Proposal of an HPLC/UV/FLD Screening Method for the Simultaneous Determination of Ten Antibiotics in Environmental Waters.

An HPLC-UV/FLD method for simultaneous detection of ten antibiotics in surface waters was developed. Antibiotics were extracted from water using solid phase extraction. An Atlantis T3 column was used with acetonitrile and 0.05% trifluoroacetic acid as a mobile phase for separation, with a total running time of 45 min. Signal detection was performed at 280 nm; fluoroquinolones were additionally quantified by fluorescence detection. Validation parameters such as linearity, recovery and precision were evaluated. The limits of detection (LOD) in river waters were in the range 0.1-1.3 µg/L for antibiotics detected by UV, and 0.039 and 0.073 µg/Lfor fluoroquinolones detected by FLD. LOD are sufficiently low to consider this method as a first alternative for HPLC-MS methods that will allow alerting for the presence of antibiotics in surface waters. This screening method is rapid, sensitive, reproducible and economical.

A new RP-HPLC method as an auxiliary tool for optimization of sample preparation procedures for tracing of PPCPs of different hydrophilicities.

Recently, pharmaceutical and personal care products (PPCPs) have received considerable attention because of their increasing use. Analysis of PPCPs presents a significant analytical challenge, with high-performance liquid chromatography (HPLC) in reversed-phase mode, as the most widely used analytical technique. To facilitate the optimization of the procedures that are applied in the early stages of sample preparation, a simple and fast HPLC method is proposed in this work for the separation of some PPCPs with a wide range of hydrophilicity. Two columns were evaluated (Atlantis dC18 and Discovery HS F5); as for mobile phases: a formate buffer (40 mmol L-1, pH 4) and methanol were tested in a gradient mode. The fluorinated column allowed better separation in a shorter time and better resolution for all analytes (Rs > 1). The proposed method delivered good performance for the tracing of PPCPs and is a suitable alternative to traditional C18-based HPLC methods.

HPLC Method Validation for Jatropha dioica Extracts Analysis.

Jatropha dioica is a popular plant used in Mexican herbal medicine to treat several diseases. Cytotoxicity, antimicrobial and antiviral activities have been reported for root extracts, while riolozatrione, 6-epi-riolozatrione, citlalitrione and jatrophatrione, among others, have been identified as the principal components. In this work, an HPLC/DAD method for the analysis of riolozatrione and other major compounds in extracts of different polarities was validated. The analysis was carried out on an AccQ-Tag column with a water-acetonitrile mixture as mobile phase. Flow rate was 0.2 mL/min, and the separation was carried out in gradient mode with UV detection set at 254 nm. The resulting method showed good reproducibility in both retention times and peak areas of riolozatrione, 6-epi-riolozatrione, citlalitrione and jatrophatrione, with relative standard variations lower than 4.5 and 10.5% respectively. In addition, this method provides a good performance for riolozatrione quantitation, with recoveries between 102 and 108% and RSDs lower than 2.5%. The polarity of the extracting solvent did not affect the performance of the chromatographic method. The developed method was applied for the analysis and quantification of riolozatrione in extracts of Jatropha dioica collected in several seasonal stages and years (2014-2017).

In Vivo Activity of the Benzothiazinones PBTZ169 and BTZ043 against Nocardia brasiliensis.

