Stationary Phase

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Xinmiao Liang - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and chromatographic evaluation of phenyl tetrazole bonded Stationary Phase based on thiol epoxy ring opening reaction
    Journal of Separation Science, 2018
    Co-Authors: Gaowa Jin, Yanming Liu, Fan Yang, Jingyu Yan, Weijia Zhou, Zhimou Guo, Jianhua Zhu, Xinmiao Liang
    Abstract:

    A silica-based reversed-Phase Stationary Phase bonding with phenyl and tetrazole groups was synthesized by thiol-epoxy ring opening reaction. The bonded groups could not only provide hydrophobic interaction, but also π-π, hydrogen bonding, electrostatic interactions, and so on. The results of characterization with elemental analysis and solid-state 13 C cross-polarization magic-angle-spinning NMR spectroscopy indicated the successful preparation of phenyl/tetrazole sulfoether bonded Stationary Phase. Chromatographic evaluation revealed that phenyl/tetrazole sulfoether bonded Stationary Phase behaved well under the reversed-Phase mode. The column parameters (H, S*, A, B, and C) showed different selectivity compared with some typical commercial columns, and it was validated by the separation of estrogen, ginsenoside, alkaloid samples. Based on the different selectivity between phenyl/tetrazole sulfoether bonded Stationary Phase and C18 columns, phenyl/tetrazole sulfoether bonded Stationary Phase also showed potential to construct a 2D reversed-Phase liquid chromatography system with C18. And it was verified by the separation of corydalis tuber and curcuma zedoary extracts.

  • a polyacrylamide based silica Stationary Phase for the separation of carbohydrates using alcohols as the weak eluent in hydrophilic interaction liquid chromatography
    Journal of Chromatography A, 2017
    Co-Authors: Jianfeng Cai, Lingping Cheng, Jianchao Zhao, Yu Jin, Xinmiao Liang
    Abstract:

    Abstract A hydrophilic interaction liquid chromatography (HILIC) Stationary Phase was prepared by a two-step synthesis method, immobilizing polyacrylamide on silica sphere particles. The Stationary Phase (named PA, 5 μm dia) was evaluated using a mixture of carbohydrates in HILIC mode and the column efficiency reached 121,000 N m −1 . The retention behavior of carbohydrates on PA Stationary Phase was investigated with three different organic solvents (acetonitrile, ethanol and methanol) employed as the weak eluent. The strongest hydrophilicity of PA Stationary Phase was observed in both acetonitrile and methanol as the weak eluent, when compared with another two amide Stationary Phases. Attributing to its high hydrophilicity, three oligosaccharides (xylooligosaccharide, fructooligosaccharide and chitooligosaccharides) presented good retention on PA Stationary Phase using alcohols/water as mobile Phase. Finally, PA Stationary Phase was successfully applied for the purification of galactooligosaccharides and saponins of Paris polyphylla . It is feasible to use safer and cheaper alcohols to replace acetonitrile as the weak eluent for green analysis and purification of polar compounds on PA Stationary Phase.

  • a polyvinyl alcohol coated silica gel Stationary Phase for hydrophilic interaction chromatography
    Analyst, 2015
    Co-Authors: Shunli Ji, Feifang Zhang, Xinmiao Liang, Yang Zheng, Bingcheng Yang
    Abstract:

    Multiple layers of polyvinyl alcohol (PVA) coating are generated onto silica gel by thermal immobilization to form a Stationary Phase applied for hydrophilic interaction liquid chromatography (HILIC). It offers an easy way to manipulate the thickness of PVA coating and the obtained Stationary Phase demonstrated high efficiency and high chemical stability.

  • preparation and chromatographic evaluation of a cysteine bonded zwitterionic hydrophilic interaction liquid chromatography Stationary Phase
    Journal of Chromatography A, 2012
    Co-Authors: Aijin Shen, Zhimou Guo, Xiaoming Cai, Xingya Xue, Xinmiao Liang
    Abstract:

