Structure-guided inhibitor design targeting CntL provides the first chemical validation of the staphylopine metallophore system in bacterial metal acquisition.

To survive in the metal-scarce environment within the host, pathogens synthesize various small molecular metallophores to facilitate the acquisition of transition metals. The cobalt and nickel transporter (Cnt) system synthesizes and transports staphylopine, a nicotianamine-like metallophore, and serves as a primary transition metal uptake system in Gram-positive bacteria including the human pathogen Staphylococcus aureus. In this study, we report the design of the first inhibitor of the Cnt system by targeting the key aminobutanoyltransferase CntL which is involved in the biosynthesis of staphylopine. Through structure-guided fragment linking and optimization, a class of acceptor-adenosine dual-site inhibitors against S. aureus CntL (SaCntL) were designed and synthesized. The most potent inhibitor, compound 9, demonstrated a ΔTm value of 9.4 °C, a Kd value of 0.021 ± 0.004 µM, and an IC50 value of 0.06 µM against SaCntL. The detailed mechanism by which compound 9 inhibits SaCntL has been elucidated through a high-resolution co-crystal structure. Treatment with compound 9 resulted in a moderate downregulation of intracellular concentrations of iron, nickel, and cobalt ions in the S. aureus cells cultured in the metal-scarce medium, providing the first chemical validation of the important role of Cnt system in bacterial metal acquisition. Our findings pave the way for the development of CntL-based antibacterial agents in future.

Porcine stomach surgical simulation model for cesarean section and cervical laceration suturing.

BACKGROUND: Junior OB/GYN residents lack opportunities for fundamental surgical skills training of cesarean section, and most OB/GYN residents lack the experience of cervical laceration suturing due to its low incidence. METHODS: A porcine stomach simulation model was designed for obstetrics surgical training. The surface of the stomach simulated the uterus, and the pylorus and cardia simulated the cervical canal. EXPERIENCE: Materials are available from the nearby market. The total cost of the model isï¿¥41. This model can be used in the training in uterus incision and repair of cesarean section and training in cervical laceration suturing. CONCLUSION: The porcine stomach simulation model is pragmatic and realistic. They can be applied in the OB/GYN skill courses to introduce the fundamental obstetrics process to medical students and residents.

Discovery of Novel Antiosteoporosis Leads with Bone Resorption Inhibition and Anabolic Promotion through a Chemotype-Assembly Approach.

Developing a dual-efficiency agent with antiresorptive and anabolic applications is a promising strategy for treating osteoporosis. This study reports the discovery of dual antiosteoporosis agents via a chemotype-assembly approach. Chemotype analysis identified 12 antiresorptive and 12 anabolic chemotypes and 7 dual-function chemotype-assembly rules. Based on these assembly rules, a dual-functional compound S24 was discovered. S24 exhibits osteoclastogenesis inhibition with an IC50 value of 10.28 µM and osteoblast differentiation stimulation at 10 µM. S24 derivatives were designed and synthesized based on the activity relationship of the chemotypes. This yielded a more active compound, S24-14, with an osteoclastogenesis inhibition IC50 value of 0.40 µM and osteoblast differentiation stimulation at 1.0 µM; compound S24-14 also suppressed bone loss in vivo. These results prove that S24-14 can be a potential lead for antiosteoporosis drug development.

Discovery of Novel Neo-Clerodane Derivatives as Potent Dual-Functional Antiosteoporosis Agents through Targeting Peroxisome Proliferator-Activated Receptor-γ.

A library of 31 natural neo-clerodanes isolated from Ajuga decumbens was assayed for antiosteoporosis. This results in 18 neo-clerodane osteoclastogenesis inhibitors, and compound 3 prevents bone loss in vivo. Further mechanistic studies demonstrated that these compounds inhibit osteoporosis by antagonizing peroxisome proliferator-activated receptor-γ (PPARγ). We designed and synthesized 17 compounds by chemically modifying the natural neo-clerodane 19 (highly potent and the major composition of A. decumbens extract) by means of structure-based drug design techniques. Among these neo-clerodane derivatives, compound 34 is the most potent osteoporosis inhibitor with a 46-fold improvement in inhibiting osteoclastogenesis (IC50 = 0.042 vs 1.92 µM), 11-fold increased activity in PPARγ antagonism (EC50 = 0.75 vs 8.35 µM), 66-fold enhancement in receptor affinity (KD = 0.27 vs 17.7 µM), and enhanced osteogenic promotion compared to 19. This underscores the potential of neo-clerodane diterpenoids as promising leads for osteoporosis treatment by targeting PPARγ.

