Novel, efficient, facile, and comprehensive protocol for post-column amino acid analysis of icatibant acetate containing natural and unnatural amino acids using the QbD approach.

Qualitative and quantitative determination of amino acid composition using amino acid analysis (AAA) is an important quality attribute and considered an identity of therapeutic peptide drugs by the regulatory agencies. Although huge literature is available on pre- and post- column derivatization AAA methods, arriving at an appropriate hydrolysis protocol coupled with adequate separation of the derivatized/underivatized amino acids is always challenging. Towards achieving a facile and comprehensive protocol for AAA, the present work is geared towards developing a deeper understanding of the extent of hydrolysis of peptide, and the nature and stability of amino acids present in the peptide backbone. This defines the suitability of the method in meeting the end goals and the regulatory requirement. Analysis of historical data generated during the method optimization of AAA for icatibant acetate (ICT) using head space oven hydrolysis (HSOH) and microwave-assisted hydrolysis (MAH) methods helped in arriving at fast (< 1 h) and efficient hydrolysis (0.9-1.1 of theoretical residue) conditions. Better separations for the natural and unnatural amino acids were achieved using 3.45 ≤ pH ≤ 10.85, and a column oven gradient program. This approach was useful in meeting the method quality attributes [resolution (Rs) > 2.0; plate count (N) > 5600; and USP tailing factor < 1.2] with a target analytical method profile of relative amino acid mole ratios (RAAMR) in the range of 0.9-1.1 for Ser, Oic, Tic, Hyp, Ala (Thi), Gly and Pro, and between 2.7 and 3.3 for Arg. The developed method was validated as per the ICH guidelines and is precise, accurate, linear and robust.

Synthesis and antibacterial activity of novel 5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine-2-carbohydrazide derivatives.

BACKGROUND: The intensely increasing multi-drug resistant microbial infections have encouraged the search for new antimicrobial agents. Hydrazone derivatives are known to exhibit a wide variety of biological activities including anti-microbial. In heterocyclic moiety, imidazo[1,2-a]pyrimidines are the subject of immense interest for their antimicrobial activity and also for their analgesic, antipyretic and anti-inflammatory properties. RESULTS: Condensation of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine-2-carbohydrazide 7 with aromatic aldehydes a-k in ethanol at reflux led to the generation of hydrazone derivatives 8a-k in 80-92% yield. The synthesis of carbohydrazide 7 was accomplished in six steps from commercially available 2-amino pyrimidine. The structures of the synthesized compounds were confirmed by 1H, 13C NMR, Mass and IR spectral data. All the synthesized hydrazone derivatives 8a-k were tested in vitro for their antibacterial activity. Compounds 8d, 8e and 8f exhibited excellent antibacterial activity with zone of inhibition 30-33 mm against E. coli (Gram negative bacteria) and S. aureus (Gram positive bacteria). These compounds also exhibited excellent antibacterial activity with zone of inhibition 22-25 mm against P. aeruginosa (Gram negative bacteria) and S. pyogenes (Gram positive bacteria). CONCLUSION: Synthesized and recorded antibacterial activity of some new 5,6,7,8-tetrahydro-imidazo[1,2-a]pyrimidine-hydrazone derivatives.Graphical abstract:Synthesis of 5,6,7,8-tetrahydroimidazo[1,2-a]pyrimidine-2-carbohydrazide derivatives.

Synthesis and biological evaluation of benzimidazole-linked 1,2,3-triazole congeners as agents.

BACKGROUND: Benzimidazoles and triazoles are useful structures for research and development of new pharmaceutical molecules and have received much attention in the last decade because of their highly potent medicinal activities. FINDINGS: A simple and efficient synthesis of triazole was carried out by treatment of 2-(4-azidophenyl)-1H-benzo[d]imidazole (6) with different types of terminal alkynes in t-BuOH/H2O, sodium ascorbate, and Zn(OTf)2, screened for cytotoxicity assay and achieved good results. A series of new benzimidazole-linked 1,2,3-triazole (8a-i) congeners were synthesized through cyclization of terminal alkynes and azide. These synthesized congeners 8a-i were evaluated for their cytotoxicity against five human cancer cell lines. These benzimidazole-linked 1,2,3-triazole derivatives have shown promising activity with IC50 values ranging from 0.1 to 43 µM. Among them, the compounds (8a, 8b, 8c, and 8e) showed comparable cytotoxicity with adriamycin control drug. CONCLUSIONS: In conclusion, we have developed a simple, convenient, and an efficient convergent approach for the synthesis of benzimidazole-linked 1,2,3-triazole congeners as agents. Graphical Abstract Synthesis of 1,2,3-triazole derivatives.

Synthesis of 2-cyclopropyl-3-(5-aryl-1H-pyrazol-3-yl)-1,8-naphthyridine.

BACKGROUND: 1,8-Naphthyridine derivatives have attracted considerable attention because the 1,8-naphthyridine skeleton is present in many compounds that have been isolated from natural substances, with various biological activities. FINDINGS: N,N-dimethoxy-N-methyl-1,8-naphthyridine-3-carboxamide (1) on reaction with Grignard reagent forms 2-methoxy-1,8-naphthyridine-3-carbaldehyde (2). Compound 2 on reaction with different aromatic aldehydes provided 1-(2-cyclopropyl-1,8-naphthyridin-3-yl)-3-arylprop-2-en-1-ones (3a-e) and these compounds on cyclisation with hydrazine hydrate 99% yielded 2-cyclopropyl-3-(5-aryl-1H-pyrazol-3-yl)-1,8-naphthyridines (4-a-e). Synthesis of the target compounds involved the formation of 4a-e. It was accomplished using Grignard reaction, condensation reaction, and cyclisation reactions. All the synthesized compounds were readily soluble in DMSO. Spectral data of the synthesized compounds were in full agreement with the proposed structures. CONCLUSIONS: In conclusion, we have developed a simple and an efficient Synthesis of 2-cyclopropyl-3-(5-aryl-1H-pyrazol-3-yl)-1,8-naphthyridine.