Compound availability databases

OtherD t b ses. Available from different vendors (Table 8). For example, the researcher can obtain physical properties by usiag the Merck Index Online or the Dictionary of Organic Compounds available by Chapman and Hall Chemical Database. In DIALOG, numeric databases are collected under the name of CHEMPROP. 

CS4JSI/SND. The Canadian Scientific Numeric Database Service (CAN/ SND) is provided by the Canada Institute for Scientific and Technical Information (ClSTl), a division of the National Research Council of Canada. It contains 140,000 ir spectra of 96,000 compounds. Entries consist of peak locations and some intensities. This system is searchable on-line using the SPIR (Search Program for Infrared Spectra) (85). Table 9 summarizes the available databases in the area of spectra. 

The need for an overall and combined chemical structure and data search system became clear to us some time ago, and resulted in the decision to build CHIRBASE, a molecular-oriented factual database. The concept utilized in this database approach is related to the importance of molecular interactions in chiral recognition mechanisms. Solely a chemical information system permits the recognition of the molecular key fingerprints given by the new compound among thousands of fingerprints of known compounds available in a database. 

Chemindex plus. This database contains 8000 pharmaceutical ingredients linked to 300,000 preparations. Chemindex plus [66] can be interrogated at the national or international level. It covers compounds available in 55 countries recording their brand name, local manufacturer, launch date, therapeutic class, and base forms. This product is commercially available from IMS HEALTH Global Services. 

Identification of commercially available compounds - assemble database ... 

The iResearch Library is ChemNavigator s compilation of commercially accessible screening compounds. The database tracks over 21.7 million samples from around 150 vendors based on 14 miUion unique structures, including both physically available and virtual compounds. 

The ACS also offers the "Beilstein Online Database." This is claimed to he the most complete and systematic collection or evaluated data oh organic compounds. The database is reviewed in a len-chapler. "The Beilstein Online Database Implementation. Content, and Retrieval." available from American Chemical Society. Washington. DO... 

MDL Information Systems, Inc., a subsidiary of Elsevier Science, Inc., also have a free Internet access to its database of commercially available substances, claimed to contain information on more than 400,000 chemicals (available from www.mdh.com No toxicity or environmental property data are given. Similarly, the ChemBridge Corp. provides a list of over available 450,000 substances to subscribers (www.chembridge.com). Russia s ChemStar Ltd. provides a similar type of database with over 500,000 compounds available (www.chemstar.ru). The list of compounds is downloadable in structure data hie (SDF) format and is being updated regularly. 

The 3-point and 4-point pharmacophore methods can be used to analyse and compare different sets of compounds and databases. Figure 7 illustrates the 4-point pharmacophores for the MDDR database [25], the Available Chemical Directory (ACD) [25], a company registry database and a set of combinatorial libraries reported by Mason and co-workers [7, 11, 13]. Previous studies [3] had shown the increase in resolution possible using 4-point instead of 3-point pharmacophores. 

Databases with assessed thermodynamic data for hundreds of substances are available, including alloys, semiconductors, geochemical compounds (silicates and other main-group oxides), aqueous solutions, and molten salts. The bulk of the commercially available databases are on metallurgical systems since the CALPHAD method finds ready applicability in the fields of metals processing and alloy development. 

From the total of 2.67 million compounds available from die 23 suppliers, 1.62 million unique structures were identified, of which just over 607,000 (37%) pass all the applied filters for drug-likeness. The databases for all 23 suppliers would need to be analysed to gain access to all 607,000 structures. The question thus arises could that operation be made more manageable if only a subset of suppliers were to be considered in other words, how few suppliers would be able to provide, between themselves, a workable proportion, say 90%, of those unique compounds The graph in Figure 7 shows that, by using approximately half of the suppliers, 90% of the unique, drug-like compounds would be accessible. 

Solubility is extremely difficult to calculate. Dozens of methods exist, but none is reliable enough to be used in the entire chemical diversity space populated by infinite drug candidates. Experimental solubility errors are relatively high and frequent. Moreover, solubility can change dramatically with the purity of the compounds, stability, and time. Solubility of liquid substances differs from that of solid phase compounds. Solubility is thermodynamically affected by crystal packing, influencing the process of crystal lattice disruption and hence polymorphism, amorphous solid compounds lead to imprecise experimental measures. Finally, publically available databases of solubility values contain a lot of errors. 

---