Targeting ferritinophagy impairs quiescent cancer stem cells in acute myeloid leukemia in vitro and in vivo models.

Acute myeloid leukemia (AML) remains a challenging hematological malignancy with poor prognosis and limited treatment options. Leukemic stem cells (LSCs) contribute to therapeutic failure, relapse, and adverse outcome. This study investigates the role of quiescence and related molecular mechanisms in AML pathogenesis and LSC functions to identify potential therapeutic targets. Transcriptomic analysis revealed that the LSC-enriched quiescent cell population has a distinct gene signature with prognostic relevance in patients with AML. Mechanistically, quiescent blasts exhibit increased autophagic activity, which contributes to their sustained viability. Proteomic profiling uncovered differential requirements for iron metabolism between quiescent and cycling cells, revealing a unique dependence of quiescent cells on ferritinophagy, a selective form of autophagy mediated by nuclear receptor coactivator 4 (NCOA4), which regulates iron bioavailability. We evaluated the therapeutic potential of inhibiting NCOA4-mediated ferritinophagy using genetic knockdown and chemical inhibition approaches. In vitro assays showed that suppression of NCOA4 was toxic to leukemic blasts, particularly the CD34+CD38- LSC-enriched population, without affecting normal CD34+ hematopoietic progenitors. In vivo studies using murine patient-derived xenograft (PDX) models of AML confirmed that NCOA4 inhibition reduced tumor burden and impaired LSC viability and self-renewal, indicating a specific vulnerability of these cells to ferritinophagy disruption. Our findings underscore the role of NCOA4-mediated ferritinophagy in maintaining LSC quiescence and function and suggest that targeting this pathway may be an effective therapeutic strategy for AML. This study highlights the potential of NCOA4 inhibition to improve AML outcomes and paves the way for future research and clinical development.

FerroLigandDB: A Ferroptosis Ligand Database of Structure-Activity Relations.

Ferroptosis is an iron-dependent programmed cell death characterized by lipid peroxidation that is linked to the pathophysiological processes in many diseases, such as neurodegenerative diseases, cancers, ischemia-reperfusion injuries, and organ damages. Many proteins are associated with ferroptosis signal transduction pathways. Novel chemical compounds are demanded to explore and regulate these pathways. Therefore, a ferroptosis ligand database, which holds relations among chemical structures, targets, bioactivities, and diseases, is needed for discovering and designing new ferroptosis regulators. This work reports FerroLigandDB, a manually curated database for small-molecular ferroptosis regulators. The database comprises 466 ferroptosis inducer entries (with 380 unique molecular structures) and 539 ferroptosis inhibitor entries (with 468 unique molecular structures) (note: one compound can be recorded as multiple entries due to the different assays). Each ferroptosis ligand entry is detailed with compound IDs, structure attributes, bioactivity values, test objects, target information, associated diseases, and references. The fields in the FerroLigandDB database implicitly contain relationships among chemical structures, bioactivities, targets, and diseases. Thus, FerroLigandDB is a comprehensive resource for scientists to design and discover novel ferroptosis regulators. The user interface of FerroLigandDB is implemented with query features and data visualization facilities. With compound identifiers, the compounds are linked to the records of other chemoinformatics databases (such as PubChem and SciFinder). The FerroLigandDB database is freely accessible at http://ferr.gulab.org.cn/.

dMXP: A De Novo Small-Molecule 3D Structure Predictor with Graph Attention Networks.

