Repositioning of Small Molecules through the Inverse Virtual Screening in silico Tool: Case of Benzothiazole-Based Inhibitors of Soluble Epoxide Hydrolase (sEH)

Computational techniques accelerate drug discovery by identifying bioactive compounds for specific targets, optimizing molecules with moderate activity, or facilitating the repositioning of inactive items onto new targets. Among them, the Inverse Virtual Screening (IVS) approach is aimed at the evaluation of one or a small set of molecules against a panel of targets for addressing target identification. In this work, a focused library of benzothiazole-based compounds was re-investigated by IVS. Four items, originally synthesized and tested on bromodomain-containing protein 9 (BRD9) but yielding poor results, were critically re-analyzed, disclosing only a partial fit with 3D structure-based pharmacophore models, which, in the meanwhile, were developed for this target. Afterwards, these compounds were re-evaluated through IVS on a panel of proteins involved in inflammation and cancer, identifying soluble epoxide hydrolase (sEH) as a putative interacting target. Three items were subsequently confirmed as able to inhibit sEH activity, spanning from 70% up to 30% when tested at 10 μM. Finally, one benzothiazole-based compound emerged as the most promising inhibitor featuring an IC50 in the low micromolar range (IC50 = 6.62 ± 0.13 μM). Our data confirm IVS as a predictive tool for accelerating the target identification and repositioning processes.

Mycobacterium tuberculosis-Induced Prostaglandin J2 and 15-Deoxy-Prostaglandin J2 Inhibit Inflammatory Signals in Human M1 Macrophages via a Negative Feedback Loop

Tuberculosis caused by Mycobacterium tuberculosis is a leading cause of death globally and a major health concern. In humans, macrophages are the first line invaded by M. tuberculosis. Upon infection, macrophages upregulate cyclooxygenase-2 (COX-2) expression and consequently elevate the formation of PGs, including PGE2 and PGD2. Although the role of proinflammatory PGE2 in M. tuberculosis infection has been reported, the roles of PGJ2 and 15-deoxy-PGJ2 (collectively named J2-PGs), the metabolites of PGD2 with anti-inflammatory features, remain elusive. In this study, we show that M. tuberculosis (H37Rv strain)-conditioned medium stimulates human monocyte-derived macrophages (MDMs) to elevate COX-2 expression along with robust generation of PGJ2, exceeding PGD2 formation, and to a minor extent also of 15-deoxy-PGJ2. Of interest, in M1-MDM phenotypes, PGJ2 and 15-deoxy-PGJ2 decreased M. tuberculosis (H37Rv strain)-conditioned medium-induced COX-2 expression and related PG formation by a negative feedback loop. Moreover, these J2-PGs downregulated the expression of the proinflammatory cytokines IL-6, IL-1β, and IFN-γ, but elevated the anti-inflammatory cytokine IL-10 and the M2 markers arginase-1 and CD163. These anti-inflammatory effects of J2-PGs in M1-MDM correlated with impaired activation of TGF-β-activated kinase 1/NF-κB/MAPK pathways. Finally, we found that J2-PGs regulate COX-2 expression, at least partially, via PGD2 receptor (DP1) and chemoattractant receptor homologue expressed on Th2 cells/DP2 receptors, but independent of the J2-PG receptor peroxisome proliferator-activated receptor-γ. Together, our findings reveal that M. tuberculosis induces COX-2 expression in human M1-MDMs, along with robust formation of J2-PGs that mediates anti-inflammatory effects via a negative feedback loop.

Identification of 2,4-Dinitro-Biphenyl-Based Compounds as MAPEG Inhibitors

We identified 2,4-dinitro-biphenyl-based compounds as new inhibitors of leukotriene C₄ synthase (LTC₄ S) and 5-lipoxygenase-activating protein (FLAP), both members of the "Membrane Associated Proteins in Eicosanoid and Glutathione metabolism" (MAPEG) family involved in the biosynthesis of pro-inflammatory eicosanoids. By molecular docking we evaluated the putative binding against the targets of interest, and by applying cell-free and cell-based assays we assessed the inhibition of LTC₄ S and FLAP by the small molecules at low micromolar concentrations. The present results integrate the previously observed inhibitory profile of the tested compounds against another MAPEG member, i. e., microsomal prostaglandin E₂ synthase (mPGES)-1, suggesting that the 2,4-dinitro-biphenyl scaffold is a suitable molecular platform for a multitargeting approach to modulate pro-inflammatory mediators in inflammation and cancer treatment.

