Characterization of major degradation products of an adenosine A2A receptor antagonist under stressed conditions by LC-MS and FT tandem MS analysis

Intramolecular interactions and the neutral loss of ammonia from collisionally activated, protonated ω-aminoalkyl-3-hydroxyfurazans

Gas phase fragmentation reactions of monoprotonated 4-(3-aminopropyl)- and 4-(4-aminobutyl)-3-hydroxyfurazan were investigated to examine potential interactions between functional groups. The two heterocyclic alkyl amines were ionized by electrospray ionization (ESI, positive mode) and fragmented using tandem mass spectrometry (MS/MS). The fragmentation pathways were characterized using pseudo MS3 experiments, precursor-ion scans, and density functional computations. For both heterocyclic ions, loss of ammonia was the only fragmentation process observed at low collision energies. Computational analysis indicated that the most feasible mechanism was intramolecular nucleophilic displacement of ammonia from the protonated ω-aminoalkyl side chain by N5 of the furazan ring. The alkylated nitrogen in the resulting bicyclic product ion facilitated N-O bond cleavage; subsequent neutral losses of nitric oxide (NO) and carbon monoxide (CO) occurred by homolytic bond cleavages. Next in the multistep sequence, neutral loss of ethylene from a radical cation was observed. A less favorable, competing fragmentation pathway of protonated 4-(3-aminopropyl)-3-hydroxyfurazan was consistent with cleavage of the 3-hydroxyfurazan ring and losses of NO and CO. Overall, the similar fragmentation behavior found for protonated 4-(3-aminopropyl)- and 4-(4-aminobutyl)-3-hydroxyfurazan differed from that previously characterized for furazan analogs with shorter alkyl chains. These observations demonstrate that a small change in the structure of multifunctional, heterocyclic alkyl amines may significantly influence interactions between distinct functional groups and the nature of the fragmentation process.

Identification of a novel GLUT1 inhibitor with in vitro and in vivo anti-tumor activity

Glucose transporter (GLUT) is a group of membrane proteins which transport extracellular glucoses into cytoplasm, amongst GLUT1 is widely up-regulated in tumor cells. However, no FDA approved GLUT drug has been developed. In this study, we synthesized and identified a novel GLUT1 inhibitor (SMI277) based on in vitro assays and in vivo experiments. Compared with a known GLUT1 inhibitor, SMI277 showed stronger inhibitory activity to glucose uptake, and the inhibition was increased by 40 %. Lactate secretions were decreased by SMI277 in a dose dependent manner. SMI277 was able to inhibit cell proliferations and induce apoptosis of tumor cells. Compared to that of the control group, the tumor growth in mouse model with the administration of 10 mg/kg SMI277 was significantly alleviated and the tumor size was reduced by 58 % on day 21 after inoculation. Interestingly, SMI277 could negatively regulate the expression of GLUT1 protein. Ex vivo experiments showed that SMI277 was capable to enhance CD8⁺ T cell response. Residues Q283, F379 and E380 were identified as contact residues for GLUT1/SMI277 interactions by mutagenesis based binding affinity measurement. In conclusion, SMI277 appeared to be a good lead compound for drug development with specific GLUT1⁺ cancer treatment.

Identification and structural characterization of the stress degradation products of omeprazole using Q-TOF-LC-ESI-MS/MS and NMR experiments: evaluation of the toxicity of the degradation products

Omeprazole (OMP), a prototype proton pump inhibitor used for the treatment of peptic ulcers and gastroesophageal reflux disease (GERD), was subjected to forced degradation studies as per ICH guidelines Q1A (R2).

Characterization of impurities of HIV NNRTI Doravirine by UHPLC-high resolution MS and tandem MS analysis

World Health Organization estimates that 34 million individuals globally are living with Human Immunodeficiency Virus (HIV). Doravirine is a non-nucleoside reverse transcriptase inhibitors (NNRTI) being evaluated by Merck for the treatment of HIV-1 infection. Drug regulation authorities require the purity of a pharmaceutical to be fully defined. This is important to ensure that the pharmacological and toxicological effects are truly those of the drug substances and not because of the impurities. Thus, understanding the drug impurity profiles is critical to the safety and potency assessment of the drug candidate for clinical trials. The impurity characterization can also provide useful information for critical assessment of pharmaceutical processes. Advances in mass spectrometry instrumentation and methods allow the identification of impurities in pharmaceuticals with a minimum of sample material and increased sensitivity. In this study, a rapid and sensitive method was developed for the structural determination of the major impurities of doravirine. The study utilizes ultra performance liquid chromatography-high-resolution-tandem mass spectrometry (UHPLC-HRMS/MS) techniques to perform structure elucidation of the unknown structures. This approach has significant impact on impurity structural elucidation, and a total of five trace-level impurities of doravirine were characterized using the developed method. Copyright © 2016 John Wiley & Sons, Ltd.

LC-MS characterization of valsartan degradation products and comparison with LC-PDA

abstract Valsartan was submitted to forced degradation under acid hydrolysis condition as prescribed by the ICH. Degraded sample aliquots were separated via HPLC using a Hypersil ODS (C18) column (250 x 4.6 mm i.d., 5 µm). Either photodiode array (PDA) detection or mass spectrometry (MS) full scan monitoring of HPLC runs were used. HPLC-PDA failed to indicate Valsartan degradation under forced acid degradation, showing an insignificant peak area variation and that Valsartan apparently remained pure. HPLC-MS using electrospray ionization (ESI) and total ionic current (TIC) monitoring did not reveal any peak variation either, but inspection of the ESI mass spectra showed the appearance of m/z 306 and m/z 352 ions for the same retention time as that of Valsartan (m/z 436). These ions were identified as being protonated molecules of two co-eluting degradation products formed by hydrolysis. These assignments were confirmed by ESI-MS/MS with direct infusion of the degraded samples. The results showed that the use of selective HPLC-MS is essential for monitoring Valsartan degradation. Efficient HPLC separation coupled to selective and structural diagnostic MS monitoring seems therefore mandatory for comprehensive drug degradation studies, particularly for new drugs and formulations, and for method development.