Generating the three-dimensional (3D) structure of small molecules is crucial in both structure- and ligand-based drug design. Structure-based drug design needs bioactive conformations of compounds for lead identification and optimization. Ligand-based drug design techniques, such as 3D shape similarity search, 3D pharmacophore model, 3D-QSAR, etc., all require high-quality small-molecule ligand conformations to obtain reliable results. Although predicting a small molecular bioactive conformer requires information from the receptor, a crystal structure of the molecule is a proper approximation to its bioactive conformer in a specific receptor because the binding pose of a small molecule in its receptor's binding pockets should be energetically close to the crystal structures. This study presents a de novo small molecular structure predictor (dMXP) with graph attention networks based on crystal data derived from the Cambridge Structural Database (CSD) combined with molecular electrostatic information calculated by density-functional theory (DFT). Two featuring strategies (topological and atomic partial change features) were employed to explore the relation between these features and the 3D crystal structure of a small molecule. These features were then assembled to construct the holistic 3D crystal structure of a molecule. Molecular graphs were encoded using a graph attention mechanism to deal with the issues of the inconsistencies of local substructures contributing to the entire molecular structure. The root-mean-square deviation (RMSDs) of approximately 80% dMXP predicted structures and the native binding poses within receptors are less than 2.0 Å.

Identification and structural modification of ent-rosane diterpenoids from Euphorbia milii inhibiting RANKL-induced osteoclastogenesis.

Phytochemical study on Euphorbia milii, a common ornamental plant, resulted in the identification of thirteen new ent-rosane diterpenoids (1-13), three new ent-atisane diterpenoids (14-16), and a known ent-rosane (17). Their structures were delineated using spectroscopic data, quantum chemical calculations, and X-ray diffraction experiments. Euphomilone F (1) represented a rare ent-rosane-type diterpenoid with a 5/7/6 skeleton. Euphoainoid G (8) was a rare rosane diterpenic acid. Compounds 9 and 10 carried infrequent tetrahydrofuran rings, and compounds 11-13 was 18-nor-ent-rosane diterpenoids. All isolates were evaluated for their inhibitory effects on RANKL-induced osteoclasts. Notably, compounds with aromatic ester groups (2-7) showed promising activities (IC50 < 10 µM), underscoring the significance of acylated A-ring moieties in the ent-rosane skeleton for anti-osteoclastogenesis. Thirteen synthetic derivatives were obtained through esterification of 17. Of these, compound 27 exhibited remarkable improvement, with an IC50 of 0.8 µM, more than a 12-fold increase in potency compared to the parent compound 17 (IC50 > 10 µM). This work presents a series of new ent-rosane diterpenoids with potential antiosteoporosis agents.

Biochemical and structural characterization of chlorhexidine as an ATP-assisted inhibitor against type 1 methionyl-tRNA synthetase from Gram-positive bacteria.

Methionyl-tRNA synthetase (MetRS) catalyzes the attachment of l-methionine (l-Met) to tRNAMet to generate methionyl-tRNAMet, an essential substrate for protein translation within ribosome. Owing to its indispensable biological function and the structural discrepancies with human counterpart, bacterial MetRS is considered an ideal target for developing antibacterials. Herein, chlorhexidine (CHX) was identified as a potent binder of Staphylococcus aureus MetRS (SaMetRS) through an ATP-aided affinity screening. The co-crystal structure showed that CHX simultaneously occupies the enlarged l-Met pocket (EMP) and the auxiliary pocket (AP) of SaMetRS with its two chlorophenyl groups, while its central hexyl linker swings upwards to interact with some conserved hydrophobic residues. ATP adopts alternative conformations in the active site cavity, and forms ionic bonds and water-mediated hydrogen bonds with CHX. Consistent with this synergistic binding mode, ATP concentration-dependently enhanced the binding affinity of CHX to SaMetRS from 10.2 µM (no ATP) to 0.45 µM (1 mM ATP). While it selectively inhibited two representative type 1 MetRSs from S. aureus and Enterococcus faecalis, CHX did not show significant interactions with three tested type 2 MetRSs, including human cytoplasmic MetRS, in the enzyme inhibition and biophysical binding assays, probably due to the conformational differences between two types of MetRSs at their EMP and AP. Our findings on CHX may inspire the design of MetRS-directed antimicrobials in future.

Chemical Constituents of Ajuga Lupulina and their Anti-Ferroptosis Activity.

Five new compounds (1, 2, 7, 12, and 16), along with fifteen known ones, were isolated from Ajuga lupulina Maxim. Their structures were revealed by analysing spectroscopic data (MS, NMR), and experimental and calculated ECD spectra was used to deduce the absolute configuration. Compound 16, with eight carbon atoms, was firstly isolated from the nature. All the isolates were evaluated for their inhibitory effect on RSL3-induced ferroptosis in HT22 mouse hippocampal neuronal cells. Among them, the abietane-type diterpenoids (7-11) significantly inhibited ferroptosis with EC50 values of 0.83 µM, 2.05 µM, 0.96 µM, 1.47 µM, and 1.19 µM, respectively.

