Activation of human erythrocyte glutathione – s – transferase (EC.2.5.1.18) by some antihistamines

Abstract

Various concentrations (0.05mg%, 0.10mg%, 0.20mg%, 0.30mg%, 0.40mg% and 0.50mg%) of each of the antihistamines – cyproheptadine, chlorpheniramine and klemastin (all H – 1 antagonists), were tested on their possible effect on human erythrocyte (red cell) glutathione – S – transferase (EC. 2.5.1.18) activity. The result indicated significant (P< 0.001) activation of the red cell enzyme by all the H – 1 antagonists according to the order: Chlorpheniramine > Cyproheptadine> klemastin.


The activation of human erythrocyte glutathione S – transferase (GST) by the antihistamines was also observed to be concentration – dependent i.e. higher concentrations produced greater activation of the enzyme. For instance, at cyproheptadine concentrations of 0.20mg% and 0.30mg%, red cell GST activity was increased by 4.99 folds (498.85%) and 6.98 folds (694.28%) respectively. Similarly, at the same concentrations (0.20mg% and 0.30mg%), klemastin activated human erythrocyte GST by 2.87 fold (387.36%) and 3.59 fold (359.20%) respectively, while chlorpheniramine produced activations of 7.82 fold (782.18%) and 8.93 fold (893.10%) respectively.


These results may point to a possible binding-deterioration of these drugs by the human erythrocyte GST.


Global Jnl Medical Sciences Vol.2(2) 2003: 141-144