Natural chalcones elicit formation of specialized pro-resolving mediators and related 15-lipoxygenase products in human macrophages

Specialized pro-resolving mediators (SPMs) comprise lipid mediators (LMs) produced from polyunsaturated fatty acids (PUFAs) via stereoselective oxygenation particularly involving 12/15-lipoxygenases (LOXs). In contrast to pro-inflammatory LMs such as leukotrienes formed by 5-LOX and prostaglandins formed by cyclooxygenases, the SPMs have anti-inflammatory and inflammation-resolving properties. Although glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs) that block prostaglandin production are still prime therapeutics for inflammation-related diseases despite severe side effects, novel concepts focus on SPMs as immunoresolvents for anti-inflammatory pharmacotherapy. Here, we studied the natural chalcone MF-14 and the corresponding dihydrochalcone MF-15 from Melodorum fruticosum, for modulating the biosynthesis of LM including leukotrienes, prostaglandins, SPM and their 12/15-LOX-derived precursors in human monocyte-derived macrophage (MDM) M1- and M2-like phenotypes. In MDM challenged with Staphylococcus aureus-derived exotoxins both compounds (10 µM) significantly suppressed 5-LOX product formation but increased the biosynthesis of 12/15-LOX products, especially in M2-MDM. Intriguingly, in resting M2-MDM, MF-14 and MF-15 strikingly evoked generation of 12/15-LOX products and of SPMs from liberated PUFAs, along with translocation of 15-LOX-1 to membranous compartments. Enhanced 12/15-LOX product formation by the chalcones was evident also when exogenous PUFAs were supplied, excluding increased substrate supply as sole underlying mechanism. Rather, MF-14 and MF-15 stimulate the activity of 15-LOX-1, supported by experiments with HEK293 cells transfected with either 5-LOX, 15-LOX-1 or 15-LOX-2. Together, the natural chalcone MF-14 and the dihydrochalcone MF-15 favorably modulate LM biosynthesis in human macrophages by suppressing pro-inflammatory leukotrienes but stimulating formation of SPMs by differential interference with 5-LOX and 15-LOX-1.

Learning from Nature: From a Marine Natural Product to Synthetic Cyclooxygenase-1 Inhibitors by Automated De Novo Design

The repertoire of natural products offers tremendous opportunities for chemical biology and drug discovery. Natural product-inspired synthetic molecules represent an ecologically and economically sustainable alternative to the direct utilization of natural products. De novo design with machine intelligence bridges the gap between the worlds of bioactive natural products and synthetic molecules. On employing the compound Marinopyrrole A from marine Streptomyces as a design template, the algorithm constructs innovative small molecules that can be synthesized in three steps, following the computationally suggested synthesis route. Computational activity prediction reveals cyclooxygenase (COX) as a putative target of both Marinopyrrole A and the de novo designs. The molecular designs are experimentally confirmed as selective COX-1 inhibitors with nanomolar potency. X-ray structure analysis reveals the binding of the most selective compound to COX-1. This molecular design approach provides a blueprint for natural product-inspired hit and lead identification for drug discovery with machine intelligence.

Isolation of the Thogoto virus from a Haemaphysalis longicornis in Kyoto City, Japan

Ticks transmit viruses responsible for severe emerging and re-emerging infectious diseases, some of which have a significant impact on public health. In Japan, little is known about the distribution of tick-borne viruses. In this study, we collected and tested ticks to investigate the distribution of tick-borne arboviruses in Kyoto, Japan, and isolated the first Thogoto virus (THOV) to our knowledge from Haemaphysalis longicornis in far-eastern Asia. The Japanese isolate was genetically distinct from a cluster of other isolates from Africa, Europe and the Middle East. Various cell lines derived from mammals and ticks were susceptible to the isolate, but it was not pathogenic in mice. These results advance understanding of the distribution and ecology of THOV.