Identifying eleven new ferroptosis inhibitors as neuroprotective agents from FDA-approved drugs.

With increasing evidence that ferroptosis is associated with diverse neurological disorders, targeting ferroptosis offers a promising avenue for developing effective pharmaceutical agents for neuroprotection. In this study, we identified ferroptosis inhibitors as neuroprotective agents from US Food and Drug Administration (FDA)-approved drugs. 1176 drugs have been screened against erastin-induced ferroptosis in HT22 cells, resulting in 89 ferroptosis inhibitors. Among them, 26 drugs showed significant activity with EC50 below10 µM. The most active ferroptosis inhibitor is lumateperone tosylate at nanomolar level. 11 drugs as ferroptosis inhibitors were not reported previously. Further mechanistic studies revealed that their mechanisms of actions involve free radical scavenging, Fe2+ chelation, and 15-lipoxygenase inhibition. Notably, the active properties of some drugs were firstly revealed here. These ferroptosis inhibitors increase the chemical diversity of ferroptosis inhibitors, and offer new therapeutic possibilities for the treatments of related neurological diseases.

A nomogram for predicting sepsis-associated delirium: a retrospective study in MIMIC III.

OBJECTIVE: To develop a nomogram for predicting the occurrence of sepsis-associated delirium (SAD). MATERIALS AND METHODS: Data from a total of 642 patients were retrieved from the Medical Information Mart for Intensive Care (MIMIC III) database to build a prediction model. Multivariate logistic regression was performed to identify independent predictors and establish a nomogram to predict the occurrence of SAD. The performance of the nomogram was assessed in terms of discrimination and calibration by bootstrapping with 1000 resamples. RESULTS: Multivariate logistic regression identified 4 independent predictors for patients with SAD, including Sepsis-related Organ Failure Assessment(SOFA) (p = 0.004; OR: 1.131; 95% CI 1.040 to 1.231), mechanical ventilation (P < 0.001; OR: 3.710; 95% CI 2.452 to 5.676), phosphate (P = 0.047; OR: 1.165; 95% CI 1.003 to 1.358), and lactate (P = 0.023; OR: 1.135; 95% CI 1.021 to 1.270) within 24 h of intensive care unit (ICU) admission. The area under the curve (AUC) of the predictive model was 0.742 in the training set and 0.713 in the validation set. The Hosmer - Lemeshow test showed that the model was a good fit (p = 0.471). The calibration curve of the predictive model was close to the ideal curve in both the training and validation sets. The DCA curve also showed that the predictive nomogram was clinically useful. CONCLUSION: We constructed a nomogram for the personalized prediction of delirium in sepsis patients, which had satisfactory performance and clinical utility and thus could help clinicians identify patients with SAD in a timely manner, perform early intervention, and improve their neurological outcomes.

Atractylodinol prevents pulmonary fibrosis through inhibiting TGF-ß receptor 1 recycling by stabilizing vimentin.

Pirfenidone and nintedanib are only anti-pulmonary fibrosis (PF) drugs approved by the FDA. However, they are not target specific, and unable to modify the disease status. Therefore, it is still desirable to discover more effective agents against PF. Vimentin (VIM) plays key roles in tissue regeneration and wound healing, but its molecular mechanism remains unknown. In this work, we demonstrated that atractylodinol (ATD) significantly inhibits TGF-ß1-induced epithelial-mesenchymal transition and fibroblast-to-myofibroblast transition in vitro. ATD also reduces bleomycin-induced lung injury and fibrosis in mice models. Mechanistically, ATD inhibited TGF-ß receptor I recycling by binding to VIM (KD = 454 nM) and inducing the formation of filamentous aggregates. In conclusion, we proved that ATD (derived from Atractylodes lancea) modified PF by targeting VIM and inhibiting the TGF-ß/Smad signaling pathway. Therefore, VIM is a druggable target and ATD is a proper drug candidate against PF. We prove a novel VIM function that TGF-ß receptor I recycling. These findings paved the way to develop new targeted therapeutics against PF.

