Natural pentacyclic triterpenoid as allosteric modulators of human 5-lipoxygenase with potential anti-inflammatory activity.

This study explored new methods to inhibit human 5-lipoxygenase (5-hLOX) by analyzing natural terpenes that share structural similarities with acetoxyboswellic acid (AKBA). Enzymatic assays were used to evaluate the terpene's ability to inhibit the enzyme, potentially providing anti-inflammatory benefits. Our research focused on how certain types of triterpenes can inhibit 5-hLOX allosterically via a newly discovered allosteric site identified by enzyme crystallization. To determine whether natural boswellic acid analogs mimicked the allosteric known inhibitor AKBA, we combined 5-hLOX inhibition with in silico modeling. Our research has discovered that certain amino acids, specifically Arg 138, Arg 101, Arg 68, and Gln129, located in the allosteric 5-hLOX pocket, play a critical role in stabilizing glycyrrhetinic isomers. These amino acids form hydrogen bonds and hydrophobic interactions that contribute to the inhibitory potency of boswellic acid derivatives. We have found that α and ß glycyrrhetinic acid isomers, carbenoxolone, and to a minor extent, prednisolone, have a potent inhibitory effect against 5-hLOX with IC50 values of 8.64, 3.94, 52.98, and 291.20 µM, respectively. These values are in line with our calculated in silico allosteric site binding energy estimations. In contrast, other steroidal or non-steroidal anti-inflammatory agents exhibited inhibitory potencies larger than 500 µM. However, the specific pharmacodynamic mechanisms are currently unknown. We propose that AKBA analogs may lead to the future development of novel anti-inflammatory agents.Communicated by Ramaswamy H. Sarma.

Biological activities of 4H-thiochromen-4-one 1,1-dioxide derivatives against tropical disease parasites: A target-based drug design approach.

A promising strategy for developing novel therapies against tropical diseases, including malaria, leishmaniasis, and trypanosomiasis, is to detect biological targets such as trypanothione reductase, a vital parasite enzyme that regulates oxidative stress. This enzyme is highly selective and conserved in the Trypanosotidae family and has an ortholog in the Plasmodium genus. Previous studies have established that an isosteric replacement of naphthoquinone's carbonyl group with a sulfone group leads to compounds with high bioactivity and selectivity (half-maximal inhibitory concentration = 3 µM against intracellular amastigotes of L. panamensis, selectivity index = 153 over monocytes U-937). In this study, we analyzed the reactive oxygen species (ROS) levels of parasites through indirect measurements of the tryparedoxin system after treatment with these isosteric compounds. This strategy proved that a significant increase in the ROS levels and strong mitochondrial perturbation led to the death of parasites due to cell homeostatic imbalance, confirming the compounds' effectiveness in disrupting this important metabolic pathway. To improve understanding of the parasite-molecule interaction, 27 new compounds were synthesized and assessed against parasites of the three principal tropical diseases (malaria, leishmaniasis, and trypanosomiasis), displaying an EC50 below 10 µM and good correlation with in-silico studies, indicating that the 4H-thiochromen-4-one 1,1-dioxide core is a special allosteric modulator. It can interact in the binding pocket through key amino acids like Ser-14, Leu-17, Trp-21, Ser-109, Tyr-110, and Met-113, leading to interhelical disruption.

Anticancer potential of mebendazole against chronic myeloid leukemia: in silico and in vitro studies revealed new insights about the mechanism of action.

Chronic myeloid leukemia (CML) is caused by constitutively active fusion protein BCR-ABL1, and targeting ABL1 is a promising therapy option. Imatinib, dasatinib, and nilotinib have all been shown to work effectively in clinical trials. ABL1 mutations, particularly the T315I gate-keeper mutation, cause resistance in patients. As a result, broad-spectrum ABL1 medicines are desperately needed. In order to screen potential drugs targeting CML, mebendazole (MBZ) was subjected to the in vitro test against CML cell lines (K562 and FEPS) and computational assays. The antiproliferative effect of MBZ and the combination with tyrosine kinase inhibitors (TKIs) was tested using end-point viability assays, cell cycle distribution analysis, cell membrane, and mitochondrial dyes. By interrupting the cell cycle and causing cell death, MBZ and its combination with imatinib and dasatinib have a significant antiproliferative effect. We identified MBZ as a promising "new use" drug targeting wild-type and mutant ABL1 using molecular docking. Meanwhile, we determined which residues in the allosteric site are important in ABL1 drug development. These findings may not only serve as a model for repositioning current authorized medications but may also provide ABL1-targeted anti-CML treatments a fresh lease of life.

Computational Design of Inhibitors Targeting the Catalytic ß Subunit of Escherichia coli FOF1-ATP Synthase.

With the uncontrolled growth of multidrug-resistant bacteria, there is an urgent need to search for new therapeutic targets, to develop drugs with novel modes of bactericidal action. FoF1-ATP synthase plays a crucial role in bacterial bioenergetic processes, and it has emerged as an attractive antimicrobial target, validated by the pharmaceutical approval of an inhibitor to treat multidrug-resistant tuberculosis. In this work, we aimed to design, through two types of in silico strategies, new allosteric inhibitors of the ATP synthase, by targeting the catalytic ß subunit, a centerpiece in communication between rotor subunits and catalytic sites, to drive the rotary mechanism. As a model system, we used the F1 sector of Escherichia coli, a bacterium included in the priority list of multidrug-resistant pathogens. Drug-like molecules and an IF1-derived peptide, designed through molecular dynamics simulations and sequence mining approaches, respectively, exhibited in vitro micromolar inhibitor potency against F1. An analysis of bacterial and Mammalia sequences of the key structural helix-turn-turn motif of the C-terminal domain of the ß subunit revealed highly and moderately conserved positions that could be exploited for the development of new species-specific allosteric inhibitors. To our knowledge, these inhibitors are the first binders computationally designed against the catalytic subunit of FOF1-ATP synthase.

Binding sites and hydrophobic pockets in Human Thioredoxin 1 determined by normal mode analysis.

The Thioredoxin (Trx) system plays important roles in several diseases (e.g. cancer, viral infections, cardiovascular and neurodegenerative diseases). Therefore, there is a therapeutic interest in the design of modulators of this system. In this work, we used normal mode analysis to identify putative binding site regions for Human Trx1 that arise from global motions. We identified three possible inhibitor's binding regions that corroborate previous experimental findings. We show that intrinsic motions of the protein are related to the exposure of hydrophobic regions and non-active site cysteines that could constitute new binding sites for inhibitors.