Two morphotypes versus two chemotypes of Psidium cattleyanum: Chemical and pharmacological comparison and a rational approach for marker selection.

Psidium cattleyanum has two morphotypes: one with yellow fruits and other with red fruits. The leaves are popularly used as anti-inflammatory. However, no distinction is made between the types. Therefore, this study compared chemical and pharmacological data of both morphotypes to select proper biomarkers to ensure P. cattleyanum leaves quality. After extraction optimization by experimental design, 28 samples were analyzed by HPLC. Using Principal Component Analysis, it was possible to detect two chemotypes, unrelated to the color of the fruits. However, the extracts obtained from both chemotypes seemed to play similar anti-inflammatory effect, demonstrated by anti-chemotactic activity. The compounds common to both chemotypes were isolated and identified as hyperoside, miquelianin and quercitrin; these compounds also demonstrated anti-inflammatory potential. Since both chemotypes played similar activity, along with the isolated flavonoids, these flavonoids were selected as biomarkers for quality control of P. cattleyanum leaves. Following ICH guidelines, a HPLC method was validated. In summary, this study demonstrated that hyperoside, miquelianin and quercitrin can be used as biomarkers for quality control of P. cattleyanum leaves and a method was developed and validated to be used interchangeably for both morpho- and chemotypes.

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.