solvent systems n-hexane-ethyl acetate-ethanol-water (5:5:4:6, v/v) and n-hexane-ethyl acetate-ethanol-water (5:5:6:4, v/v) was successfully performed with stepwise elution. The five relatively pure coumarins were obtained from 500 mg of the crude extract in a single run. Their purities were 90.6-98.9%, and the recoveries were 85.7-94.2%.

Chromatography, High Pressure Liquid↗

PubMed2005

Kinetics of the reduction of chromium(VI) by vitamin C.

The kinetics of the reduction of Cr(VI) to Cr(III) by vitamin C was studied using potassium dichromate solution as the model pollutant. Effects of the concentration of vitamin C, pH, temperature, and irradiation on the reduction of Cr(VI) were examined. The kinetics of Cr(VI) reduction by vitamin C can be described as -d[Cr(VI)]/dt = 0.0156 (microM s(-1).[Cr(VI)][vitamin C] (pH 5), where dt is the differential function (d) of time (t). The activation entropy (deltaS) and enthalpy (deltaH) are 42.4 kJ mol(-1) and -71.0 J mol(-1) K(-1), respectively, and the activation energy at 298 K is 63.5 kJ mol(-1). The advantages of vitamin C as a reductant are as follows: It is an important biological reductant in humans and animals, and it is not toxic. Toxic Cr(VI) can be reduced by vitamin C not only in acidic conditions but also in alkaline solutions (pH 9); furthermore, the reduction was shown to occur both under the irradiation and in the dark. The present results suggest that vitamin C could be used effectively in the remediation of Cr(VI)-contaminated soil and groundwater in a wide range of pH, with or without sunlight.

Ascorbic Acid↗

PubMed2004

Decolorization of dyes and textile wastewater by potassium permanganate.

Decolorization of 10 types of dye solutions by potassium permanganate was studied. Effects of reaction conditions on the decolorization efficiency were examined in batch experiments. The pH value had a significant effect on the decolorization efficiency. When pH value <1.5, the decolorization efficiency was very high. When pH value >4.0, the dye solutions were almost not decolorized. Concentration of potassium permanganate and temperature also showed significant effects on the decolorization efficiency. The decolorization rate of dye solutions by potassium permanganate was rapid, and most of dye solutions can be decolorized effectively. The results of total organic carbon indicated that dye solutions were degraded incompletely by potassium permanganate. The results of treatment of textile wastewater by potassium permanganate indicated that the oxidation with potassium permanganate might be used as a pre-treatment process before biological treatment.

Color↗

PubMed2004

Separation methods used for Scutellaria baicalensis active components.

Scutellaria baicalensis Georgi is one of the most widely used traditional Chinese herbal medicines. Its roots have been used for anti-inflammation, anticancer, antiviral and antibacterial infections of the respiratory and the gastrointestinal tract, cleaning away heat, moistening aridity, purging fire, detoxifying toxicosis, reducing the total cholesterol level and decreasing blood pressures. Baicalin, baicalein, wogonin and oroxylin A are its main active components. This review provides an overview of various separation, detection, and identification techniques employed for the quantitative and qualitative determination of these active components. Applications of high-performance liquid chromatography, high-speed counter-current chromatography, thin layer chromatography, capillary electrophoresis, and micellar electrokinetic capillary chromatography to the separation and determination of these active components are described. Examples of identification of these active components and their metabolites in complex matrices by high-performance liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry are also presented. The advantages and limitations of these separation and identification methods are assessed and discussed.

Chromatography, High Pressure Liquid↗

PubMed2004

Preparative isolation and purification of gastrodin from the Chinese medicinal plant Gastrodia elata by high-speed counter-current chromatography.

Gastrodia elata Blume is a famous Chinese medicinal plant, which has been widely used for the treatment of rheumatism, epilepsy, paralysis, hemiplegia, lumbago, headache and vertigo. High-speed counter-current chromatography was successfully used for the first time for the preparative isolation and purification of the bioactive component gastrodin from G. elata Blume. The crude gastrodin was obtained by extraction with ethanol from the dried roots of G. elata Blume under sonication. Preparative high-speed counter-current chromatography with a two-phase solvent system composed of n-butanol-ethyl acetate-water (2:3:5, v/v/v) was successfully performed yielding 48 mg gastrodin at 96% purity from 500 mg of the crude extract (10.3% gastrodin) with the recovery of approximately 90% in a one-step separation.

