Determination of phenolic profile by HPLC-ESI-MS/MS and antibacterial activity of Eugenia platysema against mollicutes strains

Aim and Objective: Antibiotic resistance is a serious constraint to the development of new effective antibacterials. Therefore, the discovery of the new antibacterials remains one of the main challenges in modern medicinal chemistry. This study was undertaken to identify novel molecules with antibacterial activity. Materials and Methods: Using our unique double-reporter system, in-house large-scale HTS campaign was conducted for the identification of antibacterial potency of small-molecule compounds. The construction allows us to visually assess the underlying mechanism of action. After the initial HTS and rescreen procedure, luciferase assay, C14-test, determination of MIC value and PrestoBlue test were carried out. Results: HTS rounds and rescreen campaign have revealed the antibacterial activity of a series of Nsubstituted triazolo-azetidines and their isosteric derivatives that has not been reported previously. Primary hit-molecule demonstrated a MIC value of 12.5 µg/mL against E. coli Δ tolC with signs of translation blockage and no SOS-response. Translation inhibition (26%, luciferase assay) was achieved at high concentrations up to 160 µg/mL, while no activity was found using C14-test. The compound did not demonstrate cytotoxicity in the PrestoBlue assay against a panel of eukaryotic cells. Within a series of direct structural analogues bearing the same or bioisosteric scaffold, compound 2 was found to have an improved antibacterial potency (MIC=6.25 µg/mL) close to Erythromycin (MIC=2.5-5 µg/mL) against the same strain. In contrast to the parent hit, this compound was more active and selective, and provided a robust IP position. Conclusion: N-substituted triazolo-azetidine scaffold may be used as a versatile starting point for the development of novel active and selective antibacterial compounds.

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Determination of Glutamate and GABA Released by Mouse Embryonic Stem Cells Using HILIC-ESI-MS/MS

The Natural Products Journal ◽

10.2174/2210315509666190211123132 ◽

2020 ◽

Vol 10 (2) ◽

pp. 122-129

Author(s):

Haoyu Lv ◽

Yabin Tang ◽

Fan Sun ◽

Shimin An ◽

Xinjie Yang ◽

...

Keyword(s):

Stem Cells ◽

Embryonic Stem Cells ◽

Embryonic Stem ◽

Mouse Embryonic Stem Cells ◽

Reversed Phase ◽

Water Soluble ◽

Substitution Matrix ◽

Neural Cells ◽

Esi Ms

Background:In recent years, more and more researches have shown that neurotransmitters can also be synthesized and released by peripheral non-neural cells. However, specificity and high sensitivity detection means were required for confirming ESCs autocrine glutamate and γ - aminobutyric acid (GABA). Glutamate and GABA are water-soluble and polar compounds which cannot be retained on a reversed phase C18 column, and their contents are often at a trace level. On the other hand, the biological matrix such as cell culture fluid contains a large number of amino acids, vitamins, carbohydrates, inorganic ions and other substances. Therefore, the main problem is the selection of the chromatographic column to avoid matrix interference.Objective:To establish a rapid and reliable method for the simultaneous determination of glutamate and GABA released from embryonic stem cells based on analytical chemistry.Methods:Glutamate and GABA released from mouse embryonic stem cells were determined on the basis of hydrophilic interaction chromatography coupled with electrospray ionization tandem Mass Spectrometry (HILIC- ESI- MS/MS), using isotope internal standards and substitution matrix method.Results:Undifferentiated embryonic stem cells autocrine glutamate and GABA and will reach releasing- reuptacking dynamic equilibriums at different time points. In contrast, neither glutamate nor GABA releasing could be detected from the MEFs, indicating the specificity release of the mESCs in the applied analytic method.Conclusion:A novel, simple, sensitive, selective and quantitative method was developed for determination of the glutamate and GABA from mouse embryonic stem cells.

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