Desenvolvimento e validação de metodologia analítica por CLAE por quantificação de fenólicos em Psidium cattleyanum sabine e avaliação de atividade antiquimiotáxica

Psidium catteyanum Sabine (Mytaceae) é uma espécie nativa brasileira, amplamente conhecida pelo consumo de seu fruto, o araçá, rico em compostos fenólicos. Alguns estudos apontam os flavonoides como os principais constituintes químicos das folhas, e ensaios pré-clínicos demonstram o potencial antioxidante, antimicrobiano e anti-inflamatório que a espécie detém. Com o objetivo de contribuir com parâmetros de qualidade, a otimização da extração de compostos fenólicos e a validação de uma metodologia analítica para quantificação destes foram desenvolvidas. Ainda, foram identificados os compostos majoritários na espécie e testada a atividade antiquimiotáxica dos extratos e isolados. O método de extração por ultrassom foi definido e a metodologia analítica por CLAE para quantificação de quercitrina foi desenvolvida e validada. Foram identificados cinco flavonoides principais na espécie: hiperosídeo, miquelianina, quercetina arabinosídeo, quercetina xilopiranose e quercitrina. Os resultados obtidos permitiram caracterizar dois quimiotipos, sendo que a quercitrina foi o componente majoritário em ambos os tipos. Os teores de quercitrina obtidos nas diferentes amostras variaram de 0.10-1.5% (m/m). A avaliação da atividade antiquimiotáxica demonstrou um potencial anti-inflamatório da espécie, e todas as amostras testadas inibiram significativamente a migração leucocitária nas concentrações de 0.1, 1 e 10 μg/mL, em comparação com o controle negativo.Psidium catteyanum Sabine (Mytaceae) is a native species from Brazil, widely known for the consumption of its fruit, ‘araçá’, rich in phenolic compounds. Some studies point to flavonoids as the main chemical constituents of the leaves, and pre-clinical trials demonstrated the antioxidant, antimicrobial and anti-inflammatory potential that the species detains. In order to contribute to quality parameters, the extraction optimization of phenolic compounds and the validation of an analytical methodology for their quantification were developed. Also, the major compounds in the species were identified and the antichemotactic activity of the extracts and isolates was tested. The ultrasound extraction method was defined and the analytical methodology by HPLC for quantification of quercitrin was developed and validated. Five main flavonoids were identified in the species: hyperoside, miquelianin, quercetin arabinoside, quercetin xylopyranoside and quercitrin. The results obtained allowed to characterize two chemotypes, with quercitrin being the major component in both types. The levels of quercitrin obtained in the different samples varied from 0.10-1.5% (w/w). The evaluation of antichemotactic activity demonstrated an anti-inflammatory potential of the species, and all the tested samples significantly inhibited the leukocyte migration in the concentrations of 0.1, 1 and 10 μg/mL, in comparison with the negative control

Time-kill curves of daptomycin and Monte Carlo simulation for the treatment of bacteraemia caused by Enterococcus faecium

Objectives The aim of this study was to investigate the effect of daptomycin against vancomycin-resistant Enterococcus faecium bacteraemia using computer modelling. Methods Data obtained in vitro from time-kill curves were evaluated by PK/PD modelling and Monte Carlo simulations to determine the logarithmic reduction in the number of colony-forming units (CFU)/mL over 18 days of daptomycin treatment at 6, 8, and 10 mg/kg doses every 24 or 48 h and with variations in creatinine clearance (CLCR) of 15–29, 30–49, and 50–100 mL/min/1.73 m2. Monte Carlo simulations were performed to evaluate the probability of target attainment (PTA) for an area under the unbound drug concentration-time curve/minimum inhibitory concentration (fAUC/MIC) > 36 at the same doses and CLCR. Results Static time-kill model was employed to investigate the antibacterial efficacy of constant daptomycin concentrations. The time-kill curve analysis was performed using mathematical modelling based on a Hill coefficient factor. There was an expressive reduction (> 2 Log CFU/mL) over 18 days of daptomycin treatment in 75th percentile of individuals with CLCR of 15–100 mL/min/1.73 m2) with daptomycin 6–10 mg/kg/day, except for daptomycin every 48 h. Using fAUC/MIC > 36, PTA was > 90% at MICs ≤ 2 μg/mL. Conclusions Higher daptomycin doses were associated with higher mortality in time-kill curves. The simulations indicated that independent of the CLCR the therapeutic responses of VRE occur with doses of daptomycin ≥ 6 mg/kg/day and daptomycin every 48 h is insufficient to treat enterococcal bacteraemia

PK/PD modeling of daptomycin against MRSA and MRSE and Monte Carlo simulation for bacteremia treatment

Objectives The aim of this study was to investigate the effect of daptomycin against methicillin-resistant staphylococci (MRSA and MRSE) bacteremia using computer modeling. Methods A pharmacokinetic/pharmacodynamic (PK/PD) modeling strategy to explain the data from an in vitro dynamic model employing time-kill curves for MRSA and MRSE was proposed. Bacterial killing was followed over time by determining viable counts and the resulting time-kill data was analyzed. Monte Carlo simulations were performed using pharmacokinetic parameters and pharmacodynamic data to determine the probabilities of target attainment and cumulative fractions of response in terms of area under the concentration curve/minimum inhibition concentration (MIC) targets of daptomycin. Simulations were conducted to assess the reduction in the number of colony-forming units (CFU)/mL for 18 days of treatment with daptomycin at doses of 6, 8, and 10 mg/kg/24 h or 48 h with variations in creatinine clearance ( CLCR): 15–29 mL/ min/1.73 m2, 30–49 mL/min/1.73 m2, 50–100 mL/min/1.73 m2, as well as for defining the probability of reaching the target fAUC/MIC = 80 in the same dose and clearance range. A PK/PD model with saturation in the number of bacteria in vitro, growth delay, and bacterial death, as well as Hill’s factor, was used to describe the data for both MRSA and MRSE. Results Monte Carlo simulations showed that for MRSA there was a reduction > 2 log CFU/mL with doses ≥ 6 mg/kg/day in 75th percentile of the simulated population after 18 days of treatment with daptomycin, whereas for MRSE this reduction was observed in 95th percentile of the population. Conclusions The presented in vitro PK/PD model and associated modeling approach were able to characterize the timekill kinetics of MRSA and MRSE. Our study based on PTAs suggests that doses ≥ 6 mg/kg/day of daptomycin should be used to treat bacteremia caused by MRSA and MRSE in patients with CLCR of 15–29 mL/min/1.73 m2. For patients with CLCR ≥ 50 mL/min/1.73 m2, it would be necessary to employ a dose of 10 mg/kg/day to treat complicated bacteremias