Page 141 - Chiral Separation Techniques

118 4 CHIRBASE: Database Current Status and Derived Research Applications using …

where D is the scaled value, L is the original luminance, and L and L are the
i i min max
minimum and maximum values of luminance.
As we have already indicated, the diversity value of molecule sets combining two
CSPs is difficult to interpret on an absolute scale. Only the relative position of each
set can be useful to compare, and also the arrangement of the points in regard to the
molecular diversity inherent to each individual molecule set of CSP.
On this basis, the AD-OD combined set appears to be the most diverse, and its
score establishes a practical larger bound. It is interesting to note that this combined
set has a larger diversity than each original AD and OD set. This increase of diver-
sity is also observed for the combined OD-Whelk set. This may explain why these
CSPs are often good candidates in CSP screening strategies. Comparison of Whelk-
Pirkle set reveals no reduction of diversity of the original Whelk set. This result sug-
gests that more specific Pirkle-like CSPs contribute well to augment the diversity
space defined by the Whelk-O 1 CSP.

Fig. 4-15. Plot of pairs of CSP according to a scaled value of map luminance.

More surprising is the loss of diversity shown by the AGP-OVM combined set;
this result seems to confirm the significant “overlap” of AGP and OVM solutes
found in earlier works [30].
As a first conclusion, this work shows that similarity coefficients, which code
molecules in terms of chemical substructures, are useful to assess the efficiency of
CSPs. The purpose of this work was not to propose a new method for solving the