A Simple, Inexpensive Apparatus for Performance of Preparative Scale
Solution Phase Multiple Parallel Synthesis of Drug Analogs. I. Preparation
of a Retrospective Library of Quinolone Antiinfective Agents. Pp. 73-88.
K.E. Frank, M. Jung and L.A. Mitscher
[Abstract]
A Simple, Inexpensive Apparatus for Performance of Preparative Scale
Solution Phase Multiple Parallel Synthesis of Drug Analogs. II. Biological
Evaluation of a Retrospective Library of Quinolone Antiinfective Agents.
Pp. 89-100.
K.E. Frank, P.V. Devasthale, E.J. Gentry, V.T. Ravikumar, A. Keschavarz-Shokri,
L.A. Mitscher, A. Nilius, L.L. Shen, R. Shawar and W.R. Baker
[Abstract]
New Developments in Automated PrepLCMS Extends The Robustness and Utility
of the Method for Compound Library Analysis and Purification. Pp. 101-111.
L. Zeng, X. Wang, I. Wang and D.B. Kassel
[Abstract]
[Back to top] A Simple,
Inexpensive Apparatus for Performance of Preparative Scale Solution Phase
Multiple Parallel Synthesis of Drug Analogs. I. Preparation of a Retrospective
Library of Quinolone Antiinfective Agents. K.E. Frank, M. Jung and L.A.
Mitscher.
A simple inexpensive apparatus is described consisting of conveniently
commercially available components which is suitable for the solution phase
multiple parallel synthesis of 24-72 analogs of drug-like molecules. The
use of the apparatus is illustrated by preparation of a retrospective library
of over 100 analogs of antimicrobial fluoroquinolones prepared in 0% to
quantitative yields. Each analog was prepared in up to 150 mg quantity
and each was analyzed by NMR and mass spectrometric techniques to verify
its purity and identity.
[Back to top] A Simple,
Inexpensive Apparatus for Performance of Preparative Scale Solution Phase
Multiple Parallel Synthesis of Drug Analogs. II. Biological Evaluation
of a Retrospective Library of Quinolone Antiinfective Agents. K.E. Frank,
P.V. Devasthale, E.J. Gentry, V.T. Ravikumar, A. Keschavarz-Shokri, L.A.
Mitscher, A. Nilius, L.L. Shen, R. Shawar and W.R. Baker.
A series of pure fluoroquinolone antiifective agents was prepared by
multiple parallel synthesis using a simple new apparatus. These compounds
were evaluated biologically against Gram-positive and Gram-negative microorganisms
and against a BCG strain transfected with luciferase in a fluorescence-based
antitubercular assay. Activity against relatively fast growing, acid-fast
Mycobacterium smegmatis was determined in part by agar-dilution
streak assays. Data obtained against Escherichia coli-derived DNA
gyrase does not correlate well with whole cell assays against E. coli.
These compounds were assayed by a convenient glass-fiber filter binding
method modified for high throughput screening. In these analogs, the results
with a N-1 cyclopropyl substituent were often inferior to those obtained
with a N-1 2',4'-difluorophenyl substituent. None of the new compounds
prepared was superior in its antimycobacterial potency to ciprofloxacin
or temafloxacin.
[Back to top] New Developments
in Automated PrepLCMS Extends The Robustness and Utility of the Method
for Compound Library Analysis and Purification. L. Zeng, X. Wang, I. Wang
and D.B. Kassel.
New developments in the high throughput purification of combinatorial
libraries by automated preparative LC-MS is presented. To facilitate high
speed purifications at the multi-milligram level, short columns operated
at ultra high flow rates were incorporated. In order to match the linear
velocity of the short analytical columns for high speed separations (operated
at 4.0 mL/min), it was required to operate the preparative columns at flow
rates in excess of 70 mL/min. For chromatographically well - behaved compounds,
analytical LC-MS analyses and preparative LC-MS analyses could be achieved
in as little as 5 mm. For compounds exhibiting poor chromatographic peak
shapes and/or for compound mixtures requiring higher resolution separations,
slightly longer preparative LC-MS analysis times were required (8-10 mm/sample).
Fraction collection based on mass-triggering (as opposed to UV triggering)
is an exquisitely sensitive and selective technique for purifying combinatorial
libraries. However, because of its inherent selectivity (i.e., only
the predicted synthetic product is isolated), synthetic by-products or
other explainable reaction products are ignored during the purification
process. In some instances, especially if the structures of these synthetic
by-products is known (or can be elucidated readily), these compounds might
and should be isolated for biological testing, as well. PrepLCMS purifications
in our laboratory have been achieved using Applescripting as a way to permit
communication between the mass spectrometer and the fraction collector.
This Applescript was modified to permit the input of up to four unique
(+/or same) masses in the data acquisition software to permit purification
of up to four compounds from a single run. This was demonstrated for a
combinatorial library synthesized in a microtiter plate and purified directly
into a fraction collector containing four deep-well microtiter plates,
making these purified microtiter plates amenable to direct biological screening.