Isolation and Purification of Entamoeba histolytica Alcohol Dehydrogenase 2 (EhADH2) Enzymatic Activities and Inhibition by Pyrazoline Derivatives

Abstract

The bifunctional alcohol/ aldehyde dehydrogenase enzyme in Entamoeba histolytica (EhADH2) belongs to the ADHE iron dependent family, and is essential for trophozoite growth and survival. EhADH2 catalyzes the conversion of acetyl Co‐A to acetaldehyde and the final reduction of acetaldehyde to ethanol by its separate ADH and ALDH domains respectively. The primary focus of research was to determine the effect of alternative treatments for amebiasis through inhibition by pyrazoline inhibitors on the EhADH2 enzyme. Series 1a (1,3‐diphenyl‐1‐carbamoyl‐2‐pyrazoline), series 1b (3‐diphenyl‐1‐propylcarbamoyl‐2‐pyrazoline), series 2 (1,3,4‐triphenyl‐1‐carbamoyl‐2‐pyrazoline), pyrazoline derivatives showed capabilities to inhibit EhADH2 activities. A kinetic assay was performed to calculate the Ki value for inhibitor [3‐(4‐chlorophenyl)‐1‐(bromophenylcarboxamide)‐2‐pyrazoline], inhibitor [3‐4(‐chlorophenyl)‐1‐N‐propylcarboxamide‐2‐pyrazoline], and inhibitor [3‐(4‐cholorphenyl)‐4‐phenyl‐1‐(4‐chlorophenyl carboxamide)‐2‐pyrazoline] at the rate of enzymatic affinity with the substrate acetaldehyde at NAD+ μM/min as the unit of measurement; then, the Ki value for the inhibitor was calculated using Michaelis‐Menten and Lineweaver‐Burke equations. Inhibitor [3‐(4‐chlorophenyl)‐4‐phenyl‐1‐(4‐chlorophenyl carboxamide)‐2‐pyrazoline], from series 2, demonstrated higher inhibition of EhADH2 enzymatic activities compared to series 1a and 1b. Future modifications to the basic structures of the three series shall improve the efficiency of these compounds.

Entamoeba histolytica: Membrane and Non-Membrane Protein Structure, Function, Immune Response Interaction, and Vaccine Development

“…Furthermore, EhADH2 is similar to other protist and bacterial bifunctional enzymes, as suggested by the phylogenetic tools [106]. This enzyme plays a role in catalyzing the conversion of acetyl CoA to acetaldehyde and the final reduction of acetaldehyde to ethanol [106,107,109]. It was also suggested by Adeoti et al (2021) [97] as a vaccine candidate, based on bioinformatic analyses using GEPTOP CELLO NCBI.…”