Bioactive chemical structures

From a chemical point of view, the half-life of fluorine-18 allows multi-step synthetic approaches that can be extended over hours. Fluorine-18 has therefore, in spite of its somewhat limited chemical repertoire, been effectively used for the labelling of numerous both relatively simple and complex bioactive chemical structures [3,5-9], including high-molecular-weight macromolecules such as peptides, proteins [10-13] and oligonucleotides [14-18]. General considerations on radiochemistry involving short-lived positron emitters will be discussed in Section 2.3. 

Behavioral and psychological symptoms of dementia (BPSD), 72 Benzodiazepine receptors, 76-77 Benzylamines, fluorine substituted, 666-668 Bioactive chemical structures, 6 Bioceramics... 

B and W J Howe 1991. Computer Design of Bioactive Molecules - A Method for Receptor-Based Novo Ligand Design. Proteins Structure, Function and Genetics 11 314-328. i H L 1965. The Generation of a Unique Machine Description for Chemical Structures - A hnique Developed at Chemical Abstracts Service. Journal of Chemical Documentation 5 107-113. J 1995. Computer-aided Estimation of Symthetic Accessibility. PhD thesis. University of Leeds, itan R, N Bauman, J S Dixon and R Venkataraghavan 1987. Topological Torsion A New )lecular Descriptor for SAR Applications. Comparison with Other Descriptors. Journal of emical Information and Computer Science 27 82-85. 

Fig. 20 Chemical structure of Bfx and Fx derivatives with bioactivities depicted in Table 6...

Spore germination and protonemal growth and morphogenesis are therefore, useful systems to test in vitro, with good reproducibility, potential allelochemicals both through direct co-existence test in vitro or using the described bioassays to monitor/guide isolation, purification, characterization of chemical structure of bioactive compounds. 

The first clue regarding molecules ability to undergo bioactivation, the precursor to MBI, is often determined from its chemical structure. For example, certain substructures are prone to forming reactive intermediates capable of alkylating protein nucleophiles including CYP, as in the case of M BI. A comprehensive look at different chemical structures prone to CYP bioactivation has been reviewed recently [172,173],... 

The mechanistic basis of the anti-neoplastic activity of UDCA and the explanation for the significant difference in bioactivity of UDCA compared with DCA despite marked similarity in chemical structure remain unresolved. UDCA administration in healthy volunteers and colorectal adenoma patients has been demonstrated to decrease the proportion of DCA in aqueous phase stool. Therefore, one possible mechanism of the chemopreventative activity of UDCA is reduction of mucosal secondary bile acid exposure. Consistent with this idea, UDCA administration has been demonstrated to reduce the incidence of K-ras mutations and decrease Cox-2 expression in AOM-induced tumors, which is the opposite of the reported effects of DCA in the same model. However, it is clear that exogenous administration of UDCA has direct anti-neoplastic activity on human CRC cells in vitro, either alone or in combination with DCA, including anti-proliferative and anti-apoptotic effects, as well as induction of cell senescence. " ... 

John Siddall had intense scientific interest in two areas covered in this book. The chemical structures of the new bioactive substances discussed in the first section reveal configurations in which biological activity and specificity are highly dependent on isomeric differentiation, an area of synthesis that he understood and avidly pursued. He also advocated more extensive use of... 

Hert, J., Willett, P., Wilton, D.J., Acklin, P Azzaoui, K., Jacoby, E. and Schuffenhauer, A. (2004) Comparison of fingerprint-based methods for virtual screening using multiple bioactive reference structures. Journal of Chemical Information and Computer Sciences, 44 (3), 1177—1185. 

Bioactivation is a classic toxicity mechanism where the functional group or the chemical structure of the drug molecule is altered by enzymatic reactions. For example, the enzymatic breakdown of the analgesic acetaminophen (paracetamol), where the aromatic nature and the hydroxyl functionality in paracetamol are lost, yields A -acetyl-p-benzoquinone imine, a hepatotoxic agent. Paracetamol can cause liver damage and even liver failure, especially when combined with alcohol. 

Uemura, D. (2006). Bioorganic studies on marine natural products—Diverse chemical structures and bioactivities. Chem. Rec. 6, 235-248. 

The QSAR data show that glucuronidation can be either a detoxification or bioactivation mechanism, depending chemical structure. For N SAIDs, it appears to be mostly a detoxification mechanism. Nonetheless, the toxicity of acyl glucuronide and glucoside adducts (espedally as it relates to isomerization and protein adduct formation) must be considered when designing carboxylic acids [38]... 

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