The properties of perphenazine (PPZ) and trifluoperazine (TFP) as fluorescent dyes were exploited to calculate their critical micellar concentrations. The relative fluorescence quantum yield of the two amphiphiles was dependent on their concentration, abruptly decreasing above 30-40 muM PPZ and 20-30 muM TFP. Evidence is presented that this phenomenon is driven by the formation of nonfluorescent drug aggregates. The type of inhibition kinetics displayed by PPZ and TFP on human erythrocyte acetylcholinesterase (AChE) was also dependent on drug concentration, turning from noncompetitive to a "mixed" inhibition type at concentrations at which PPZ and TFP were demonstrated to undergo micelle formation. Results support the notion that phenothiazines may interact with AChE both as monomers and micellar aggregates, producing different inhibitory effects.
Phenothiazines inhibit acetylcholinesterase by concentration-dependent-type kinetics. A study with trifluoperazine and perphenazine / Spinedi, A; Pacini, L; Limatola, Cristina; Luly, P; Farias, Rn. - In: BIOCHEMICAL PHARMACOLOGY. - ISSN 0006-2952. - STAMPA. - 44:(1992), pp. 1511-1514. [10.1016/0006-2952(92)90465-U]
Phenothiazines inhibit acetylcholinesterase by concentration-dependent-type kinetics. A study with trifluoperazine and perphenazine
LIMATOLA, Cristina;
1992
Abstract
The properties of perphenazine (PPZ) and trifluoperazine (TFP) as fluorescent dyes were exploited to calculate their critical micellar concentrations. The relative fluorescence quantum yield of the two amphiphiles was dependent on their concentration, abruptly decreasing above 30-40 muM PPZ and 20-30 muM TFP. Evidence is presented that this phenomenon is driven by the formation of nonfluorescent drug aggregates. The type of inhibition kinetics displayed by PPZ and TFP on human erythrocyte acetylcholinesterase (AChE) was also dependent on drug concentration, turning from noncompetitive to a "mixed" inhibition type at concentrations at which PPZ and TFP were demonstrated to undergo micelle formation. Results support the notion that phenothiazines may interact with AChE both as monomers and micellar aggregates, producing different inhibitory effects.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