Discovery of neo-Clerodane Diterpenoids from Ajuga campylantha as Neuroprotective Agents against Ferroptosis and Neuroinflammation.

Twelve new neo-clerodane diterpenoids, eight undescribed methoxy/ethoxy acetal analogues, and one new nor-iridane monoterpenoid were isolated from Ajuga campylantha. Their structures were elucidated using a combination of spectroscopic data, quantum chemical calculations, and X-ray crystallography. This research reveals the distinctive structural features of A. campylantha diterpenes, including distinct C rings and 4,18-double bonds, distinguishing them from diterpenes of other plants in the Ajuga genus. Compound 2 represents the first example of a 19(5→6)-abeo-clerodane formed through a Wagner-Meerwein rearrangement. The isolated compounds were assessed for their neuroprotective effects against RSL3-induced ferroptosis in HT22 cells and LPS-induced neuroinflammation in BV-2 cells. Notably, compound 7 inhibits ferroptosis (EC50 = 10 µM) with a potentially new mechanism of action. The preliminary structure-activity relationship studies revealed that the furan-clerodane diterpenoids possess potential ferroptosis inhibitory activity, while the lactone-clerodanes do not. This study represents the first report of furan-containing clerodanes within the Ajuga genus, providing fresh insights into the phytochemistry and pharmacological potential of A. campylantha.

Discovery and optimization of olanzapine derivatives as new ferroptosis inhibitors.

Ferroptosis is a new type of cell death associated with many human diseases. It is a new strategy to discover ferroptosis inhibitors for the treatment of ferroptosis-related diseases. Here the FDA-approved drug library containing 1160 molecules was screened for ferroptosis inhibitors in RSL3-induced HT22 mouse hippocampal neuronal cells. As a result, olanzapine showed potent ferroptosis inhibitory activity (EC50 = 1.18 µM). Structural optimization and the structure-activity relationships (SARs) analysis led to the synthesis of 41 new derivatives (4-44) and one known compound 45. Comparing with olanzapine, its derivative 36 showed nearly sixteen-folds improved ferroptosis inhibition and low cytotoxicity (EC50 = 0.074 µM, CC50 = 18.8 µM). Further mechanistic studies revealed that compound 36 specifically inhibited ferroptosis by its antioxidative ability. This work demonstrates that olanzapine protected RSL3-induced ferroptosis in HT22 cell, and its derivative 36 having nanomolar ferroptosis inhibitory activity merit to be developed for drugs against ferroptosis-related neurological diseases.

Chemical constituents of Ajuga forrestii and their anti-ferroptosis activity.

Six new neoclerodane diterpenoids (1-6), along with ten known compounds (7-16), were isolated from Ajuga forrestii. Their structures were elucidated by HRESIMS, 1D and 2D NMR, ECD calculation, and single-crystal X-ray diffraction analysis. The structure of a known neoclerodane diterpene ajudecunoid C (6) was revised based on the reported NMR empirical rules. All the isolates were evaluated for their inhibitory effect on RSL3-induced ferroptosis in HT22 mouse hippocampal neuronal cells. Among them, compounds 8, 9, and 12 significantly inhibited RSL3-induced ferroptosis with EC50 values of 0.45 µM, 0.076 µM, and 0.14 µM.

The binding mode of orphan glycyl-tRNA synthetase with tRNA supports the synthetase classification and reveals large domain movements.

As a class of essential enzymes in protein translation, aminoacyl-transfer RNA (tRNA) synthetases (aaRSs) are organized into two classes of 10 enzymes each, based on two conserved active site architectures. The (αß)2 glycyl-tRNA synthetase (GlyRS) in many bacteria is an orphan aaRS whose sequence and unprecedented X-shaped structure are distinct from those of all other aaRSs, including many other bacterial and all eukaryotic GlyRSs. Here, we report a cocrystal structure to elucidate how the orphan GlyRS kingdom specifically recognizes its substrate tRNA. This structure is sharply different from those of other aaRS-tRNA complexes but conforms to the clash-free, cross-class aaRS-tRNA docking found with conventional structures and reinforces the class-reconstruction paradigm. In addition, noteworthy, the X shape of orphan GlyRS is condensed with the largest known spatial rearrangement needed by aaRSs to capture tRNAs, which suggests potential nonactive site targets for aaRS-directed antibiotics, instead of less differentiated hard-to-drug active site locations.

