High-Yielding Automated Convergent Synthesis of No-Carrier-Added [11C-Carbonyl]-Labeled Amino Acids Using the Strecker Reaction

Recent Review on the Extraction and Qualitative Assay of Cysteine and Other Amino Acids from Vellore Feather Waste and Molecular Docking Studies of Cysteine for Pharmacological Applications

Products produced from waste are a relatively recent innovation. Feather substrates are abundant in keratin content and improper disposal can cause ecosystem contamination. However, these pollutants can be transformed into value-added products for industrial application. Physical, chemical and cutting-edge microbiological methods were utilized for decomposing keratin and aid in the identification and estimation of amino acids from poultry feather wastes. These beneficial approaches are receiving more attention due to their retrieval of harmless and value added byproducts. These keratin-based compounds are used widely in pharmaceutical, livestock feed, fertilizer, and a variety of other industrial sectors. Since keratin is primarily consisting of amino acids, it can be utilized to affirm and estimate the amino acids in these feather substrates. This study primarily highlights the various methodologies employed for the qualitative estimation of amino acids in feather waste samples and the inhibitory activity of keratinase enzyme by EDTA and pepstatin in order to accumulate amino acids for drug delivery purpose and their importance in various pharmaceutical industries. In addition to that, molecular docking studies of cysteine with many standard pharmaceutical drugs like acetaminophen, pethidine, methylphenidate, carbamazepine, cillin and amlodipine were performed using autodock to demonstrate how cysteine greatly reduces conventional drug toxicity and its side effects.

Radiosynthesis, Preclinical, and Clinical Positron Emission Tomography Studies of Carbon-11 Labeled Endogenous and Natural Exogenous Compounds

The presence of positron emission tomography (PET) centers at most major hospitals worldwide, along with the improvement of PET scanner sensitivity and the introduction of total body PET systems, has increased the interest in the PET tracer development using the short-lived radionuclides carbon-11. In the last few decades, methodological improvements and fully automated modules have allowed the development of carbon-11 tracers for clinical use. Radiolabeling natural compounds with carbon-11 by substituting one of the backbone carbons with the radionuclide has provided important information on the biochemistry of the authentic compounds and increased the understanding of their in vivo behavior in healthy and diseased states. The number of endogenous and natural compounds essential for human life is staggering, ranging from simple alcohols to vitamins and peptides. This review collates all the carbon-11 radiolabeled endogenous and natural exogenous compounds synthesised to date, including essential information on their radiochemistry methodologies and preclinical and clinical studies in healthy subjects.

The Hantzsch reaction for nitrogen-13 PET: preparation of [13N]nifedipine and derivatives

Nitrogen-13 is an attractive but under-used PET radionuclide for labelling molecules of biological and pharmaceutical interest, complementing other PET radionuclides. Its short half-life (t1/2 = 9.97 min) imposes synthetic challenges, but we have expanded the hitherto limited pool of 13N labelling strategies and tracers by adapting the multicomponent Hantzsch condensation reaction to prepare a library of 13N-labelled 1,4-dihydropyridines from [13N]ammonia, including the widely-used drug nifedipine. This represents a key advance in 13N PET radiochemistry, and will serve to underpin the renewed interest in clinical opportunities offered by short-lived PET tracers.

Petasis vs. Strecker Amino Acid Synthesis: Convergence, Divergence and Opportunities in Organic Synthesis

α-Amino acids find widespread applications in various areas of life and physical sciences. Their syntheses are carried out by a multitude of protocols, of which Petasis and Strecker reactions have emerged as the most straightforward and most widely used. Both reactions are three-component reactions using the same starting materials, except the nucleophilic species. The differences and similarities between these two important reactions are highlighted in this review.

Radiosynthesis of [11C]LY2795050 for Preclinical and Clinical PET Imaging Using Cu(II)-Mediated Cyanation

Copper-mediated ¹¹C-cyanation reactions have enabled the synthesis of PET radiotracers from a range of readily available precursors and avoid the need to use more toxic Pd catalysts. In this work we adapt our recently developed ¹¹C-cyanation of arylpinacolboronate (BPin) esters for the cGMP synthesis of [¹¹C]LY2795050, a selective antagonist radiotracer for the kappa opioid receptor (KOR). [¹¹C]LY2795050 was synthesized in 6 ± 1% noncorrected radiochemical yield (based on [¹¹C]HCN, n = 3) using an automated synthesis module. Quality control testing confirmed the suitability of doses for preclinical and clinical PET imaging (radiochemical purity >99%; specific activity >900 mCi/μmol; residual Cu < 0.1 μg/mL). PET imaging was conducted in rodent and nonhuman primates, showing good brain uptake of [¹¹C]LY2795050 and the expected distribution of KOR. Analogous imaging with [¹¹C]carfentanil (a selective mu opioid receptor (MOR) radiotracer) revealed the anticipated regional differences in MOR and KOR distribution in the primate brain.