BACKGROUND: Mycetoma is a neglected, chronic, and deforming infectious disease caused by fungi and actinomycetes. In Mexico, N. brasiliensis is the predominant etiologic agent. Therapeutic alternatives are necessary because the current drug regimens have several disadvantages. Benzothiazinones (BTZ) are a new class of candidate drugs that inhibit decaprenyl-phosphoribose-epimerase (DprE1), an essential enzyme involved in the cell wall biosynthesis of Corynebacterineae. METHODOLOGY/PRINCIPAL FINDINGS: In this study, the in vitro activity of the next generation BTZ, PBTZ169, was tested against thirty Nocardia brasiliensis isolates. The MIC50 and MIC90 values for PBTZ169 were 0.0075 and 0.03 µg/mL, respectively. Because Nocardia is a potential intracellular bacterium, a THP-1 macrophage monolayer was infected with N. brasiliensis HUJEG-1 and then treated with PBTZ169, resulting in a decrease in the number of colony-forming units (CFUs) at a concentration of 0.25X the in vitro value. The in vivo activity was evaluated after infecting female BALB/c mice in the right hind food-pad. After 6 weeks, treatment was initiated with PBTZ169 and its activity was compared with the first generation compound, BTZ043. Both BTZ compounds were administered at 100 mg/kg twice daily by gavage, and sulfamethoxazole/trimethoprim (SXT), at 100 mg/kg sulfamethoxazole, was used as a positive control. After 22 weeks of therapy, only PBTZ169 and SXT displayed statistically significant activity. CONCLUSION: These results indicate that DprE1 inhibitors may be useful for treating infections of Nocardia and may therefore be active against other actinomycetoma agents. We must test combinations of these compounds with other antimicrobial agents, such as linezolid, tedizolid or SXT, that have good to excellent in vivo activity, as well as new DprE1 inhibitors that can achieve higher plasma levels.

Intracellular activity of tedizolid phosphate and ACH-702 versus Mycobacterium tuberculosis infected macrophages.

BACKGROUND: Due to the emergency of multidrug-resistant strains of Mycobacterium tuberculosis, is necessary the evaluation of new compounds. FINDINGS: Tedizolid, a novel oxazolidinone, and ACH-702, a new isothiazoloquinolone, were tested against M. tuberculosis infected THP-1 macrophages. These two compounds significantly decreased the number of intracellular mycobacteria at 0.25X, 1X, 4X and 16X the MIC value. The drugs were tested either in nanoparticules or in free solution. CONCLUSION: Tedizolid and ACH-702 have a good intracellular killing activity comparable to that of rifampin or moxifloxacin.

HPLC method for the simultaneous analysis of fluoroquinolones and oxazolidinones in plasma.

A chromatographic method was implemented and validated for the simultaneous determination of antimicrobials proposed for the treatment of mycetoma: three fluoroquinolones: ciprofloxacin, moxifloxacin and sparfloxacin; two oxazolidinones: DA-7157 (DA2; torezolid) and its prodrug DA-7218 (DA1). Separation of analytes was achieved on an Atlantis dC18 column (150 × 4.6 mm i.d., 5 µm particle size) with a mobile phase composed of acetonitrile and trifluoroacetic acid 0.1% (v/v) using a gradient program. Total running time was 30 min. Quantification of sparfloxacin was carried out using a DAD at 278 nm; the oxazolidinones DA1 and DA2 and the quinolones ciprofloxacin and moxifloxacin were analyzed by fluorescence with an excitation wavelength of 292 nm and an emission wavelength of 525 nm. Intraday precision was in the range of 3.2 and 14.1%. Linearity range was from 0.3 to 10 µg/mL for sparfloxacin using DAD detector, and from 0.2 to 10 µg/mL for ciprofloxacin, 0.3 to 10 µg/mL for DA2, 0.4 to 10 µg/mL for DA1 and 0.04 to 10 µg/mL for moxifloxacin with fluorescence detector. Acetonitrile was used to precipitate proteins from plasma. Recoveries at low, medium and high concentration were between 80 and 120%. Limits of quantification were between 0.04 and 0.4 µg/mL in plasma. The method can be applied for individual or simultaneous determination of the antimicrobials in plasma.

Efficacy of ciprofloxacin and moxifloxacin against Nocardia brasiliensis in vitro and in an experimental model of actinomycetoma in BALB/c mice.

