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Antitrypanosomal, Antileishmanial, And Antimalarial Activities Of Quaternary Arylalkylammonium 2-Amino-4-Chlorophenyl Phenyl Sulfides, A New Class Of Trypanothione Reductase Inhibitor, And Of N-Acyl Derivatives Of 2-Amino-4-Chlorophenyl Phenyl Sulfide, Seheli Parveen, M. O. Faruk Khan, Susan E. Austin, Simon L. Croft, Vanessa Yardley, Peter Rock, Kenneth T. Douglas

Pharmaceutical Science and Research

Quaternization of the nitrogen atom of 2-amino-4-chlorophenyl phenyl sulfide analogues of chlorpromazine improved inhibition ∼40-fold (3′,4′-dichlorobenzyl-[5-chloro-2-phenylsulfan- ylphenylamino)-propyl]-dimethylammonium chloride inhibited trypanothione reductase from Trypanosoma cruzi with a linear competitive Ki value of 1.7 ( 0.2 µM). Molecular modelling explained docking orientations and energies by: (i) involvement of the Z-site hydrophobic pocket (roughly bounded by F396′, P398′, and L399′), (ii) ionic interactions for the cationic nitrogen with Glu-466′ or -467′. A series of N-acyl-2-amino-4-chlorophenyl sulfides showed mixed inhibition (Ki, Ki′ ) 11.3-42.8 µM). The quaternized analogues of the 2-chlorophenyl phenylsulfides had strong antitrypanosomal and antileishmanial activity in vitro against T. bruceirhodesiense STIB900, …