Chemical constituents of industrial hemp roots and their anti-inflammatory activities.

OBJECTIVE: Although the chemical constituents of the aerial parts of Cannabis have been extensively studied, phytochemicals of Cannabis roots are not well characterized. Herein, we investigated the chemical constituents of industrial hemp (Cannabis sativa L.) roots and evaluated the anti-inflammatory activities of phytochemicals isolated from the hemp roots extract. METHODS: An ethyl acetate extract of hemp roots was subjected to a combination of chromatographic columns to isolate phytochemicals. The chemical structures of the isolates were elucidated based on spectroscopic analyses (by nuclear magnetic resonance and mass spectrometry). The anti-inflammatory effects of phytochemicals from hemp roots were evaluated in an anti-inflammasome assay using human monocyte THP-1 cells. RESULTS: Phytochemical investigation of hemp roots extract led to the identification of 32 structurally diverse compounds including six cannabinoids (1-6), three phytosterols (26-28), four triterpenoids (22-25), five lignans (17-21), and 10 hydroxyl contained compounds (7-16), three fatty acids (29-31), and an unsaturated chain hydrocarbon (32). Compounds 14-21, 23, 27, and 32 were identified from the Cannabis species for the first time. Cannabinoids (1-5) reduced the level of cytokine tumor necrosis-alpha (by 38.2, 58.4, 47.7, 52.2, and 56.1%, respectively) and 2 and 5 also decreased the interleukin-1ß production (by 42.2 and 92.4%, respectively) in a cell-based inflammasome model. In addition, non-cannabinoids including 11, 13, 20, 25, 29, and 32 also showed selective inhibition of interleukin-1ß production (by 23.7, 22.5, 25.6, 78.0, 24.1, 46.6, and 25.4%, respectively) in THP-1 cells. CONCLUSION: The phytochemical constituent of a hemp roots extract was characterized and compounds from hemp roots exerted promising anti-inflammatory effects.

Discovery of Spiro[pyrrolidine-3,3'-oxindole] LXRß Agonists for the Treatment of Osteoporosis.

Osteoclasts have an additional demand for cholesterol compared to normal cells. Liver X receptors (LXRs) are famous for regulation of lipid and cholesterol metabolism. Therefore, we propose that the LXR ß agonist can regulate the cholesterol balance in osteoclasts to inhibit osteoclast differentiation. Here, we designed and synthesized a novel LXRß agonist by introduction of the privileged fragments from anti-osteoporosis agents to the spiro[pyrrolidine-3,3'-oxindole] scaffold which is a novel scaffold of LXR agonists in our previous research. As a result, seven LXRß agonists inhibited osteoclastogenesis with IC50 values ranging from 0.078 to 0.36 µM. Especially, the most potent LXRß agonist B9 significantly inhibited RANKL-induced osteoclast differentiation and bone resorption in vitro and in vivo. Furthermore, B9 selectively activated LXRß to promote intracellular cholesterol exclusion in osteoclasts and reduce extracellular cholesterol uptake and thereby inhibited osteoclast production. This study provides a new strategy to develop LXRß agonists for osteoporosis.

Punicesterones A-G, polyhydroxylated mycoecdysteroids from the deep-sea-derived fungus Aspergillus puniceus SCSIO z021.

Seven undescribed polyhydroxylated mycoecdysteroids, punicesterones A-G, along with two known analogues, were isolated from the deep-sea-derived fungal strain Aspergillus puniceus SCSIO z021 (Trichocomaceae). Their structures with absolute configurations were elucidated by a combination of extensive NMR spectroscopic analysis, HRESIMS data, and single-crystal X-ray diffraction experiments. Punicesterone An unexpectedly possessed a nicotinoyl unit substituted at C-22 of a typical ecdysteroid skeleton. All of the isolated compounds were evaluated for their anti-inflammatory, lipid-lowering, and antibacterial activities. Punicesterones B and C showed the activity of reducing triglyceride in 3T3-L1 adipocytes in a dosage-dependent manner, and also exhibited antibacterial activity against five pathogens.