title: Effect of long-chain Fatty acids on the binding of triflupromazine to human serum albumin: a spectrophotometric study.
abstract: 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.
authors: Kyoto Pharmaceutical University, 5 Nakauchicho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors: Keisuke
authors: K
authors: Kitamura
authors: Kyoto Pharmaceutical University, 5 Nakauchicho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors: Shigehiko
authors: S
authors: Takegami
authors: Kyoto Pharmaceutical University, 5 Nakauchicho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors: Rumi
authors: R
authors: Tanaka
authors: Chemistry Department, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt. ; Chemistry Department, Faculty of Science, King Khalid University, Abha 9004, Saudi Arabia.
authors: Ahmed Ahmed
authors: AA
authors: Omran
authors: Kyoto Pharmaceutical University, 5 Nakauchicho, Misasagi, Yamashina-ku, Kyoto 607-8414, Japan.
authors: Tatsuya
authors: T
authors: Kitade
keywords: Drug Protein Binding; HSA; Long-Chain Fatty Acid; Second-Derivative Spectrophotometry; Triflupromazine