Kinetic and Molecular Docking Studies to Determine the Effect of Inhibitors on the Activity and Structure of Fused G6PD::6PGL Protein from Trichomonas vaginalis

Abstract

Trichomoniasis is a sexually transmitted disease with a high incidence worldwide, affecting 270 million people. Despite the existence of a catalog of available drugs to combat this infection, their extensive use promotes the appearance of resistant Trichomonas vaginalis (T. vaginalis), and some side effects in treated people, which are reasons why it is necessary to find new alternatives to combat this infection. In this study, we investigated the impact of an in-house library comprising 55 compounds on the activity of the fused T. vaginalis G6PD::6PGL (TvG6PD::6PGL) protein, a protein mediating the first reaction step of the pentose phosphate pathway (PPP), a crucial pathway involved in the parasite’s energy production. We found four compounds: JMM-3, CNZ-3, CNZ-17, and MCC-7, which inhibited the TvG6PD::6PGL protein by more than 50%. Furthermore, we determined the IC50, the inactivation constants, and the type of inhibition. Our results showed that these inhibitors induced catalytic function loss of the TvG6PD::6PGL enzyme by altering its secondary and tertiary structures. Finally, molecular docking was performed for the best inhibitors, JMM-3 and MCC-7. All our findings demonstrate the potential role of these selected hit compounds as TvG6PD::6PGL enzyme selective inhibitors.

Imidazole Carbamates as a Promising Alternative for Treating Trichomoniasis: In Vitro Effects on the Growth and Gene Expression of Trichomonas vaginalis

“…The PPP is a key metabolic route and, as such, it has been proposed as a strategic pathway for discovery of targets in drug design [ 26 ]. Furthermore, the G6PD:6PGL enzyme has been proposed as a potential pharmacological target for the design of drugs in parasites such as T. vaginalis , G. lamblia , and P. falciparum [ 27 , 28 , 29 ]. Due to the importance of the PPP in T. vaginalis , compounds that alter the expression of genes such as G6PD::6PGL are crucial therapeutic candidates, since, by negatively impacting expression, they also directly alter essential biological processes such as proliferation.…”

Fused Enzyme Glucose-6-Phosphate Dehydrogenase::6-Phosphogluconolactonase (G6PD::6PGL) as a Potential Drug Target in Giardia lamblia, Trichomonas vaginalis, and Plasmodium falciparum

“…In this way, enzyme inhibitors can be discovered, and since these enzymes are vital for the target pathogen, their inhibition would lead to its demise. In this regard, various studies have been conducted to assess the inhibitory effect of chemical libraries on the fused G6PD::6PGL enzyme of the parasites P. falciparum , G. lamblia , and T. vaginalis [ 37 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 ]. In these studies, molecules that inhibit the enzymatic activity of the G6PD domain in the recombinant G6PD::6PGL enzyme have been identified.…”

“…In a recent study by Martínez-Rosas et al [ 115 ], it was discovered that the drug nitazoxanida acts as a catalytic inhibitor of the fused GlG6PD::6PGL enzyme in T. vaginalis , with a k 2 value of 1.78 M −1 s −1 . Consequently, the researchers proposed GlG6PD::6PGL as a new target for the drug nitazoxanida.…”

“…Finally, a study conducted by Martínez-Rosas et al [ 115 ], investigated the impact of a small library of 55 compounds on the activity of the fused T. vaginalis G6PD::6PGL enzyme, in which four compounds showed they could inhibit the enzyme. Three of these compounds are derivatives of nitazoxanida (CNZ-3, CNZ-17, and MCC-7), while the fourth compound is of the carboxylic acid type (JMM-3).…”

“…CNZ-3 and MCC-7 exhibited non-competitive-type inhibition for the G6P substrate, whereas CNZ-17 and JMM-3 demonstrated uncompetitive-type inhibition for G6P. Furthermore, for the NADP + substrate, CNZ-3 showed competitive inhibition, while CNZ-17, MCC-7, and JMM-3 revealed uncompetitive-type inhibition [ 115 ].…”