Transmission FTIR derivative spectroscopy for estimation of furosemide in raw material and tablet dosage form

Analyzing macromolecular composition of E. Coli O157:H7 using Raman-stable isotope probing

Metabolic dynamics of bacterial cells is needed for understanding the correlation between changes in environmental conditions and cell metabolic activity. In this study, Raman spectroscopy combined with deuterium labelling was used to analyze the metabolic activity of a single Escherichia coli O157:H7 cell. The incorporation of deuterium from heavy water into cellular biomolecules resulted in the formation of carbon-deuterium (CD) peaks in the Raman spectra, indicating the cell metabolic activity. The broad vibrational peaks corresponding to CD and CH peaks encompassed different specific shifts of macromolecules such as protein, lipids, and nucleic acid. The utilization of tryptophan and oleic acid by the cell as the sole carbon source led to changes in cell lipid composition, as indicated by new peaks in the second derivative spectra. Thus, the proposed method could semi-quantitatively determine total metabolic activity, macromolecule specific identification, and lipid and protein metabolism in a single cell.

Monitoring the effects of chitosan on the profile of certain cell wall and membrane biomolecules in the leaves of Eruca vesicaria ssp. sativa through FT-IR spectroscopy

The present study aimed to investigate the effects of chitosan at different molecular weights on the biomolecule profile of cell walls and membranes in Eruca vesicaria ssp. sativa leaves through FT-IR spectroscopy. It was demonstrated that the chitosan treatments could increase membrane destabilization through the elevation of lipid peroxidation and/or membrane fluidity. However, 10 kDa chitosan at 5 mg L^-1 treatment was estimated to increase membrane lipid production. The 10 and 100 kDa chitosan treatments at 20 mg L^-1 suggested higher protein contents than the other treatments. Chitosan's molecular weight and concentration influenced the relative ratios of functional groups in cell wall lignin. Ten kDa chitosan treatments triggered lignin production better than the other chitosan variants. The results showed that its molecular weight plays a role in the differentiation of chitosan's effects on the biomolecule pattern of E. vesicaria ssp. sativa leaves. However, none of the treatments induced significant changes in the peak positions, indicating that ex vitro chitosan treatment did not induce structural changes in the monitored biomolecules. The results also suggested that 10 kDa chitosan at 5 mg L^-1 could be a better option than the other treatments tested, considering reducing the chemical use and cost in the cultivation process of the plant.

In vitro Fourier transform infrared spectroscopic study of the effect of glycerol on the uptake of beclomethasone dipropionate in living respiratory cells

The quantification of drug in living cells is of increasing interest in pharmaceutical research because of its importance in understanding drug efficacy and toxicity. Label-free in situ measurement methods are advantageous for their ability to obtain chemical and time profiles without the need of labelling or extraction steps. We have previously shown that Fourier transform infrared (FTIR) spectroscopy has the potential to quantify drug in situ within living cells at micromolar level when a simple solution of drug was added to the medium. The purpose of this study was to demonstrate that the approach can evaluate more complex systems such as the effect of membrane modification by a formulation on drug uptakes. The inhaled corticosteroid, beclomethasone dipropionate (BDP), in Calu-3 respiratory epithelial cells in the absence and presence of glycerol, an excipient in some inhaled medicines was used as the model system. The FTIR method was first validated for limit of detection (LOD) and quantification (LOQ) according to published guidelines and the LOQ was found to be ∼ 20 μM, good enough to quantify BDP in the living cell. The uptake of BDP by living Calu-3 cells was found to be reduced in the presence of glycerol as expected due to the stiffening of the cell membrane by the presence of glycerol in the formulation. This study demonstrates the valuable analytical capability of live-cell FTIR to study the effect of formulation on drug transport in lungs and to evaluate drug availability to intracellular targets. We conclude that FTIR has potential to contribute widely at the frontier of live-cell studies.

A chemometric model for the quantitative determination of isotopic impurities in d3-methylamine hydrochloride by Fourier-transform infrared spectroscopy

Deuterated drug molecules are of increasing interest to the pharmaceutical industry due to their capacity to slow metabolism and the potential for improved pharmacokinetics or improved pharmacodynamics they may offer over their non-deuterated counterparts. The desired level of deuteration or isotopic purity is a critical quality attribute for these compounds that can be essential for drug efficacy or patient safety. Deuterated reagents are often used to introduce a deuterated moiety into the drug substance; as such, isotopic impurities in these deuterated input materials need to be tightly controlled. A novel Fourier-transform infrared (FTIR) spectroscopic method was developed and evaluated as a fast and straightforward technique to quantify low-level isotopic impurities in the deuterated reagent d₃-methylamine hydrochloride. Using data acquired through LC-MS analysis, the resulting chemometric model was validated according to ICH Q2(R1) guidelines achieving limits of quantitation of 0.31, 0.31, and 0.34 wt% for d₀-, d₁- and d₂-methylamine hydrochloride impurities respectively.