    A cysteine-bonded zwitterionic hydrophilic interaction chromatography (hilic) Stationary Phase (click te-cys) was prepared based on the "thiol-ene" click chemistry. the click te-cys material was characterized by solid state c-13 cross polarization/magic-angle spinning (cp/mas) nmr and elemental analysis. the dynamic evaluation for cytosine, cytidine and orotic acid was performed using van deemter plots. the plate height values were no more than 24 mu m for the flow rate between 0.5 and 5.4 mm s(-1) (0.3-3.5 ml min(-1)), which proved the excellent separation efficiency of click te-cys Stationary Phase. the influences of the content of water, concentration of salt and ph of the buffer solution on the retention of model compounds were investigated. the results demonstrated that the separation of polar analytes was dominated by the partitioning mechanism, while the contribution of electrostatic interaction was minor. the thermodynamic characteristic of click te-cys Stationary Phase was also studied according to van't hoff plot. an exothermic process for transferring analytes from the mobile Phase to the Stationary Phase was observed and a linear relationship for ink and 1/t was achieved, indicating no change of retention mechanism within the measured temperature range. besides, the zwitterionic Stationary Phase exhibited good stability. considering the high hydrophilicity of click te-cys Stationary Phase, the application in the separation of protein tryptic digests was carried out using hydrophilic interaction chromatography-electrospray ionization mass spectrometry (hilic-esi-ms). more peaks were adequately resolved on the click te-cys column comparing with that on the tsk amide-80 column. in addition, the orthogonality between hilic and rplc system was investigated utilizing geometric approach. the xterra ms c-18 and click te-cys column displayed great difference in separation selectivity, with the orthogonality reaching 88.0%. on the other hand, the orthogonality between click te-cys and tsk amide-80 system was 21.4%, i.e. the selectivity was similar but slightly different from each other. the successful separation of protein digests indicated the great potential of click te-cys Stationary Phase in the separation of complex samples and applicability in two-dimensional liquid chromatography (2d-lc). (c) 2011 elsevier b.v. all rights reserved.

  • silica based click amino Stationary Phase for ion chromatography and hydrophilic interaction liquid chromatography
    Analyst, 2012
    Co-Authors: Qing Du, Feifang Zhang, Bingcheng Yang, Xinmiao Liang
    Abstract:

    A silica based amino Stationary Phase was prepared by immobilization of propargylamine on azide-silica via click chemistry. This readily prepared click amino Stationary Phase demonstrated good selectivity in separation of common inorganic anions under ion chromatography (IC) mode, and the triazole ring in combination with free amino group was observed to play a major role for separation of the anions examined. On the other hand, the Stationary Phase also showed good hydrophilic interaction liquid chromatography (HILIC) properties in the separation of polar compounds including nucleosides, organic acids and bases. The retention mechanism was found to match well the typical HILIC retention.

Zhimou Guo - One of the best experts on this subject based on the ideXlab platform.

  • synthesis and chromatographic evaluation of phenyl tetrazole bonded Stationary Phase based on thiol epoxy ring opening reaction
    Journal of Separation Science, 2018
    Co-Authors: Gaowa Jin, Yanming Liu, Fan Yang, Jingyu Yan, Weijia Zhou, Zhimou Guo, Jianhua Zhu, Xinmiao Liang
    Abstract:

    A silica-based reversed-Phase Stationary Phase bonding with phenyl and tetrazole groups was synthesized by thiol-epoxy ring opening reaction. The bonded groups could not only provide hydrophobic interaction, but also π-π, hydrogen bonding, electrostatic interactions, and so on. The results of characterization with elemental analysis and solid-state 13 C cross-polarization magic-angle-spinning NMR spectroscopy indicated the successful preparation of phenyl/tetrazole sulfoether bonded Stationary Phase. Chromatographic evaluation revealed that phenyl/tetrazole sulfoether bonded Stationary Phase behaved well under the reversed-Phase mode. The column parameters (H, S*, A, B, and C) showed different selectivity compared with some typical commercial columns, and it was validated by the separation of estrogen, ginsenoside, alkaloid samples. Based on the different selectivity between phenyl/tetrazole sulfoether bonded Stationary Phase and C18 columns, phenyl/tetrazole sulfoether bonded Stationary Phase also showed potential to construct a 2D reversed-Phase liquid chromatography system with C18. And it was verified by the separation of corydalis tuber and curcuma zedoary extracts.

  • preparation and chromatographic evaluation of a cysteine bonded zwitterionic hydrophilic interaction liquid chromatography Stationary Phase
    Journal of Chromatography A, 2012
    Co-Authors: Aijin Shen, Zhimou Guo, Xiaoming Cai, Xingya Xue, Xinmiao Liang
    Abstract:

    A cysteine-bonded zwitterionic hydrophilic interaction chromatography (hilic) Stationary Phase (click te-cys) was prepared based on the "thiol-ene" click chemistry. the click te-cys material was characterized by solid state c-13 cross polarization/magic-angle spinning (cp/mas) nmr and elemental analysis. the dynamic evaluation for cytosine, cytidine and orotic acid was performed using van deemter plots. the plate height values were no more than 24 mu m for the flow rate between 0.5 and 5.4 mm s(-1) (0.3-3.5 ml min(-1)), which proved the excellent separation efficiency of click te-cys Stationary Phase. the influences of the content of water, concentration of salt and ph of the buffer solution on the retention of model compounds were investigated. the results demonstrated that the separation of polar analytes was dominated by the partitioning mechanism, while the contribution of electrostatic interaction was minor. the thermodynamic characteristic of click te-cys Stationary Phase was also studied according to van't hoff plot. an exothermic process for transferring analytes from the mobile Phase to the Stationary Phase was observed and a linear relationship for ink and 1/t was achieved, indicating no change of retention mechanism within the measured temperature range. besides, the zwitterionic Stationary Phase exhibited good stability. considering the high hydrophilicity of click te-cys Stationary Phase, the application in the separation of protein tryptic digests was carried out using hydrophilic interaction chromatography-electrospray ionization mass spectrometry (hilic-esi-ms). more peaks were adequately resolved on the click te-cys column comparing with that on the tsk amide-80 column. in addition, the orthogonality between hilic and rplc system was investigated utilizing geometric approach. the xterra ms c-18 and click te-cys column displayed great difference in separation selectivity, with the orthogonality reaching 88.0%. on the other hand, the orthogonality between click te-cys and tsk amide-80 system was 21.4%, i.e. the selectivity was similar but slightly different from each other. the successful separation of protein digests indicated the great potential of click te-cys Stationary Phase in the separation of complex samples and applicability in two-dimensional liquid chromatography (2d-lc). (c) 2011 elsevier b.v. all rights reserved.

Ying Zhang - One of the best experts on this subject based on the ideXlab platform.

  • botanical medicines with activity against Stationary Phase bartonella henselae
    bioRxiv, 2020
    Co-Authors: Jacob Leone, Sunjya Schweig, Ying Zhang
    Abstract:

    ABSTRACT Bartonella henselae is a Gram-negative, facultative intracellular bacterium which is the causative agent of cat scratch disease. In humans, infections with B. henselae can result in acute or chronic systemic infections with various clinical symptoms including local skin lesions, malaise, aches, chills, lymphadenopathy, endocarditis, or meningoencephalitis. The current treatment for Bartonella infections with antibiotics such as doxycycline and rifampin is not always effective presumably due to bacterial persistence. There have been various anecdotal reports of herbal extracts used for treating patients with persistent Bartonella infections but their activity on B. henselae is unknown. To test the potential antimicrobial activity of botanical or herbal medicines and develop better therapies for persistent Bartonella infections, in this study, we screened an herbal product collection against Stationary Phase B. henselae in vitro using SYBR Green I/ propidium iodide (PI) viability assay. These herbal medicines were selected by the fact that they are commonly used to treat Lyme and co-infections by patients and herbalists, and as a follow-up to our recent study where these herbs were tested against B. burgdorferi. We identified five herbal product extracts that had high activity against Stationary Phase B. henselae at 0.5% (v/v), including Cryptolepis sanguinolenta, Juglans nigra, Polygonum cuspidatum, Scutellaria baicalensis, and Scutellaria barbata. Among them, Cryptolepis sanguinolenta, Juglans nigra, and Polygonum cuspidatum could eradicate all Stationary Phase B. henselae cells within 7 days at 0.25% (v/v) in drug exposure time-kill assay, whereas Scutellaria baicalensis and Scutellaria barbata showed relatively poor activity. The minimum inhibitory concentration (MIC) determination of these top hits indicated they were not only active against Stationary Phase non-growing B. henselae but also had good activity against log Phase growing B. henselae. Our findings may help to develop more effective treatments for persistent Bartonella infections.

  • Identification of essential oils with activity against Stationary Phase Staphylococcus aureus.
    BMC complementary medicine and therapies, 2020
    Co-Authors: Shuzhen Xiao, Peng Cui, Wanliang Shi, Ying Zhang
    Abstract:

