1 research outputs found
The Effects of Quinoline and Non-Quinoline Inhibitors on the Kinetics of Lipid-Mediated β‑Hematin Crystallization
The throughput of a biomimetic lipid-mediated
assay used to investigate
the effects of inhibitors on the kinetics of β-hematin formation
has been optimized through the use of 24-well microplates. The rate
constant for β-hematin formation mediated by monopalmitoyl-<i>rac</i>-glycerol was reduced from 0.17 ± 0.04 min<sup>–1</sup> previously measured in Falcon tubes to 0.019 ± 0.002 min<sup>–1</sup> in the optimized assay. While this necessitated longer
incubation times, transferring aliquots from multiple 24-well plates
to a single 96-well plate for final absorbance measurements actually
improved the overall turnaround time per inhibitor. This assay has
been applied to investigate the effects of four clinically relevant
antimalarial drugs (chloroquine, amodiaquine, quinidine, and quinine)
as well as several short-chain 4-aminoquinoline derivatives and non-quinoline
(benzamide) compounds on the kinetics of β-hematin formation.
The adsorption strength of these inhibitors to crystalline β-hematin
(<i>K</i><sub>ads</sub>) was quantified using a theoretical
kinetic model that is based on the Avrami equation and the Langmuir
isotherm. Statistically significant linear correlations between lipid-mediated
β-hematin inhibitory activity and <i>K</i><sub>ads</sub> values for quinoline (<i>r</i><sup>2</sup> = 0.76, <i>P</i>-value = 0.0046) and non-quinoline compounds (<i>r</i><sup>2</sup> = 0.99, <i>P</i>-stat = 0.0006), as well as
between parasite inhibitory activity (D10) and <i>K</i><sub>ads</sub> values for quinoline antimalarial drugs and short-chain
chloroquine derivatives (<i>r</i><sup>2</sup> = 0.64, <i>P</i>-value = 0.0098), provide a strong indication that drug
action involves adsorption to the surface of β-hematin crystals.
Independent support in this regard is provided by experiments that
spectrophotometrically monitor the direct adsorption of antimalarial
drugs to preformed β-hematin