Co-Amorphous Formulations of Furosemide with Arginine and P-Glycoprotein Inhibitor Drugs

In this study, the amino acid arginine (ARG) and P-glycoprotein (P-gp) inhibitors verapamil hydrochloride (VER), piperine (PIP) and quercetin (QRT) were used as co-formers for co-amorphous mixtures of a Biopharmaceutics classification system (BCS) class IV drug, furosemide (FUR). FUR mixtures with VER, PIP and QRT were prepared by solvent evaporation, and mixtures with ARG were prepared by spray drying in 1:1 and 1:2 molar ratios. The solid-state properties of the mixtures were characterized with X-ray powder diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) in stability studies under different storage conditions. Simultaneous dissolution/permeation studies were conducted in side-by-side diffusion cells with a PAMPA (parallel artificial membrane permeability assay) membrane as a permeation barrier. It was observed with XRPD that ARG, VER and PIP formed co-amorphous mixtures with FUR at both molar ratios. DSC and FTIR revealed single glass transition values for the mixtures (except for FUR:VER 1:2), with the formation of intermolecular interactions between the components, especially salt formation between FUR and ARG. The co-amorphous mixtures were found to be stable for at least two months under an elevated temperature/humidity, except FUR:ARG 1:2, which was sensitive to humidity. The dissolution/permeation studies showed that only the co-amorphous FUR:ARG mixtures were able to enhance both the dissolution and permeation of FUR. Thus, it is concluded that formulating co-amorphous salts with ARG may be a promising option for poorly soluble/permeable FUR.

Polymerization degree of chitosan affects structural and compositional changes in the cell walls, membrane lipids, and proteins in the leaves of Ipomoea purpurea: An FT-IR spectroscopy study

This research aimed to investigate the polymerization degree (DP) -dependent effects of chitosan treatments on structural and compositional changes in certain cell wall polysaccharides (mainly lignin), membrane lipids, and proteins of in vitro-propagated Ipomoea purpurea leaves through FT-IR spectroscopy. The chitosan oligomer mixture (DP 2-15; CHI-OM) and chitosan polymer (DP 70; CHI-P) applied at 5, 10, and 20 mg L^-1 concentrations induced different patterns of biomolecular changes in I. purpurea leaves. The chitosan variants enhanced the destabilization of cell membrane structures. CHI-P treatments increased the lipid structure and protein content of the membranes more than CHI-OM treatments. CHI-OM treatment was found to have the ability to induce the formation of β-sheet structures with a low number of strands, whereas CHI-P treatment was found to have the ability to trigger the formation of more extended α-helix structures in the secondary structure of proteins. CHI-P treatments increased lignin synthesis more than CHI-OM treatments. However, CHI-OM at 10 mg L^-1 concentration was more effective than CHI-P treatments in the induction of cell wall polysaccharide synthesis. These findings suggest that the polymerization degree of chitosan plays a role in changing structures and compositions of the biomolecules present in the leaves of I. purpurea.

Influence of variation in molar ratio on co-amorphous drug-amino acid systems

Molecular interactions were investigated within four different co-amorphous drug-amino acid systems, namely indomethacin-tryptophan (Ind-Trp), furosemide-tryptophan (Fur-Trp), indomethacin-arginine (Ind-Arg) and furosemide-arginine (Fur-Arg). The co-amorphous systems were prepared by ball milling for 90min at different molar ratios and analyzed by XRPD and DSC. Interactions within the co-amorphous samples were evaluated based on the deviation between the actual glass transition temperature (Tg) and the theoretical Tg calculated by the Gordon-Taylor equation. The strongest interactions were observed in the 50mol% drug (1:1M ratio) mixtures, with the exception of co-amorphous Ind-Arg where the interactions within the 40mol% drug samples appear equally strong. A particularly large deviation between the theoretical and actual Tgs was observed within co-amorphous Ind-Arg and Fur-Arg systems. Further analysis of these co-amorphous systems by (13)C solid-state NMR (ssNMR) and FTIR confirmed that Ind and Fur formed a co-amorphous salt together with Arg. A modified approach of using the Gordon-Taylor equation was applied, using the equimolar co-amorphous mixture as one component, to describe the evolution of the Tgs with varying molar ratio between the drug and the amino acid. The actual Tgs for co-amorphous Ind-Trp, Fur-Trp and Fur-Arg were correctly described by this equation, confirming the assumption that the excess component was amorphous forming a homogeneous single component within the co-amorphous mixture without additional interactions. The modified equation described the Tgs of the co-amorphous Ind-Arg with excess Arg less well indicating possible further interactions; however, the FTIR and ssNMR data did not support the presence of additional intermolecular drug-amino acid interactions.