    Background Staphylococcus aureus is the most dominant human pathogen, responsible for a variety of chronic and severe infections. There is mounting evidence that persisters are associated with treatment failure and relapse of persistent infections. While some essential oils were reported to have antimicrobial activity against growing S. aureus, activity of essential oils against the Stationary Phase S. aureus enriched in persisters has not been investigated. Methods In this study, we evaluated the activity of 143 essential oils against both growing and Stationary Phase S. aureus by minimum inhibitory concentration (MIC) testing and by colony forming unit assay. Results We identified 39 essential oils (Oregano, Cinnamon bark, Thyme white, Bandit "Thieves", Lemongrass (Cymbopogon flexuosus), Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa, Cinnamon leaf, Clove bud, Citronella, Geranium bourbon, Marjoram, Peppermint, Lemongrass, Cornmint, Elemi, Ho wood, Head ease, Lemon eucalyptus, Litsea cubeba, Myrrh, Parsley seed, Coriander oil, Dillweed, Hyssop, Neroli, Rosewood oil, Tea tree, Cajeput, Clove bud, Lavender, Sleep tight, Vetiver, Palo santo, Sage oil, Yarrow) at 0.5% (v/v) concentration, 10 essential oils (Cinnamon bark, Oregano, Thyme white, Bandit "Thieves", Lemongrass, Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa at 0.25% (v/v) concentration, and 7 essential oils (Oregano, Cinnamon bark, Thyme white, Lemongrass, Allspice, Amyris, Palmarosa at 0.125% (v/v) concentration to have high activity against Stationary Phase S. aureus with no visible growth on agar plates after five-day exposure. Among the 10 essential oils which showed high activity at 0.25% (v/v) concentration, 9 (Oregano, Cinnamon bark, Thyme white, Bandit "Thieves", Lemongrass, Health shield, Allspice, Palmarosa, Amyris showed higher activity than the known persister drug tosufloxacin, while Sandalwood oil had activity at a higher concentration. In Oregano essential oil combination studies with antibiotics, Oregano plus tosufloxacin (or levofloxacin, ciprofloxacin) and rifampin completely eradicated Stationary Phase S. aureus cells, but had no apparent enhancement for linezolid, vancomycin, sulfamethoxazole, trimethoprim, azithromycin or gentamicin. Conclusions Our findings indicate that some essential oils have excellent activity against both growing and Stationary Phase S. aureus. Further studies are needed to identify the active components, evaluate safety, pharmacokinetics, and their activity to eradicate S. aureus infections in vivo.

  • essential oils with high activity against Stationary Phase bartonella henselae
    The Journal of Antibiotics, 2019
    Co-Authors: Wanliang Shi, Ying Zhang
    Abstract:

    Bartonella henselae is a fastidious Gram-negative intracellular bacterium that can cause cat scratch disease, endocarditis in humans and animals, as well as other complications, leading to acute or chronic infections. The current treatment for Bartonella infections is not very effective presumably due to bacterial persistence. To develop better therapies for persistent and chronic Bartonella infections, in this study, with the help of SYBR Green I/PI viability assay, we performed a high-throughput screening of an essential oil library against the Stationary Phase B. henselae. We successfully identified 32 essential oils that had high activity, including four essential oils extracted from Citrus plants, three from Origanum, three from Cinnamomum, two from Pelargonium, and two from Melaleuca, as well as frankincense, ylang-ylang, fir needle, mountain savory (winter), citronella, spearmint, elemi, vetiver, clove bud, allspice, and cedarwood essential oils. The minimal inhibitory concentration (MIC) determination of these 32 top hits indicated they were not only active against Stationary Phase non-growing B. henselae but also had good activity against log-Phase growing B. henselae. The time-kill assay showed 13 active hits, including essential oils of oregano, cinnamon bark, mountain savory (winter), cinnamon leaf, geranium, clove bud, allspice, geranium bourbon, ylang-ylang, citronella, elemi, and vetiver, could eradicate all Stationary Phase B. henselae cells within seven days at the concentration of 0.032% (v/v). Two active ingredients, carvacrol and cinnamaldehyde, of oregano and cinnamon bark essential oils, respectively, were shown to be very active against the Stationary Phase B. henselae such that they were able to eradicate all the bacterial cells even at the concentration ≤ 0.01% (v/v). More studies are needed to identify the active components of some potent essential oils, decode their antimicrobial mechanisms, and evaluate their activity against Bartonella infections in animal models.

  • identification of essential oils with strong activity against Stationary Phase uropathogenic escherichia coli
    Discovery Medicine, 2019
    Co-Authors: Shuzhen Xiao, Peng Cui, Wanliang Shi, Ying Zhang
    Abstract:

    Escherichia coli is the most dominant pathogen causing urinary tract infections (UTIs), but the current most frequently prescribed antibiotics do not always effectively cure the infection due to quiescent persister bacteria, which present a treatment challenge because of frequent relapse. While it has been reported that some essential oils have antimicrobial activity against growing E. coli, the activity of essential oils against the non-growing Stationary Phase E. coli which is enriched in persisters has not been investigated. In this study, we evaluated the activity of 140 essential oils against Stationary Phase uropathogenic E. coli UTI89 and identified 39 essential oils at 0.5% concentration, 8 essential oils at 0.25% concentration, and 3 essential oils at 0.125% concentration to have high activity against Stationary Phase E. coli. Among the top eight essential oils, Oregano showed higher activity than the known persister drug tosufloxacin. The other top four hits including Allspice, Bandit thieves, Cinnamon bark, and Syzygium aromaticum could eradicate Stationary Phase E. coli at a low concentration of 0.25% after three- or five-day exposure, while Health shield, Cinnamon leaf, and Clove bud were found to be active at a higher concentration. In Oregano essential oil drug combination studies with common UTI antibiotics, Oregano plus quinolone drugs (tosufloxacin, levofloxacin, and ciprofloxacin) completely eradicated all Stationary Phase E. coli cells, partially enhanced the activity of nitrofurantoin, but had no apparent enhancement for fosfomycin, meropenem, and cefdinir. Our findings may facilitate the development of more effective treatments for persistent UTIs.