The efficacy of ciprofloxacin and moxifloxacin against Nocardia brasiliensis was evaluated by applying 25 mg of each drug/kg subcutaneously every 8 h in BALB/c mice infected with N. brasiliensis. A statistically significant difference was observed only with moxifloxacin. A moxifloxacin-trimethoprim-sulfamethoxazole combination was as active as when each compound was used alone.

Efficacy of DA-7218, a new oxazolidinone prodrug, in the treatment of experimental actinomycetoma produced by Nocardia brasiliensis.

Two recently synthesized oxazolidinones: (R)-3-(4-(2-(2-methyltetrazol-5-yl)-pyridin-5-yl)-3-fluorophenyl)-5-hydroxymethyloxazolidin-2-one (DA-7157) and its corresponding pro-drug (R)-3-(4-(2-(2-methyltetrazol-5-yl)-pyridin-5-yl)-3-fluorophenyl)-2-oxo-5-oxazolidinyl) methyl disodium phosphate (DA-7218), have shown very good activity against several Gram positive bacteria, including Nocardia and Mycobacterium. In the present work we evaluated the therapeutic in vivo effects of DA-7218 on Nocardia brasiliensis. We first determined the plasma concentration of the prodrug in BALB/c mice using several doses and then tested its activity in an in vivo experimental actinomycetoma murine model. At the end of treatment, there was a statistically significant difference between the three drug receiving groups (25, 12.5 and 5 mg/kg) and the control group(saline solution) (p=0.001), proving that DA-7218 is effective for the treatment of experimental murine actinomycetoma. This compound could be a potential option for patients affected with mycetoma by Nocardia brasiliensis.

Comparison of high-performance liquid chromatographic and thin-layer chromatographic methods for determination of aloin in herbal products containing Aloe vera.

Aloe vera is a medicinal plant used worldwide to treat a variety of conditions and, as such, has important commercial value. Aloin is a principal component of aloe vera leaves and is used for quality control of products containing it. A semiquantitative thin-layer chromatographic (TLC) method for determining the concentration of aloin in aloe-based products was validated. The results were similar to those of a validated high-performance liquid chromatographic method; therefore, TLC, which is a simple, sensitive, specific, rapid, and cheap method, may be ideal for use in any laboratory for routine analysis of commercial products containing aloe vera.

Simultaneous determination and validation of antimicrobials in plasma and tissue of actinomycetoma by high-performance liquid chromatography with diode array and fluorescence detection.

A simple, precise, and reliable chromatographic method was developed for the simultaneous determination in plasma and infected tissue of five antimicrobials proposed for the treatment of actinomycotic mycetoma: amoxicillin, trimethoprim, linezolid, sulfamethoxazole and garenoxacin. Separation of the analytes was achieved on an Atlantis dC18 column (150 mm x 4.6 mm, ID 5 microm) with a mobile phase composed of acetonitrile and trifluoroacetic acid (ATF) 0.1% (v/v) using a gradient program. The detection was carried out using a diode array detector at 254 nm and in a fluorescence detector at wavelengths of excitation and emission of 292 nm and 392 nm for linezolid and sulfamethoxazole, and 292 nm and 408 nm for garenoxacin, respectively. The intraday precision was in the range of 0.7-15% of relative standard deviations (%R.S.D.) for plasma and 1-18% for tissue. Linearity range was from 2.4 to 20 microg/ml for amoxicillin, 0.3 to 20 microg/ml for trimethoprim, sulfamethoxazole and linezolid, and 0.3 to 10 microg/ml for garenoxacin. Acetonitrile was used to precipitate proteins from plasma. Recoveries in plasma ranged from 71% to 118% and in infected tissue from 78% to 122%. Limits of detection (LODs) were 1.2 and 0.5 microg/ml for amoxicillin in plasma and tissue, respectively and 0.15 and 1.2 microg/ml in plasma and tissue, respectively for the other antimicrobials. The method can be applied for individual or simultaneous determination of the antimicrobials in plasma and tissue of mouse infected with actinomycetoma.