DARC system, development

Several groups have a special interest in chemical information handling, in particular the subjects of chemical structure storage and computer-assisted chemical synthesis. The most remarkable French contribution in this area is the DARC system developed by Jacques-fimile Dubois for molecular encoding and chemical information retrieval. ... 

Computer-aided structure elucidation (CASE) has been developed over a period of 30 years. Several major projects that were initiated and carried out during this time consist, in the main, of interdisciplinary efforts toward the automatic solution of problems arising from the everyday practice of chemists. The DARC system of Dubois et the Heuristic DENDRAL project developed at Stanford University, and the CHEMICS system of Sasaki et as well as the developments of... 

A number of commercial systems that were available at the time were evaluated. Several failed to meet all criteria, due to a lack of U.S. installations and/or U.S.-based system support groups. Those that failed were DARC/Questel, Telesystemes, Paris, France the NIH-EPA Chemical Information System CHEMPIX, developed by Moreaux of Roussel-Uclaf and marketed by Chemical Information Management Inc. and SYNLIB, marketed by Smith Kline Beckman. The Upjohn COUSIN system, developed by Dr J Howe, was not commercially available. Chemical Abstracts Service (CAS) private file support was considered too expensive. Security with the CAS file was also a concern of MSDRL since it could not be brought in-house. 

Whatever the search software offered, however, the database was of utmost importance. The DARC system not only offered a means to search generic structures in the short term, it also offered a way to record all of the information about structures found in patents, through a new and flexible input system. This capability was of incredible import to Derwent we could build a database that would not only serve the users today, but in future could be of more utility as search software was further developed. As opposed to the fragmentation code, there should never be a question of time-ranging. Moreover, though we assume that Markush DARC is a system not only of today but of tomorrow, we are building a database that can be converted and adapted to other search systems that may be offered by other organisations. 

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 . 

Dubois et al. developed the Description, Acquisition, Retrieval, Computer-aided design-Elucidation by Progressive Intersection of Ordered Structures (DARC-EPIOS) system for structural elucidation.Their approach was based on C spectra. These were predicted using an additive method, but based on their DARC descriptor of environment, as opposed to the more common HOSE code. The EPIOS system was designed to take account of the diagnostic (or not) nature of the C spectrum with respect to environment, i.e., depending on the specific sub-structures. 

To improve the interfacing of DARC with external systems a set of programs has been planned for development by a team of Telesystemes and Akzo staff. A new open-ended communication protocol has been written initialising a subprocess controlled by transferred logical names. Via this protocol the following options are achieved ... 

Based on ORACLE and DARC a number of research information systems are being built in our company. Both programs have already been proven to be stable for many years. ORACLE will be used for all alphanumerical data of compounds and DARC for the related structures. T 16syst%mes has developed, in co-operation with Organon,... 

By 1986, when we were ready to buy chemical structure software, there was a number of systems on offer. A year earlier the position might have been very different. The main contenders were MACCS, DARC and OSAC, a program derived from the reaction storage and searching program, ORAC. In addition, HTSS and SABRE were of interest although we had doubts about their state of development at the time. 

The major commercially available reaction indexing programs are REACCS (Molecular Design Limited), SYNLIB (started by Clark Still, developed by Smith, Kline and French and now sold by Dan Chodosh), ORAC (developed at the University of Leeds) and DARC-RMS (Telelsystemes). Pfizer s in-house system CONTRAST is noteworthy but is not available outside Pfizer. The release of CASREACT by Chemical Abstracts is awaited with interest. 

Markush DARC (MDARC) is commercially available on the Questel online system, and contains two databases World Patents Index Markush (WPIM), produced by Derwent Information, Ltd. and Markush Pharmsearch (MPHARM), produced by Institut National de la Ptopriete Industrielle (INPI, the French patent office). The initial development of MDARC was a collaboration between Questel and INPI. This development was later Joined by Derwent with commercial implementation in 1987. 

Schmuff has published a comparison of MARPAT and Markush DARC software. To generalize, at this stage both commercially available systems have similar capabilities in terms of retrieval and overall functionality. Both systems have the ability to represent in their databases and queries generic nodes typical of Markush structures in patents. Both systems have translation capabilities between generic node.s and specific nodes in database records and queries, and both systems have the ability to highlight elements in the database record that caused the retrieval. The similarities no doubt reflects the Sheffield connection, which both Questel and STN supported, but also the demands the patent searching community, which the developers of both systems consulted with extensively. 

The chemical system and the DBMS or the text retrieval system had to communicate together. To solve this problem Telesystemes has developed the DARC Communication Modules. The first version was released in 1986 and the software has been continuously improved from that date. 

Development Criteria. The development of the DARC Communication Modules took into consideration criteria which were considered as essential to build a chemical information system which meets the requirements of the researchers, while being easy to set up and to maintain. 

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