Improved achiral and chiral hplc-uv analysis of ruxolitinib in two different drug formulations

In this paper, two new reversed-phase (RP) HPLC-UV methods enabling the quantitative achiral and chiral analysis of ruxolitinib in commercial tablets (containing 20 mg of active pharmaceutical ingredient, API) and not commercially available galenic capsules (with 5 mg of API) are described. For the achiral method based on the use of a water/acetonitrile [70:30, v/v; with 0.1% (v) formic acid] eluent, a “research validation” study was performed mostly following the “International Council for Harmonization” guidelines. All the system suitability parameters were within the acceptance criteria: tailing factor, between 1.7 and 2.0; retention factor, 2.2; number of theoretical plates, >9000. The linearity curve showed R2 = 0.99 (Rxv2 = 0.99), while trueness (expressed as recovery) was between 96.3 and 106.3%. Coefficient of variations (CVs) (repeatability: CVw and intermediate precision: CVIP ) did not exceed 1.3% and 2.9%, respectively. Moreover, the use of the enantiomeric Whelk-O1 chiral stationary phases operated under similar RP eluent conditions as for the achiral analyses, and the “inverted chirality columns approach (ICCA)” allowed us to establish that the enantiomeric purity of ruxolitinib is retained upon reformulation from tablets to capsules. The two developed methods can allow accurate determinations of ruxolitinib in drug formulations for medical use

Original enantioseparation of illicit fentanyls with cellulose-based chiral stationary phases under polar-ionic conditions

Fentanyl analogues used in therapy and a range of highly potent non-pharmaceutical fentanyl derivatives are subject to international control, as the latter are increasingly being synthesized illicitly and sold as ‘synthetic heroin’, or mixed with heroin. A significant number of hospitalizations and deaths have been reported in the EU and USA following the use of illicitly synthesized fentanyl derivatives. It has been unequivocally demonstrated that the enantiomers of fentanyl derivatives exhibit different pharmaco-toxicological profiles, which makes crucial to avail of suitable analytical methods enabling investigations at a “stereochemical level”. Chromatographic methods useful to discriminate the enantioseparation of fentanyls and their derivatives are still missing in the literature. This is the first study in which the enantioseparation of four fentanyl derivatives, that is, (±)-trans-3-methyl norfentanyl, (±)-cis-3-methyl norfentanyl, β-hydroxyfentanyl, and β-hydroxythiofentanyl, has been obtained under polar-ionic conditions. Indeed, the use of ACN-based mobile phases with minor amounts of either 2-propanol or ethanol (plus diethylamine and formic acid as ionic additives) allowed obtaining enantioseparation and enantioresolution factors up to 1.83 and 7.02, respectively. For the study, the two chiral stationary phases cellulose tris(3-chloro-4-methylphenylcarbamate) and cellulose tris(4-chloro-3-methylphenylcarbamate) were used, displaying a remarkably different performance towards the enantioseparation of (±)-cis-3-methyl norfentanyl. Chiral LC analyses with a high-resolution mass spectrometry detector were also carried out in order to confirm the obtained data and demonstrate the suitability and compatibility of the optimized mobile phases with mass spectrometric systems

Efficient enantioresolution of aromatic α-hydroxy acids with Cinchona alkaloid-based zwitterionic stationary phases and volatile polar-ionic eluents

Single enantiomers of mandelic acid (1), 3-phenyllactic acid (2), and 3-(4-hydroxyphenyl)lactic acid (3) are the subject of many fields of investigation, spanning from the pharmaceutical synthesis to that of biocompatible and biodegradable polymers, while passing from the interest towards their antimicrobial activity to their role as biomarkers of particular pathological conditions or occupational exposures to specific xenobiotics. All above mentioned issues justify the need for accurate analytical methods enabling the correct determination of the individual enantiomers. So far, all the developed liquid chromatography (LC) methods were not or hardly compatible with mass spectrometry (MS) detection. In this paper, a commercially available Cinchona-alkaloid derivative zwitterionic chiral stationary phase [that is, the CHIRALPAK® ZWIX(−)] was successfully used to optimize the enantioresolution of compounds 1–3 under polar-ionic (PI) conditions with a mobile phase consisting of an acetonitrile/methanol 95/5 (v/v) mixture with 80 mM formic acid. With the optimized conditions, enantioseparation and enantioresolution values up to 1.46 and 4.41, respectively, were obtained. In order to assess the applicability of the optimized enantioselective chromatography conditions in real-life scenarios and on MS-based systems, a proof-of-concept application was efficiently carried out by analysing dry urine spot samples spiked with 1 by means of a LC-MS system. The (S)<(R) enantiomer elution order (EEO) was established for compounds 1 and 2 by analysing a pure enantiomeric standard of known configuration. This was not possible for 3 because not commercially available. For this compound, the same EEO was identified applying a procedure based on ab initio time-dependent density-functional theory simulations coupled to electronic circular dichroism analyses. Moreover, a molecular dynamics simulation unveiled the role of the phenolic OH in compound 3 in the retention mechanism

Applications of Structural Biology and Bioinformatics in the Investigation of Oxidative Stress-Related Processes

Reactive oxygen species (ROS)-mediated dysfunction of certain biological processes is implicated in different diseases in humans, including cardiovascular, cancer, or neurodegenerative disorders. Not only human cells and tissues are affected by ROS but also all other biological systems, including plants and microorganisms. Primary targets of ROS are proteins, lipids, and nucleic acids. Modifications of these macromolecules result mostly in the start of signalling cascades between proteins, proteins and DNA, DNA and RNA, proteins and RNA, proteins and lipids within single cell compartments, entire cells, or tissues. In this chapter, basics of tools of structural biology (i.e., X-ray crystallography, NMR, and EPR spectroscopy) as well as bioinformatics are presented. These tools are explained as well as how they can be applied in the analysis of ROS-mediated modifications within macromolecules and systems, and perspectives are discussed