Beilstein Substructures Searching

Structure searching and display software are host-specific. The Softon Substructure Search System (S4) was developed by the Beilstein Institute and Softon of Graefelfing Germany (50). It is a full structure and substructure searching module. The S4 is used in-house by the Beilstein Institute and is operated by DIALOG. STN uses CAS ONLINE s messenger software for on-line structure searching of the Beilstein on-line database (51). 

CAS/STN International. CAS/STN offers structure searchable files such as Registry, Beilstein, MARPAT, CASREACT, and Gmelin a variety of learning files, eg, LRegistry, LBeilstein, LMARPAT, and LCASREACT and software products such as STN Express for on-line structure and substructure searching. Chemical Abstracts Service, a division of the American Chemical Society, has published Chemical Abstracts since 1907 and joindy operates STN International with FIZ Kadsruhe and the Japan Information Center of Science and Technology. 

In many ways, the field of chemistry is extremely fortunate in having had powerful, specialized searching tools like SciFinder Scholar, STN Express, and MDL Crossfire (for Beilstein and Gmelin) available for many years. These tools permit a high degree of flexibility in searching for example, one can find journal articles that refer to compounds containing particular substructures, search for physical properties of particular compounds, and so on. However, these are bounded tools ... 

The HTSS system has been previously used for substructure searches of the Beilstein database on the Orbit online system, but this service was withdrawn in 1992 and replaced by the Dialog online system [28], which allows one to perform substructure searches of the Beilstein database using another substructure search system called S4. 

The structures of the Beilstein compounds are stored in connection tables (CT s) to allow a very flexible structure and substructure search. Since most commercially available structure/substructure handling programs such as MACCS (MDL) or DARC (Telesystemes/Questel) work on the basis of CT s, the Beilstein Registry Connection Table (BRCT) can be easily adapted for in-house systems. 

The system has been designed for both an optimised vectorial coprocessing unit connected to a mainframe to free the main CPU from the very special burden of substructure search, and a stand alone microprocessor-based substructure search system for selected parts of the Beilstein structure file (Beilstein Selects). 

The SDF structure file is used for delivery to hosts and in-house customers of the Beilstein structure file. Other delivery formats produced by the registry software include Tel6systemes-DARC and MDL MOLfile formats. Large DARC and MOLfile structure files have been created at the Beilstein Institute for the purpose of benchmarking the DARC-SMS and MDL MACCS-II substructure search systems against the S4 substructure search system developed jointly by the Beilstein Institute and the software house Softron GmbH . 

Four chapters on other operational substructure search systems follow. Jean Marcah and co-workers describe the Du Pont global technical information system Steve Welford and Clemens Jochum report on chemical structure registration for Beilstein Online Peter Rusch also covers Beilstein Onhne in a paper about substructure searching on Dialog and the DARC Toolkit which was described by Pascal Huguet is summarised in a chapter written by Bill Town with some suggestions from myself and Pierre Buffet of Questel. 

We would stress that CrossFire is an excellent example of this sort of interactive involvement of the end user, with practically immediate response times, but is by no means the only system attempting to provide this. However, the example is particularly relevant because of the fact that the Beilstein file under traditional access at the online hosts STN and DIALOG displays no possibility of such fluent combination of document, substance, property, and reaction views, and substructure searching can be at least an order of magnitude slower. That this is not due to an inherent deficit of online files as opposed to inhouse files is shown by the fact that many subscribers to CrossFire do use this client/server system via remote access (i.e., by the telephone system, online). Rather, it is an indication of the flexibility, immediacy, and integration... 

In the case of the second problem, however, it is both possible and desirable to give a definition of the search tool, and that is the purpose of this paper. The LN is a flexible and useful tool, but contains the seeds of much difficulty if the concept is applied incautiously. It is not a type of substructure searching, nor is it a Markush search. To repeat the above objective once more, the intention behind the LN is to retrieve those sorts of structures which one might have found within a few pages of the given structure, had the user been looking in an Omnibus Edition of the Beilstein Handbook. 

A number of systems now offer graphics-based substructure search capabilities for online access to a variety of chemical structure data bases. From December 1988 the first subset of the Beilstein Online data bank (organic heterocyclic compounds reported in the literature prior to 1960) goes online on STN International. Other hosts, which at present offer only name-based structure and substructure search capabilities are also likely to provide online access to the Beilstein files in the near future these include Dialog, Pergamon Orbit Infoline and Datastar. 

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