9 research outputs found
Effect of Long-Chain Fatty Acids on the Binding of Triflupromazine to Human Serum Albumin: A Spectrophotometric Study
Human serum albumin (HSA) in the blood binds long-chain fatty acids (LCFAs), and the number of bound LCFAs varies from 1 to 7 depending on the physical condition of the body. In this study, the influence of LCFA-HSA binding on drug-HSA binding was studied using triflupromazine (TFZ), a psychotropic phenothiazine drug, in a buffer (0.1 M NaCl, pH 7.40, 37°C) by a second-derivative spectrophotometric method which can suppress the residual background signal effects of HSA observed in the absorption spectra. The examined LCFAs were caprylic acid (CPA), lauric acid (LRA), oleic acid (OLA), and linoleic acid (LNA), respectively. Using the derivative intensity change of TFZ induced by the addition of HSA containing LCFA, the binding mode of TFZ was predicted to be a partition-like nonspecific binding. The binding constant (K M−1) showed an increase according to the LCFA content in HSA for LRA, OLA, and LNA up to an LCFA/HSA molar ratio of 3–4. However, at higher ratios the K value decreased, i.e. for OLA and LNA, at an LCFA/HSA ratio of 6–7, the K value decreased to 40% of the value for HSA alone. In contrast, CPA, having the shortest chain length (8 carbons) among the studied LCFAs, induced a 20% decrease in the K value regardless of its content in HSA. Since the pharmacological activity of a drug is closely related to the unbound drug concentration in the blood, the results of the present study are pharmaco-kinetically, pharmacologically, and clinically very important
Potentiometric Immunosensor Using Artificial Antibody Based on Molecularly Imprinted Polymers
Polydiacetylene Liposomal Aequorin Bioluminescent Device for Detection of Hydrophobic Compounds
In
this study, a polydiacetylene liposomal aequorin bioluminescent
device (PLABD) that functioned through control of the membrane transport
of Ca<sup>2+</sup> ions was developed for detecting hydrophobic compounds.
In the PLABD, aequorin was encapsulated in an internal water phase
and a calcium ionophore (CI) was contained in a hydrophobic region.
Membrane transport of Ca<sup>2+</sup> ions across the CI was suppressed
by polymerization between diacetylene molecules. On addition of an
analyte, the membrane transport of Ca<sup>2+</sup> ions across the
CI increased, and Ca<sup>2+</sup> ions from the external water phase
could diffuse into the internal water phase via the CI, which resulted
in bioluminescence of the aequorin. Lidocaine, procaine, and procainamide
were used as model compounds to test the validity of the detection
mechanism of the PLABD. When each analyte was added to a suspension
of the PLABD, bioluminescence from the aequorin in the PLABD was observed,
and the level of this bioluminescence increased with increasing analyte
concentration. There was a linear relationship between the logarithm
of the analyte concentration and the bioluminescence for all analytes
as follows: <i>R</i> = 0.89 from 10 nmol L<sup>–1</sup> to 10 mmol L<sup>–1</sup> for lidocaine, <i>R</i> = 0.66 from 10 nmol L<sup>–1</sup> to 100 μmol L<sup>–1</sup> for procaine, and <i>R</i> = 0.74 from
100 nmol L<sup>–1</sup> to 100 μmol L<sup>–1</sup> for procainamide. Compared to the traditional colorimetric method
using polydiacetylene liposome, the PLABD was superior for both the
sensitivity and dynamic range. Thus, PLABD is a valid, simple, and
sensitive signal generator for detection of hydrophobic compounds
that interact with PLABD membranes