Page 127 - Chiral Separation Techniques

104 4 CHIRBASE: Database Current Status and Derived Research Applications using …

For the inexperienced or infrequent users it is even more of a problem. Inexperi-
enced users should have the ability to exploit easily the wide variety of structural
search techniques.
To address these issues regarding adequate structural searching in CHIRBASE,
some facilities have been recently added to the user interface. The result is the auto-
matic generation and search of strategic 2D query structures defined with the help of
the following commands (Fig. 4-5):
Auto Search: This button initiates from a structure query two or three automated
series of search: exact and substructure searches in local desktop versions; exact,
substructure and similarity searches in network version (under ISIS/Host). All the
result lists are saved in CHIRBASE using « exact-auto », « SSS-auto » and
« SIMXX %-auto » names. XX is the highest similarity search value (from 80 %
to 40 %) allowing to retrieve hits in CHIRBASE. The records in all the lists
are unique. The SSS-auto list does not include records that are in the exact-auto
list. The SIMXX %-auto list does not include records that are in exact and SSS-
auto lists.
Auto Build: This application has been built upon the knowledge and experiences
of our working group in order that beginner has access to all pertinent informa-
tion. Auto Build automatically adds in the sample query structure the appropriate
atom and bond query features. Then clicking on SSS button initiates a substruc-
ture search. Some examples of the query features, which may be added to a query
structure, are:
– I, Cl, F, Br atoms are replaced by a list of halogens [I, Cl, Br, F].
– Cycles or chains are respectively specified with the “Rn” or “Ch” query bond
features.
– The query atom «A» (Any atoms) is added in phenyl, naphthyl, etc. aromatic
cycles to allow finding any hetero-aromatic cycles.
– S/D (Single/Double bonds) query bond features added if tautomers can be built
from sample structure.
When a search of any sort is completed, the number of hits is reported to the user.
The search can be further narrowed by restricting the range of structural features to
be retrieved. Specific substituents can be added and substring/numerical searches can
also be included on fields such as “alpha” and “CSP trade name”. Here, the rapidity
with which results to the queries are provided is decisive, because the answers often
constitute the support of a subsequent query. This feedback loop is extremely
resourceful and any use of chemical database should be based around this inventive
approach. A highly interactive system which supplies immediately the answer to a
question enables the user to detect the defaults in a question and then successively to
adjust the query until he or she finds the best questions which are often not well-
known in the beginning of the search. Thus, the crucial point in searching CHIR-
BASE is not only how to formulate a question, but also to find the best questions. That
is why different output forms have been developed to visualize the results of database
searches: either full data for each matching record, concise data comprising selected
fields (the summary form is displayed in Fig. 4-6) or tables are available.