Benzyl Alcohols↗

PubMed2004

Preparative isolation and purification of chuanxiongzine from the medicinal plant Ligusticum chuanxiong by high-speed counter-current chromatography.

Ligusticum chuanxiong Hort has been used widely in traditional medicines for the treatment of various kinds of disorders such as cardiovascular and cerebrovascular diseases. High-speed counter-current chromatography was applied to the isolation and purification of the bioactive component chuanxiongzine from L. chuanxiong Hort. The crude chuanxiongzine was obtained by extraction with ethanol from the dried roots of L. chuanxiong Hort under sonication. Preparative high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (5:5:3:7, v/v) was successfully performed yielding 11.5 mg chuanxiongzine at 96.8% purity from 300 mg of the crude extract (4.2% chuanxiongzine) with the recovery of 91% in a one-step separation.

Countercurrent Distribution↗

PubMed2004

Degradation of dyes in aqueous solutions by the Fenton process.

Degradation of 20 different dyes in aqueous solutions by the Fenton process was performed. These dyes include 6 types: acidic, reactive, direct, cationic, disperse and vat dyes. The former four types of dyes were decolorized and their TOC values were decreased greatly, while the color and TOC removals of the latter two types were lower. The catalytic activities of four metal ions on the degradation efficiencies of Vat Blue BO, which was chosen as a model dye because of its lowest color and TOC removals, were compared in the dark and under the ultraviolet light irradiation. The catalytic ability of different metals was Fe2+>Cu2+>Mn2+>Ag+ in the dark, and the same sequence was obtained under irradiation condition with greater degradation efficiency. Furthermore, the efficiencies of three oxidation processes, including H2O2/UV, Fe2+/H2O2 and Fe2+/H2O2/UV were compared. The results showed that the oxidation by Fe2+/H2O2/UV was the strongest, and even greater than the arithmetic sum of the other two processes, which suggests the synergistic effect of ultraviolet and ferrous ions on the degradation reaction.

Catalysis↗

PubMed2004

Reduction of hexavalent chromium by ascorbic acid in aqueous solutions.

Hexavalent chromium is a priority pollutant in the USA and many other countries. Reduction of Cr(VI) to Cr(III) is environmentally favorable as the latter species is not toxic to most living organisms and also has a low mobility and bioavailability. Reduction of Cr(VI) by ascorbic acid (vitamin C) as a reductant was studied using potassium dichromate solution as the model pollutant. Effects of concentration of vitamin C, pH, temperature, irradiation and reaction time on the reduction of Cr(VI) were examined. Cr(VI) might be reduced by vitamin C not only in acidic conditions but also in weakly alkaline solutions. The reduction of Cr(VI) by vitamin C might occur not only under irradiation but also in the dark. Vitamin C is an important biological reductant in humans and animals, and not toxic. It is water-soluble and can easily permeate through various types of soils. The results indicate that vitamin C could be used in effective remediation of Cr(VI)-contaminated soils and groundwater in a wide range of pH, with or without sunlight.

Ascorbic Acid↗

PubMed2002

Isolation and purification of lutein from the microalga Chlorella vulgaris by extraction after saponification.

A simple and efficient method for the isolation and purification of lutein from the microalga Chlorella vulgaris was developed. Crude lutein was obtained by extraction with dichloromethane from the microalga after saponification. Partition values of lutein in the two-phase system of ethanol-water-dichloromethane at different ratios were measured by HPLC so as to assist the determination of an appropriate condition for washing water-soluble impurities in the crude lutein. Partition values of lutein in another two-phase system of ethanol-water-hexane at different ratios were also measured by HPLC for determining the condition for removing fat-soluble impurities. The water-soluble impurities in the crude lutein were removed by washing with 30% aqueous ethanol, and the fat-soluble impurities were removed by extraction with hexane. The final purity of lutein obtained was 90-98%, and the yield was 85-91%.

Chlorella↗