  • Identification of essential oils with activity against Stationary Phase Staphylococcus aureus
    2019
    Co-Authors: Shuzhen Xiao, Peng Cui, Wanliang Shi, Ying Zhang
    Abstract:

    Abstract Staphylococcus aureus is the most dominant human pathogen, responsible for a variety of chronic and severe infections. There is mounting evidence that persisters are associated with treatment failure and relapse of persistent infections. While some essential oils were reported to have antimicrobial activity against growing S. aureus, activity of essential oils against the non-growing Stationary Phase S. aureus enriched in persisters has not been investigated. In this study, we evaluated the activity of 143 essential oils against Stationary Phase S. aureus and identified 39 essential oils (Cinnamon bark, Oregano, Thyme white, Bandit “Thieves”, Lemongrass (Cymbopogon flexuosus), Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa, Cinnamon leaf, Clove bud, Citronella, Geranium bourbon, Marjoram, Peppermint, Lemongrass (Cymbopogon citratus), Cornmint, Elemi, Ho wood, Head ease, Lemon eucalyptus, Litsea cubeba, Myrrh, Parsley seed, Coriander oil, Dillweed, Hyssop, Neroli, Rosewood oil, Tea tree, Cajeput, Glove bud, Lavender, Sleep tight, Vetiver, Palo santo, Sage oil, Yarrow) at 0.5% concentration, 10 essential oils (Cinnamon bark, Oregano, Thyme white, Bandit “Thieves”, Lemongrass (Cymbopogon flexuosus), Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa) at 0.25% concentration, and 7 essential oils (Cinnamon bark, Oregano, Thyme white, Lemongrass (Cymbopogon flexuosus), Allspice, Amyris, Palmarosa) at 0.125% concentration to have high activity against Stationary Phase S. aureus with no visible growth on agar plates after five-day exposure. Among the 10 essential oils which showed high activity at 0.25% concentration, 9 (Cinnamon bark, Oregano, Thyme white, Bandit “Thieves”, Lemongrass (Cymbopogon flexuosus), Health shield, Allspice, Palmarosa, Amyris) showed higher activity than the known persister drug tosufloxacin, while the other one (Sandalwood oil) was found to be active at a higher concentration. In Oregano essential oil drug combination studies with clinical antibiotics, Oregano plus quinolone drugs (tosufloxacin, levofloxacin, ciprofloxacin) and rifampin completely eradicated all Stationary Phase S. aureus cells, but had no apparent enhancement for linezolid, vancomycin, sulfamethoxazole, trimethoprim, azithromycin and gentamicin. Our findings may facilitate development of more effective treatment for persistent S. aureus infections.

Shuzhen Xiao - One of the best experts on this subject based on the ideXlab platform.

  • Identification of essential oils with activity against Stationary Phase Staphylococcus aureus.
    BMC complementary medicine and therapies, 2020
    Co-Authors: Shuzhen Xiao, Peng Cui, Wanliang Shi, Ying Zhang
    Abstract:

    Background Staphylococcus aureus is the most dominant human pathogen, responsible for a variety of chronic and severe infections. There is mounting evidence that persisters are associated with treatment failure and relapse of persistent infections. While some essential oils were reported to have antimicrobial activity against growing S. aureus, activity of essential oils against the Stationary Phase S. aureus enriched in persisters has not been investigated. Methods In this study, we evaluated the activity of 143 essential oils against both growing and Stationary Phase S. aureus by minimum inhibitory concentration (MIC) testing and by colony forming unit assay. Results We identified 39 essential oils (Oregano, Cinnamon bark, Thyme white, Bandit "Thieves", Lemongrass (Cymbopogon flexuosus), Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa, Cinnamon leaf, Clove bud, Citronella, Geranium bourbon, Marjoram, Peppermint, Lemongrass, Cornmint, Elemi, Ho wood, Head ease, Lemon eucalyptus, Litsea cubeba, Myrrh, Parsley seed, Coriander oil, Dillweed, Hyssop, Neroli, Rosewood oil, Tea tree, Cajeput, Clove bud, Lavender, Sleep tight, Vetiver, Palo santo, Sage oil, Yarrow) at 0.5% (v/v) concentration, 10 essential oils (Cinnamon bark, Oregano, Thyme white, Bandit "Thieves", Lemongrass, Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa at 0.25% (v/v) concentration, and 7 essential oils (Oregano, Cinnamon bark, Thyme white, Lemongrass, Allspice, Amyris, Palmarosa at 0.125% (v/v) concentration to have high activity against Stationary Phase S. aureus with no visible growth on agar plates after five-day exposure. Among the 10 essential oils which showed high activity at 0.25% (v/v) concentration, 9 (Oregano, Cinnamon bark, Thyme white, Bandit "Thieves", Lemongrass, Health shield, Allspice, Palmarosa, Amyris showed higher activity than the known persister drug tosufloxacin, while Sandalwood oil had activity at a higher concentration. In Oregano essential oil combination studies with antibiotics, Oregano plus tosufloxacin (or levofloxacin, ciprofloxacin) and rifampin completely eradicated Stationary Phase S. aureus cells, but had no apparent enhancement for linezolid, vancomycin, sulfamethoxazole, trimethoprim, azithromycin or gentamicin. Conclusions Our findings indicate that some essential oils have excellent activity against both growing and Stationary Phase S. aureus. Further studies are needed to identify the active components, evaluate safety, pharmacokinetics, and their activity to eradicate S. aureus infections in vivo.

