<i>In vitro</i> effects of sodium benzoate on the activities of aspartate and alanine amino transferases, and alkaline phosphatase from human erythrocytes of different genotypes

Abstract

The in vitro effects of varying concentrations sodium benzoate on the activities of aspartate (E.C. 2.6.1.1) and alanine (E.C. 2.6.1.2) aminotransferases (AST and ALT, respectively) and alkaline phosphatase (E.C. 3.1.3.1; abbreviated as ALP) from human erythrocytes of different genotypes (HbAA, HbAS and HbSS) were investigated. The enzyme activities were measured in the absence and presence of five concentrations (from 0.03 to 0.21 %) of sodium benzoate using erythrocyte preparations from the three genotypes. The results showed significant (p<0.05) inhibition of the three enzymes from the erythrocytes of HbAA, HbAS and HbSS genotypes by sodium benzoate. The compound at 0.1% (the recommended concentration used for preservation) significantly decreased (p<0.05) the activity of HbAA erythrocyte AST to about 93.8 % of the control (no sodium benzoate). HbAS erythrocyte AST showed a significant decrease in activity (p<0.05) to about 95.0 % of the control, while for HbSS erythrocyte AST activity, a significant decrease (p<0.05) to 93.8% of control was observed. For ALT, sodium benzoate (0.1%) significantly (p<0.05) reduced the activity for the HbAA erythrocyte enzyme to 93.3% of the control (no sodium benzoate). HbAS erythrocyte ALT showed a significant decrease in activity (p<0.05) at 93.4% of control, while the activity for HbSS erythrocyte ALT significantly p<0.05) decreased to 95.4 % of the control. At 0.1%, sodium benzoate decreased the activity of HbAA erythrocyte ALP significantly (p<0.05) by 9.7% of the control. For HbAS erythrocyte ALP, the activity significantly decreased (p<0.05) to about 91.7% of control, while for HbSS erythrocyte ALP, a significant decrease (p<0.05) in the activity to 91.3% of control was noted. The findings of significant decreases in the activities of AST, ALT and ALP from the different genotypes in the presence of sodium benzoate have far-reaching implications to the use of sodium benzoate as a preservative. It is plausible that the biochemical activities such as amino acid metabolism (amino transferases) and phosphate/lipid metabolism (alkaline phosphatase) performed by these enzymes may be impaired by unregulated consumption of products containing sodium benzoate, suggesting care in the use of this preservative.

Key words: sodium benzoate, aminotransferases, erythrocytes, phosphatase

Biokemistri Vol.17(1) 2005: 33-38