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A Brief Background
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
Reactions of organic molecules are, for the most part, governed by the presence of heteroatoms. They have the ability to disturb the electron density within the local area of the hydrocarbon skeleton and therefore create a reactive centre. The positioning and nature of the bonding of heteroatoms in organic molecules are identified as functional groups, which will undergo characteristic reactions.
Heterocyclic Drug Design and Development
Published in Rohit Dutt, Anil K. Sharma, Raj K. Keservani, Vandana Garg, Promising Drug Molecules of Natural Origin, 2020
Garima Verma, Mohammad Shaquiquzzaman, Mohammad Mumtaz Alam
Depending on the carbon framework, organic compounds can be classified into the open chain and closed chain or cyclic compounds. Cyclic compounds refer to those having atoms bound to each other in the form of a ring. These cyclic compounds can be sectioned into homocyclic and heterocyclic compounds (Figure 9.2). Homocyclic compounds, also known as carbocyclic or isocyclic compounds are the ones in which ring comprises of one type of atoms, mainly carbon. In heterocyclic compounds, the ring is formed by at least two different types of atoms (including a carbon). All atoms apart from carbon that are present in a ring are known as heteroatoms. However, in the majority of compounds, a major portion of the ring is composed of carbon. Most commonly witnessed heteroatoms include nitrogen, sulfur, and oxygen (Farlex. Heterocyclic Compounds. The Free Dictionary).
Radiotracer Interactions with Sex Steroid Hormone Receptor Proteins (Receptor Mapping)
Published in Lelio G. Colombetti, Principles of Radiopharmacology, 1979
Raymond E. Counsell, William H. Klausmeier
The following list summarizes the structure-activity relationships deduced from this discussion: The C19 methyl group and 4–5 double bond are unessential for high activity.The C3 carbonyl group is fairly important, but not essential for moderate activity.The 17β-alcohol and the proper stereochemical configuration at the other asymmetric centers are essential for significant androgenic activity.Introduction of unsaturation generally leads to retention or enhancement of activity.Substitution at the 1α, 7α, and 17α positions generally leads to retention or enhancement of activity.Substitution by nonbulky groups at the 2, 4, and 6 positions are generally well tolerated, while bulkier groups are not.Substitution at the 7β and 16 positions usually leads to a reduction in activity.Introduction of Group VI heteroatoms in the vicinity of the C3 position may enhance binding affinity.
Novel amides of mycophenolic acid and some heterocyclic derivatives as immunosuppressive agents
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Juliusz Maksymilian Walczak, Dorota Iwaszkiewicz-Grześ, Michalina Ziomkowska, Magdalena Śliwka-Kaszyńska, Mateusz Daśko, Piotr Trzonkowski, Grzegorz Cholewiński
MPA as a fully substituted aromatic compound possesses no protons in the aromatic region. This fact simplifies amides’ 1H NMR spectrum analyses since newly incorporated moieties contribute aromatic and amide protons solely. All spectra are determined by the deshielded amide proton and phenolic one as well as recently introduced aromatic species. Remaining signals represent MPA structure and are sometimes shifted due to magnetic environment modifications. Some lapping may occur as implemented amines bear functional groups or spacers appearing in the same 1H NMR regions as MPA structural units. 13C NMR spectra are also characterised by MPA core and added value in the shape of newly introduced carbon atoms. Some dissimilarities in the nucleus characteristics may occur (especially in the case of amide group carbon) as well as for amine-based units. The latter one is represented by deshielded C(2) heteroaromatic carbon and C(3a)/C(7a) positions. Remaining loci differ with heteroatom electronegativity and substituent character, sometimes precluding precise carbon atoms assignment. Some 1H and 13C NMR spectra show long and short distance spin decoupling brought by fluorine atoms, namely in A11 and A14 cases. More detailed information about the character of heteroaromatic interactions within 13C NMR spectroscopy may be found in the literature38,39.
An integrated in silico and in vivo approach to determine the effects of three commonly used surfactants sodium dodecyl sulphate, cetylpyridinium chloride and sodium laureth sulphate on growth rate and hematology in Cyprinus carpio L
Published in Toxicology Mechanisms and Methods, 2022
Ritwick Bhattacharya, Ismail Daoud, Arnab Chatterjee, Soumendranath Chatterjee, Nimai Chandra Saha
Before docking, the predicted protein files were loaded into Biovia Discovery studio for preparation steps. The steps the addition of polar hydrogen and removal of heteroatoms. Removal of water was not performed as the presence of water is essential to ensure a relay between the compound and the active site and thus create networks of hydrogen bonds (Klebe 2006). On the other hand, water molecules in the cavities of proteins can sometimes be a fundamental element as some algorithms can simulate the presence of water molecules in the cavities of proteins (Marechal 2007). Finally the minimzation of energy was performed using YASARA energy minimization server (Krieger et al. 2009) and the disputed amino acids were repaired using Molegro Virtual Docker software. The binding affinity of 3 surfactants with target protein was predicted using CB-Dock which is designed to perform docking at predicted sites, instead of the entire surface of a protein. It implements Autodoc Vina (1.12) for performing docking analysis (Liu et al. 2020). The docking pose of the ligand-protein complex was selected based on the lowest vina score and RMSD value of less than 2 Å (Liu et al. 2020). Finally, the bond type and interaction between active site residues of protein and ligand was obtained by using Protein-Ligand Interaction Profiler (PLIP) which aids in easy and fast identification of intermolecular interactions between biological macromolecules and their ligands (Salentin 2015; Adasme et al. 2021).
Role of human flavin-containing monooxygenase (FMO) 5 in the metabolism of nabumetone: Baeyer–Villiger oxidation in the activation of the intermediate metabolite, 3-hydroxy nabumetone, to the active metabolite, 6-methoxy-2-naphthylacetic acid in vitro
Published in Xenobiotica, 2021
Kaori Matsumoto, Tetsuya Hasegawa, Kosuke Ohara, Tomoyo Kamei, Junichi Koyanagi, Masayuki Akimoto
Typical FMO-catalyzed reactions have long been recognised as the monooxygenation of heteroatoms, including nitrogen, sulfur, and phosphorus (Ohmi et al.2003, Cashman 2008). However, recent studies have shown that FMO5 specifically catalyzed the Bayer-Villiger oxidation (BVO) of piperidine-4-one containing compounds such as E7016 (Lai et al.2011) and MRX-I (Meng et al.2015). NAB was recently demonstrated to be efficiently oxidised in vitro by the recombinant human flavin-containing monooxygenase (hFMO) 5 system to the corresponding acetate ester with high selectivity (Fiorentini et al.2017, Matsumoto et al.2020). A likely explanation is the subsequent biotransformation steps of the esters to 6-MNA. We also demonstrated using human S9 fractions that non-CYP enzymes are capable of forming the corresponding carboxylic acid, 6-MNA, from the acetate ester (Matsumoto etal.2020). However, the enzymes responsible for the conversion of 3-OH-NAB to 6-MNA currently remain unclear.