  • identification of essential oils with strong activity against Stationary Phase uropathogenic escherichia coli
    Discovery Medicine, 2019
    Co-Authors: Shuzhen Xiao, Peng Cui, Wanliang Shi, Ying Zhang
    Abstract:

    Escherichia coli is the most dominant pathogen causing urinary tract infections (UTIs), but the current most frequently prescribed antibiotics do not always effectively cure the infection due to quiescent persister bacteria, which present a treatment challenge because of frequent relapse. While it has been reported that some essential oils have antimicrobial activity against growing E. coli, the activity of essential oils against the non-growing Stationary Phase E. coli which is enriched in persisters has not been investigated. In this study, we evaluated the activity of 140 essential oils against Stationary Phase uropathogenic E. coli UTI89 and identified 39 essential oils at 0.5% concentration, 8 essential oils at 0.25% concentration, and 3 essential oils at 0.125% concentration to have high activity against Stationary Phase E. coli. Among the top eight essential oils, Oregano showed higher activity than the known persister drug tosufloxacin. The other top four hits including Allspice, Bandit thieves, Cinnamon bark, and Syzygium aromaticum could eradicate Stationary Phase E. coli at a low concentration of 0.25% after three- or five-day exposure, while Health shield, Cinnamon leaf, and Clove bud were found to be active at a higher concentration. In Oregano essential oil drug combination studies with common UTI antibiotics, Oregano plus quinolone drugs (tosufloxacin, levofloxacin, and ciprofloxacin) completely eradicated all Stationary Phase E. coli cells, partially enhanced the activity of nitrofurantoin, but had no apparent enhancement for fosfomycin, meropenem, and cefdinir. Our findings may facilitate the development of more effective treatments for persistent UTIs.

  • Identification of essential oils with activity against Stationary Phase Staphylococcus aureus
    2019
    Co-Authors: Shuzhen Xiao, Peng Cui, Wanliang Shi, Ying Zhang
    Abstract:

    Abstract Staphylococcus aureus is the most dominant human pathogen, responsible for a variety of chronic and severe infections. There is mounting evidence that persisters are associated with treatment failure and relapse of persistent infections. While some essential oils were reported to have antimicrobial activity against growing S. aureus, activity of essential oils against the non-growing Stationary Phase S. aureus enriched in persisters has not been investigated. In this study, we evaluated the activity of 143 essential oils against Stationary Phase S. aureus and identified 39 essential oils (Cinnamon bark, Oregano, Thyme white, Bandit “Thieves”, Lemongrass (Cymbopogon flexuosus), Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa, Cinnamon leaf, Clove bud, Citronella, Geranium bourbon, Marjoram, Peppermint, Lemongrass (Cymbopogon citratus), Cornmint, Elemi, Ho wood, Head ease, Lemon eucalyptus, Litsea cubeba, Myrrh, Parsley seed, Coriander oil, Dillweed, Hyssop, Neroli, Rosewood oil, Tea tree, Cajeput, Glove bud, Lavender, Sleep tight, Vetiver, Palo santo, Sage oil, Yarrow) at 0.5% concentration, 10 essential oils (Cinnamon bark, Oregano, Thyme white, Bandit “Thieves”, Lemongrass (Cymbopogon flexuosus), Sandalwood oil, Health shield, Allspice, Amyris, Palmarosa) at 0.25% concentration, and 7 essential oils (Cinnamon bark, Oregano, Thyme white, Lemongrass (Cymbopogon flexuosus), Allspice, Amyris, Palmarosa) at 0.125% concentration to have high activity against Stationary Phase S. aureus with no visible growth on agar plates after five-day exposure. Among the 10 essential oils which showed high activity at 0.25% concentration, 9 (Cinnamon bark, Oregano, Thyme white, Bandit “Thieves”, Lemongrass (Cymbopogon flexuosus), Health shield, Allspice, Palmarosa, Amyris) showed higher activity than the known persister drug tosufloxacin, while the other one (Sandalwood oil) was found to be active at a higher concentration. In Oregano essential oil drug combination studies with clinical antibiotics, Oregano plus quinolone drugs (tosufloxacin, levofloxacin, ciprofloxacin) and rifampin completely eradicated all Stationary Phase S. aureus cells, but had no apparent enhancement for linezolid, vancomycin, sulfamethoxazole, trimethoprim, azithromycin and gentamicin. Our findings may facilitate development of more effective treatment for persistent S. aureus infections.

