Taurine compared to inhibitors of myeloperoxidase (MPO) as protective agents against low density lipoprotein modification by enzymatically generated hypochlorous acid

Background & Objective: Taurine is a sulfur amino acid that protects   cells from self-destruction during oxidative processes, such as chlorinated oxidants (hypochlorous acid, HOCl). Our objective was to compare the effects of taurine with myeloperoxidase inhibitors (MPO) on the process of HOCL-induced low density lipoprotein (LDL) changes. 

Materials & Methods:  We assessed the serum of some blood donors with normal serum lipid levels. We evaluated  1) blocking  the neutrophil function by preventing oxidant production by MPO with 3-amino 1,2,4 triazole,  potassium cyanide, sodium azide,  P-hydroxy-benzoic acid hydrazide (pHBAH),  Salicylhydroxamic acid, and benzohydroxarnic acid; 2) trapping of products of activated neutrophils,such as MPO- derived HOCl by taurine , methionine and glycine.   Tryptophan destruction in presence of the MPO system was monitored fluorimetrically as a marker of LDL modification. 

Results: At a taurine concentration of 40 pM, which is three orders of magnitude below the physiological value, t_max2 was increased by a factor of 50 compared to the control in absence of taurine (20 min versus 0.4 min). P-hydroxy-benzoic acid hydrazide (pHBAH), at a concentration o f 0.3 to 0.75 MM, too, was a potent inhibitor of   tryptophan destruction.

Discussion: This study suggests a high potential of taurine to slow down inflammatory processes by modulating the oxidative burst of neutrophils. Taurine was the second most potent netralizer of HOCL, after methionine. Taurine may be used to prevent oxidant damage to neutrophills.