On the molecular and cellular effects of omeprazole to further support its effectiveness as an antigiardial drug

Abstract

Research on Giardia lamblia has accumulated large information about its molecular cell biology and infection biology. However, giardiasis is still one of the commonest parasitic diarrheal diseases affecting humans. Additionally, an alarming increase in cases refractory to conventional treatment has been reported in low prevalence settings. Consequently, efforts directed toward supporting the efficient use of alternative drugs, and the study of their molecular targets appears promising. Repurposing of proton pump inhibitors is effective in vitro against the parasite and the toxic activity is associated with the inhibition of the G. lamblia triosephosphate isomerase ( Gl TIM) via the formation of covalent adducts with cysteine residue at position 222. Herein, we evaluate the effectiveness of omeprazole in vitro and in situ on Gl TIM mutants lacking the most superficial cysteines. We studied the influence on the glycolysis of Giardia trophozoites treated with omeprazole and characterized, for the first time, the morphological effect caused by this drug on the parasite. Our results support the effectiveness of omeprazole against Gl TIM despite of the possibility to mutate the druggable amino acid targets as an adaptive response. Also, we further characterized the effect of omeprazole on trophozoites and discuss the possible mechanism involved in its antigiardial effect.

Deamidated Human Triosephosphate Isomerase is a Promising Druggable Target

“…The in situ inactivation of N16D HsTIM with a thiol-reactive drug such as omeprazole might be linked to the accumulation of TIM metabolites, as occurred in other cell models [26]. This is the case for DHAP, one of the substrates of TIM, which in turn can be spontaneously degraded to the toxic metabolite MGO.…”

“…Next, the supernatant was collected and stored at −70 • C for further measurement. To quantify the free MGO from bacterial cells, standard values of MGO were determined according to the method described by Gilbert and Brandt [25] with modifications [26]. Stock solutions of 20 mM 2,4-dinitrophenylhydrazine (DNPH) in HCl-ethanol (12:88) and 1 mM MGO in distilled water were prepared.…”

“…Because MGO is irreversibly bound to DNA and proteins (mostly to proteins) [27], advanced glycation end products (AGEs) were measured with the AGE ELISA Kit (MBS267540, MyBioSource, San Diego, CA, USA), according to the manufacturer's instructions with modifications [26]. A precoated antibody was used as the AGE monoclonal antibody, and the detection antibody was a biotin-labeled polyclonal antibody.…”

Enhanced Antigiardial Effect of Omeprazole Analog Benzimidazole Compounds

“…Recently, it has been reported that 2mercaptobenzimidazole-derived compounds possess antiparasitic properties [18][19][20]. Interestingly, one of the compounds that has the benzimidazole ring in its structure is omeprazole, which has been studied for its antigiardial properties [12,14,17,21,22]. Furthermore, it has been observed that…”

“…Recently, it has been reported that 2-mercaptobenzimidazole-derived compounds possess antiparasitic properties [18][19][20]. Interestingly, one of the compounds that has the benzimidazole ring in its structure is omeprazole, which has been studied for its antigiardial properties [12,14,17,21,22]. Furthermore, it has been observed that omeprazole and certain analogs exhibit antigiardial activity, because these compounds act as inhibitors of the glycolytic enzyme triosephosphate isomerase (TPI) of Giardia lamblia by covalent binding of benzimidazole moiety with cysteine residues [17], suggesting that this enzyme could be proposed as a potential drug target in the antigiardial activity of these compounds [12].…”