  • identification of essential oils with strong activity against Stationary Phase uropathogenic escherichia coli
    bioRxiv, 2019
    Co-Authors: Shuzhen Xiao, Peng Cui, Wanliang Shi, Ying Zhang
    Abstract:

    Abstract Escherichia coli is the most dominant pathogen causing urinary tract infections (UTIs), but the current most frequently prescribed antibiotics do not always effectively cure the infection due to quiescent persister bacteria. While it has been reported that some essential oils have antimicrobial activity against growing E. coli, the activity of essential oils against the non-growing Stationary Phase E. coli which is enriched in persisters has not been investigated. We evaluated the activity of 140 essential oils against Stationary Phase uropathogenic E. coli UTI89 and identified 39, 8 and 3 essential oils at 0.5%, 0.25% and 0.125% concentrations to have high activity against Stationary Phase E. coli. Among the top eight essential oils, Oregano showed higher activity than the known persister drug tosufloxacin. The other top seven hits included Allspice, Bandit "Thieves", Cinnamon bark, Syzygium aromaticum, Health shield, Cinnamon leaf and Clove bud. In Oregano essential oil drug combination studies with common UTI antibiotics, Oregano plus quinolone drugs (tosufloxacin, levofloxacin, ciprofloxacin) completely eradicated all Stationary Phase E. coli cells, partially enhanced the activity of nitrofurantoin, but had no apparent enhancement for fosfomycin, meropenem and cefdinir. Our findings may facilitate development of more effective treatments for persistent UTIs.

  • Identification of FDA-Approved Drugs with Activity against Stationary Phase Bartonella henselae
    MDPI AG, 2019
    Co-Authors: Jie Feng, Shuzhen Xiao, Wanliang Shi, David Sullivan, Ying Zhang
    Abstract:

    Bartonella henselae can cause various infections in humans, ranging from benign and self-limiting diseases to severe and life-threatening diseases as well as persistent infections that are difficult to treat. To develop more effective treatments for persistent Bartonella infections, in this study, we performed a high-throughput screen of an FDA-approved drug library against Stationary Phase B. henselae using the SYBR Green I/propidium iodide (PI) viability assay. We identified 110 drug candidates that had better activity against Stationary Phase B. henselae than ciprofloxacin, and among the top 52 drug candidates tested, 41 drugs were confirmed by microscopy to have higher activity than the current frontline antibiotic erythromycin. The identified top drug candidates include pyrvinium pamoate, daptomycin, methylene blue, azole drugs (clotrimazole, miconazole, sulconazole, econazole, oxiconazole, butoconazole, bifonazole), aminoglycosides (gentamicin and streptomycin, amikacin, kanamycin), amifostine (Ethyol), antiviral Lopinavir/ritonavir, colistin, nitroxoline, nitrofurantoin, verteporfin, pentamidine, berberine, aprepitant, olsalazine, clinafloxacin, and clofoctol. Pyrvinium pamoate, daptomycin, methylene blue, clotrimazole, and gentamicin and streptomycin at their respective maximum drug concentration in serum (Cmax) had the capacity to completely eradicate Stationary Phase B. henselae after 3-day drug exposure in subculture studies. While the currently used drugs for treating bartonellosis, including rifampin, erythromycin, azithromycin, doxycycline, and ciprofloxacin, had very low minimal inhibitory concentration (MIC) against growing B. henselae, they had relatively poor activity against Stationary Phase B. henselae, except aminoglycosides. The identified FDA-approved agents with activity against Stationary Phase B. henselae should facilitate development of more effective treatments for persistent Bartonella infections

Liang Zhao - One of the best experts on this subject based on the ideXlab platform.

