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Radiometry
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Organic scintillators usually contain aromatic carbon compounds, consisting of carbon and hydrogen. In these compounds, the carbon atoms form benzene rings, each containing six carbon atoms and a carbon atom in the ring is thus bound to two carbon atoms and one hydrogen atom. This molecule is planar, that is, the orbitals of the bound electrons all lie in the same plane with a bond angle of 120°. However, one of the electrons in the carbon L-shell does not take part in the bonds, and these six electrons form orbitals that are orthogonal to the molecular plane. These π-electrons make it possible for the benzene molecule to bind to another benzene molecule. Absorption of energy may cause excitation of a π-electron, followed by emission of light upon de-excitation.
Sedative and Hypnotic Drugs
Published in Sahab Uddin, Rashid Mamunur, Advances in Neuropharmacology, 2020
Arup Kumar Misra, Pramod Kumar Sharma
For decades, it is a known fact that the name benzodiazepines (Fig. 11.1) have been synonymous with anxiolytic in addition to other properties like muscle relaxant, anticonvulsant, and sleep-inducing activity. These activities are due to the seven-membered heterocyclic ring structure comprising the benzene ring (Kovacic et al., 2013). The biological activity of benzodiazepines is increased by addition or substitution of chemical groups in different positions like methyl group but its substitution with larger groups decreases its potency. It is found that substitution of halogen or nitro group in the seventh position of 1,4-benzodiazepines will produce the sedative–hypnotic activity (Gerecke, 1983).
Contrast enhancement agents and radiopharmaceuticals
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
Ionic contrast agents, which are high in osmolality, had three atoms of iodine with two active particles (3:2), whereas the modern tri-iodinated low-osmolar contrast agents have three atoms of iodine with one active particle. An alternative to the single benzene ring molecule is the mono-acid dimer, where two tri-iodinated benzoic rings are linked together and the COOH of one ring is converted into an amide. This gives six iodine atoms and two active particles in each molecule (Fig. 2.4).
Discovery of novel benzohydroxamate-based histone deacetylase 6 (HDAC6) inhibitors with the ability to potentiate anti-PD-L1 immunotherapy in melanoma
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2023
Xiaopeng Peng, Ziwen Yu, Goverdhan Surineni, Bulian Deng, Meizhu Zhang, Chuan Li, Zhiqiang Sun, Wanyi Pan, Yao Liu, Shenglan Liu, Bin Yu, Jianjun Chen
The HDAC-inhibitory activities of the newly synthesised compounds were evaluated against Hela cell nuclear extracts (containing different HDAC isozymes) with tubastatin A as a reference compound22. As shown in Table 1, most compounds were endowed with potent HDAC-inhibitory activities (>50%) at 1 μM. Compound 10a, with no substituents at position 5 of C-ring, displayed relatively poor HDAC inhibitory activity (44.70% at 1 μM). Therefore, the activity of compounds with bulky and rigid benzene-ring substituents at position 5 of C-ring was evaluated. It was observed that, compared to the compounds with ortho-substituent in the phenyl E-ring (10k, 39.80% at 1 μM), compounds with para or meta-substituents in the E-ring exhibited relatively higher HDAC inhibitory activity (10b–j, 59.36–83.06% at 1 μM). Particularly, compound 10c demonstrated comparable HDAC inhibitory activity to the reference compound tubastatin A at 1 μM (83.06% vs. 86.33%) and slightly lower HDAC inhibitory activity than MS-275 (93.51%) or PCI-34051 (97.02%). Further, compounds with heterocyclic substitutions at position 5 also showed modest to good HDAC inhibitory activity (61.21–79.18% at 1 μM). These results suggest that a quinoline-based CAP group is optimal for HDAC-inhibitory activity.
Design, synthesis, and biological evaluation of arylmethylpiperidines as Kv1.5 potassium channel inhibitors
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Lingyue Zhao, Qian Yang, Yiqun Tang, Qidong You, Xiaoke Guo
By comparing the biological results of compounds DDO-02001 and DDO-02002, it can be seen that replacing the benzene ring of molecule DDO-02001 with a benzoxazole ring improved the biological activity (DDO-02001 IC50 = 17.7 μM vs. DDO-02002 IC50 = 8.96 μM). Carbonyl is not so important, because the removal of carbonyl lead to the promotion of inhibition effect proved by DDO-02002 and DDO-02003 (IC50 = 1.57 μM). Replacing the linker L from –NH– to –NH–CH2– slightly increased the activity (DDO-02003 vs. DDO-02005); Extending the carbon chain to –NH–CH2–CH2–, the activity decreased (DDO-02004 vs DDO-02009), suggesting the linker –NH–CH2– was the best choice. Different substituents on the benzene ring were changed to discuss their influence on the effect of the compound. Compared with DDO-02005, DDO-02006 with electron withdrawing group on the benzene ring has a decreased inhibition rate of Kv1.5 channel (IC50 = 3.24 μM), implying that methoxyl group might be a preferred option to improve the inhibitory activity. Changing the position and type of the electron donating group in DDO-02005 to get DDO-02007 and DDO-02008, the activity decreased, suggesting that para-methoxy substitution is the best choice to exert inhibitory activity.
A review on synthetic chalcone derivatives as tubulin polymerisation inhibitors
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Wenjing Liu, Min He, Yongjun Li, Zhiyun Peng, Guangcheng Wang
A class of novel chalcone derivatives 73 (Figure 49) were considered as potential antitumor agents by Huang et al.145. These newly synthesised chalcones showed good anticancer activity, which the IC50 values are mainly at the micromolar level. Thereinto, derivative 73a showed the most effective activity against tested tumour cell lines, including multidrug-resistant human cancer lines (IC50 of 3.75–8.42 µM). SAR analysis indicated that the introduction of EWG in the para-position of the lateral benzene ring may beneficial to the activity of the selected cancer cell lines. While the 4-position of the lateral benzene ring is modified with a halogen or hydroxyl group to render them ineffective. Additionally, the mechanism results showed that 73a induced apoptosis of NCI-H460 cells through the mitochondrial pathway, which also could effectively induce cell cycle arrest in the G2/M phase. Besides, the novel analogs could inhibit tubulin polymerisation through the tubulin polymerisation assay, and docking studies revealed that 73a could bind to the colchicine site of tubulin.