DARC substructure search systems

Attias, R. "DARC Substructure Search System A New Approach to Chemical Information". J. Chem. Inf. Comput. Sci. 1983, 23,102-108. 

Attias R. DARC substructure search system a new approach to chemical information. J Chem Inf Comput Sci 1983 23 102-108. 

Description> Acquisition> Retrieval, and Correlation File. This is the only other public substructure search system, apart from CAS Online, that provides full access to the CAS Chemical Registry File. The DARC file, commercially available on-line from Telesystems-Questel, offered the first public on-line implementation of substructural searching of the CAS Chemical Registry System. The advantages and disadvantages of the CAS Online and DARC systems have been discussed (49). 

Hicks MG, Jochum C. Substructure search systems. 1. Performance comparison of the MACCS, DARC, HTSS, CAS Registry, MYSSS, and S4 substructure search systems. J Chem Inf Comput Sci 1990 30 191-199. 

Wliilst a substructure search system generally operates by finding all structures in the database which contain the specified query structure embedded within them, a number of different ways are used to specify the exact manner in which the query may be embedded. In some cases (e.g., DARC) this involves specifying as free sites those atoms which can have connections other than those shown in the query in other cases (e.g., STN International) it involves specifying the permissible number of connections for certain atoms. It may also be possible to specify whether or not a ring system can be embedded in a larger ring system, or have only acyclic substituents. 

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. 

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. 

Chemical data base systems, and especially the DARC Structure Management System (DARC-SMS), have from the beginning offered sophisticated capabilities for chemical structure registration and structure, or substructure, or generic substructure search. 

A more exhaustive search for cognate substructures can be carried out with the CAS Online System, where more than 600000 substances are searchable through Chemical Abstracts, in France the DARC system is used similarly. In this approach, some biological data will be delivered directly, but more can often be obtained by inserting the CAS number of the substance into the US National Institute of Health s MEDLARS system (available without charge in many countries through local Departments of Health). 

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