  • a phenylenediamine based carbon dot modified silica Stationary Phase for hydrophilic interaction chromatography
    Analyst, 2020
    Co-Authors: Yali Yang, Haijuan Zhang, Jia Chen, Zhan Li, Liang Zhao
    Abstract:

    Red emitting carbon dots derived from p-phenylenediamine (PPDCDs) were successfully prepared and grafted onto the surface of silica spheres, which served as a new Stationary Phase (Sil-PPDCDs) for liquid chromatography with excellent hydrophilic selectivity. Various hydrophilic analytes including nucleosides and bases, amino acids, saccharides and ginsenosides can be well separated on this Stationary Phase. Compared with the precursor-modified silica, i.e. p-phenylenediamine functionalized silica Stationary Phase (Sil-PPD), Sil-PPDCDs possessed enhanced selectivity for the separation of tested polar compounds. Moreover, compared with two commercially available hydrophilic columns, the selective behavior of the Stationary Phase was also considerable. The successful application of the Sil-PPDCDs Stationary Phase again indicated the great potential of carbon dots as a new modifier of the Stationary Phase in high performance liquid chromatography, and this kind of new Stationary Phase is very promising to be used for the separation of hydrophilic compounds in biochemical and pharmaceutical analysis.

  • preparation and chromatographic performance of a multifunctional immobilized chiral Stationary Phase based on dialdehyde microcrystalline cellulose derivatives
    Chirality, 2019
    Co-Authors: Lixiao Chen, Shuqing Dong, Qi Wu, Hui Li, Fang Yang, Liang Zhao
    Abstract:

    : A novel high-performance liquid chromatography (HPLC) multifunctional immobilized chiral Stationary Phase was prepared by bonding dialdehyde microcrystalline cellulose to aminosilica via Schiff base reaction and then derivatized with 3,5-dimethylphenyl isocyanate. The HPLC multifunctional immobilized chiral Stationary Phase could not only achieve chiral separation but also achieve achiral separation. Chiral separation evaluation showed that 1-(1-naphthyl)ethanol and mandelonitrile got separation in normal Phase (NP) mode. Ranolazine, benzoin ethyl ether, metalaxyl, and diclofop were successfully separated in reversed Phase (RP) mode. Aromatic compounds such as polycyclic aromatic hydrocarbons (PAHs), anilines, and aromatic acids were selected as analytes to investigate the achiral separation performance of the multifunctional immobilized chiral Stationary Phase in NP and RP modes. The achiral separation evaluation showed that six PAHs could get good separation within 10 minutes in NP mode. Four aromatic acids were well separated in RP mode. The retention mechanism of aromatic compounds on the Stationary Phase was discussed, founding that π-π interaction, π-π electron-donor-acceptor (EDA) interaction, and hydrogen bonding interaction played important roles during the achiral separation process. This multifunctional immobilized chiral Stationary Phase had the advantages of simple bonding steps, short reaction time, and no need for space arm.

  • chromatographic evaluation of octadecyl bonded sio2 sio2 based Stationary Phase for reversed Phase high performance liquid chromatography
    Journal of Inorganic and Organometallic Polymers and Materials, 2013
    Co-Authors: Xia Zhang, Shuqing Dong, Qin Liu, Litao Wang, Zhixin Zhang, Xiaoli Zhang, Liang Zhao
    Abstract:

    A new type of octadecyl-bonded SiO2/SiO2 (ODSS) core–shell monodisperse silica spheres was prepared as a high performance liquid chromatography Stationary Phase. The chromatographic performance was evaluated and compared with totally porous octadecyl-bonded SiO2. Various methods were used for characterization of the two column packings for reversed-Phase chromatography in terms of permeability, hydrophobic selectivity, sensitivity, stability and hydrophobicity. The results showed that the ODSS-based Stationary Phase has enhanced permeability, good hydrophobic selectivity, high chemical stability and sensitivity. Acidic, basic and neutral aromatic compounds were separated on the two types of Stationary Phases. The ODSS-based Stationary Phase has good selectivity and gives symmetrical narrow peaks under reversed-Phase conditions.

  • preparation and characterization of sio2 sio2 core shell microspheres as rp hplc Stationary Phase
    Journal of Inorganic and Organometallic Polymers and Materials, 2011
    Co-Authors: Qin Liu, Shuqing Dong, Zh.x. Zhang, Litao Wang, Liang Zhao
    Abstract:

    Novel SiO2/SiO2 core–shell monodisperse silica spheres for high-performance liquid chromatography packing materials are prepared by the layer-by-layer self-assembly technique. The core–shell silica spheres consist of micrometer-sized porous silica spheres as the core and a thin mesoporous silica shell formed from multilayer nanometer-sized silica particles. In addition, a reversed-Phase packing by bonding octadecyltrichlorosilane on SiO2/SiO2 particles through alkyl-modified method is prepared and characterized. The results show that the carbon content of the new reversed-Phase Stationary Phase increases by approximately 45% compared with the uncoated octadecyl-bonded SiO2 Stationary Phase. Eight kinds of tested aromatic compounds are well-separated on the packing and the peaks are symmetrical, which demonstrates that the packing acts as an excellent reversed-Phase chromatographic Stationary Phase.