Determination and haemolytic activity of saponins in hairy root culture of Platycodon grandiforum A.DC

S u m m a r y The sum of saponins in the hairy root lines (6, 17) of Platycodon grandiforum A.DC. was compared. Hairy root line 6 showed a higher total saponin content (6.92%) than the line 17 (6.01%). According to the Chinese Pharmacopoeia standards the content of saponins in Platycodi Radix should be not less than 2%. Our results seem to indicate that the hairy root culture of Platycodon grandiforum A.DC. is a good source of saponins. The Haemolytic 104 N. Urbańska, J. Nartowska, A. Skorupska, D. Ruszkowski, J. Giebułtowicz, O. Olszowska Index of the hairy root line 6 was 1600. Digitonin was used as a reference. Moreover, the haemolytic activity of TLC subfractions of saponins varied

The use of near-infrared as process analytical technology (PAT) during 3D printing tablets at the point-of-care

Fused deposition modelling (FDM) is one of the most researched 3D printing technologies that holds great potential for low-cost manufacturing of personalised medicine. To achieve real-time release, timely quality control is a major challenge for applying 3D printing technologies as a point-of-care (PoC) manufacturing approach. This work proposes the use of a low-cost and compact near-infrared (NIR) spectroscopy modality as a process analytical technology (PAT) to monitor a critical quality attribute (drug content) during and after FDM 3D printing process. 3D printed caffeine tablets were used to manifest the feasibility of the NIR model as a quantitative analytical procedure and dose verification method. Caffeine tablets (0–40 % w/w) were fabricated using polyvinyl alcohol and FDM 3D printing. The predictive performance of the NIR model was demonstrated in linearity (correlation coefficient, R2) and accuracy (root mean square error of prediction, RMSEP). The actual drug content values were determined using the reference high-performance liquid chromatography (HPLC) method. The model of full-completion caffeine tablets demonstrated linearity (R2 = 0.985) and accuracy (RMSEP = 1.4 %), indicated to be an alternative dose quantitation method for 3D printed products. The ability of the models to assess caffeine contents during the 3D printing process could not be accurately achieved using the model built with complete tablets. Instead, by building a predictive model for each completion stage of 20 %, 40 %, 60 % and 80 %, the model of different completion caffeine tablets displayed linearity (R2 of 0.991, 0.99, 0.987, and 0.983) and accuracy (RMSEP of 2.22 %, 1.65 %, 1.41 %, 0.83 %), respectively. Overall, this study demonstrated the feasibility of a low-cost NIR model as a non-destructive, compact, and rapid analysis dose verification method enabling the real-time release to facilitate 3D printing medicine production in the clinic

Monte Carlo simulation of Heisenberg spin glass on FCC lattice in external magnetic field

The simple but realistic model described by a Heisenberg Hamiltonian with nearest neighbours and next nearest neighbours interactions in an external magnetic field was investigated by use of the Monte Carlo method. Three-dimensional vector spins of length View the MathML source were distributed randomly on a fcc lattice. Different concentrations of spins, x = 0.05, 0.10,…,0.90, were studied. For low concentrations, simulated samples contained about 1000 spins. For higher values of x the size of system was about 8000. All the computations were done for high external magnetic fields of around 3 T. During simulation, physical quantities such as magnetization, energy, specific heat and magnetic susceptibility were determined. The results for magnetization differ for the zero-field-cooled (ZFC) and field-cooled (FC) cases for the whole range of concentrations. This difference, also typical for experimental data, seems to vanish after longer simulation. From critical temperatures for computer simulated magnetization, the magnetic phase diagram was obtained and compared to experimental data for Cd1-xMnxTe. Concentration dependent results for magnetization, specific heat and magnetic susceptibility allowed one to distinguish three different regions for the simulated system: x ≤ 0.20, 0.30 ≤ x ≤ 0.60, 0.70 ≤ x ≤ 0.90

Replicates Number for Drug Stability Testing during Bioanalytical Method Validation—An Experimental and Retrospective Approach

Background: The stability of a drug or metabolites in biological matrices is an essential part of bioanalytical method validation, but the justification of its sample size (replicates number) is insufficient. The international guidelines differ in recommended sample size to study stability from no recommendation to at least three quality control samples. Testing of three samples may lead to results biased by a single outlier. We aimed to evaluate the optimal sample size for stability testing based on 90% confidence intervals. Methods: We conducted the experimental, retrospective (264 confidence intervals for the stability of nine drugs during regulatory bioanalytical method validation), and theoretical (mathematical) studies. We generated experimental stability data (40 confidence intervals) for two analytes—tramadol and its major metabolite (O-desmethyl-tramadol)—in two concentrations, two storage conditions, and in five sample sizes (n = 3, 4, 5, 6, or 8). Results: The 90% confidence intervals were wider for low than for high concentrations in 18 out of 20 cases. For n = 5 each stability test passed, and the width of the confidence intervals was below 20%. The results of the retrospective study and the theoretical analysis supported the experimental observations that five or six repetitions ensure that confidence intervals fall within 85–115% acceptance criteria. Conclusions: Five repetitions are optimal for the assessment of analyte stability. We hope to initiate discussion and stimulate further research on the sample size for stability testing

An example of the application of Mössbauer spectroscopy for determination of concentration of iron in lyophilized brain tissue

Mössbauer spectroscopy is not routinely used for the determination of the concentration of iron. However, as this method does not need any pre-treatment of samples before measurements, it may be of extreme importance for the assessment of iron in samples, which can then be used for further investigations. Biological samples are a good example, however, as the concentrations of iron are very low in these, it is important to exclude possible artefacts from the background spectrum related to iron present in the counter and cryostat windows. The aim of this study was to compare two methods of determination of the amounts of iron in investigated sample: one, in which the background spectrum was subtracted from the sample spectrum measured, and the other, in which the obtained non-elaborated spectrum was fitted with two doublets – a doublet for the measured sample and a doublet for the background spectrum. Three samples containing known amounts of natural iron (400, 800 and 1600 µg) and a sample of lyophilized human brain tissue obtained from globus pallidus were assessed. Both methods led to the creation of a very good calibration curve with a correlation coefficient of 0.99. Although both methods gave similar results for the concentration of iron in the sample, the subtraction of the background spectrum had a significantly lower error of the final result