Naturally occurring chemicals data sources

The early developments of CPT research are the subject of authoritative reviews by Wall and Wani [2,47-51], Hutchinson [3,52], and OberUes et al. [53], whereas newer research, including total synthesis and chemical modificatitHis is covered in reviews by Yang [54], Nessler [55], Hecht [56], Zu [57], Du [58], and Dallavalle et al. [59]. Clinical use of camptothecins is a subject of excellent reviews of Verweij [4], Simanek [60], Zunino [61], and a dedicated monograph [7], Valuable source of chemical data of naturally occurring camptothecins is Encyclopedia of Alkaloids [62],... 

Biomarkers of exposure are an indicator of absorbed dose and may present unique advantages in exposure assessment. Biomarkers demonstrate that internal exposure has occurred and can be used to estimate chemical uptake over time and help establish the relationship between exposure and effect. They are apical in nature, in that they account for and integrate over all sources of exposure. Specifically in relation to potentially sensitive subpopulations like children, biomarkers may be able to identify increased absorption or biological response in comparison with the general population. Biomarker data alone cannot be used to establish source and route of exposure and are limited in providing information on frequency, duration, and intensity. Moreover, metabolism of any chemical... 

The elucidation of catalytic mechanisms of enzymes by diffraction methods is very difficult, even when the three-dimensional structure has been determined to a reasonably high resolution. With conventional X-ray sources, diffraction data collection for macromolecules usually takes days, while chemical reactions that are catalyzed by enzymes may occur in fractions of a second. Nonetheless, it has been possible to study catalysis by altering the experimental conditions (e.g., pH, ionic strength, or temperature) such that substrate is much more slowly converted to product. Alternatively, the chemical nature of the substrate and/or... 

It is, at best, only possible to speculate on the routes of the coalification process on the basis of the current environment of the coal. Lack of substantiating data for the geological history of the sample as well as the lack of any data, other than speculative data, on the nature of the source material, make determination of the chemistry and physics of coalification extranely difficult if not impossible. Identifying the chemical reactions that occurred to form coal from the precursor material is somewhat more difficulty. 

According to CoE active principles" are chemically de ned substances, which occur in certain natural avoring source materials and preparations and which, on the basis of existing toxicological data, should not be used as avoring substances in their own right [9]. 

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