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Results for “molecular docking studies”

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PubMed2005

Synthesis and identification of [1,3,5]triazine-pyridine biheteroaryl as a novel series of potent cyclin-dependent kinase inhibitors.

On the basis of previous studies, we identified pyrazine-pyridine A as a potent vascular endothelial growth factor inhibitor and pyrimidine-pyridine B as a moderately potent cyclin dependent kinase (CDK) inhibitor. A proposed combination of CGP-60474 and compound B led to the discovery of [1,3,5]triazine-pyridine as a new series of potent CDK inhibitors. Palladium-catalyzed C-C bond formation reactions, particularly the Negishi coupling reaction, were used to assemble various triazine-heteroaryl analogues effectively. Among them, compound 20 displayed high inhibitory potency at CDK1 (IC(50) = 0.021 microM), CDK2, and CDK5 and submicromolar potency at CDK4, CDK6, and CDK7. Compound 20 also displayed high potency at GSK-3beta. It demonstrated potent antiproliferative activity on various tumor cell lines, including HeLa, HCT-116, U937, and A375. When 20 was administered intraperitoneally at 150 and 125 mg/kg to nude mice bearing human A375 xenografts, the compound produced a significant survival increase. Molecular docking studies were conducted in an attempt to enhance the understanding of the observed structure-activity relationship.

Aminopyridines↗

PubMed1995

Hydration of nucleic acid fragments: comparison of theory and experiment for high-resolution crystal structures of RNA, DNA, and DNA-drug complexes.

A computationally efficient method to describe the organization of water around solvated biomolecules is presented. It is based on a statistical mechanical expression for the water-density distribution in terms of particle correlation functions. The method is applied to analyze the hydration of small nucleic acid molecules in the crystal environment, for which high-resolution x-ray crystal structures have been reported. Results for RNA [r(ApU).r(ApU)] and DNA [d(CpG).d(CpG) in Z form and with parallel strand orientation] and for DNA-drug complexes [d(CpG).d(CpG) with the drug proflavine intercalated] are described. A detailed comparison of theoretical and experimental data shows positional agreement for the experimentally observed water sites. The presented method can be used for refinement of the water structure in x-ray crystallography, hydration analysis of nuclear magnetic resonance structures, and theoretical modeling of biological macromolecules such as molecular docking studies. The speed of the computations allows hydration analyses of molecules of almost arbitrary size (tRNA, protein-nucleic acid complexes, etc.) in the crystal environment and in aqueous solution.

Crystallography, X-Ray↗

PubMed2026

Development of metal-free one-pot sequential synthesis of carbazolyl-thiazolidinones as anti-leukemic agents with potential β-catenin/c-MYC pathway modulation: from synthesis to in vitro and in silico profiling.

Cancer remains a leading cause of mortality worldwide, necessitating the development of new, selective, and potent therapeutic agents. In this study, a novel, metal-free, one-pot sequential synthetic approach was developed for the synthesis of carbazolyl-thiazolidinone (CTZD) derivatives via the reaction of N-octylcarbazole-3-carbaldehyde with variety of aromatic and aliphatic primary and secondary amines and thioglycolic acid. This strategy efficiently yielded a diverse range of CTZD derivatives (4a-p) in moderate to high yields (20-95%). The synthesized compounds were characterized by FTIR, NMR (1H, 13C, DEPT, APT), and HRMS. Their in vitro cytotoxicity was tested on human leukemia cell lines NB4, K562 and U937 using MTT assays, where four derivatives (4e, 4i, 4j, and 4o) exhibited potent, concentration-dependent antiproliferative activity over the tested concentration range (1.25-10 μM). As c-MYC is a key regulator of cell proliferation, qRT-PCR analysis demonstrated that these four derivatives significantly downregulated c-MYC mRNA expression, with compound 4j producing the greatest reduction, suggesting a potential association with modulation of the Wnt/β-catenin pathway. DNA fragmentation analysis showed no detectable late-stage apoptosis, indicating that the observed c-MYC downregulation and antiproliferative effects were not associated with late-stage apoptotic cell death. The ADME/T analysis of all compounds showed favorable pharmacokinetic profiles with prediction of good oral absorption (HIA >92%) and no hERG I liability. Molecular docking studies demonstrated strong binding affinities of these compounds to β-catenin protein (PDB ID: 7ZRB) with compound 4i showing strongest affinity with ΔG = -8.10 kcal/mol via H-bonds with Ser473, Asn430, Arg469 and His470 amino acid residues. The developed metal-free synthesis provided a sustainable route to bioactive carbazolyl-thiazolidinones, and derivatives 4e, 4i, 4j, 4o could be promising leads for targeting Wnt/β-catenin/c-MYC signaling in leukemia.

Humans↗

PubMed2006

Acetylcholinesterase: molecular modeling with the whole toolkit.

Molecular modeling efforts aimed at probing the structure, function and inhibition of the acetylcholinesterase enzyme have abounded in the last decade, largely because of the system's importance to medical conditions such as myasthenia gravis, Alzheimer's disease and Parkinson's disease, and well as its famous toxicological susceptibility to nerve agents. The complexity inherent in such a system with multiple complementary binding sites, critical dynamic effects and intricate mechanisms for enzymatic function and covalent inhibition, has led to an impressively diverse selection of simulation techniques being applied to the system, including quantum chemical mechanistic studies, molecular docking prediction of noncovalent complexes and their associated binding free energies, molecular dynamics conformational analysis and transport kinetics prediction, and quantitative structure activity relationship modeling to tie salient details together into a coherent predictive tool. Effective drug and prophylaxis design strategies for a complex target like this requires some understanding and appreciation for all of the above methods, thus it makes an excellent case study for multi-tiered pharmaceutical modeling. This paper reviews a sample of the more important studies on acetylcholinesterase and helps to elucidate their interdependencies. Potential future directions are introduced based on the special methodological needs of the acetylcholinesterase system and on emerging trends in molecular modeling.

Acetylcholinesterase↗

PubMed2003

Soluble forms of Toll-like receptor (TLR)2 capable of modulating TLR2 signaling are present in human plasma and breast milk.

Dysregulation of the initial, innate immune response to bacterial infection may lead to septic shock and death. Toll-like receptors (TLRs) play a crucial role in this innate immune response, and yet the regulatory mechanisms controlling microbial-induced TLR triggering are still to be fully understood. We have therefore sought specific regulatory mechanisms that may modulate TLR signaling. In this study, we tested for the possible existence of a functionally active soluble form of TLR2. We demonstrated the existence of natural soluble forms of TLR2 (sTLR2), which we show to be capable of modulating cell activation. We found that blood monocytes released sTLR2 constitutively and that the kinetics of sTLR2 release increased upon cell activation. Analysis of cells expressing the human TLR2 cDNA or its c-myc-tagged version indicated that sTLR2 resulted from the posttranslational modification of the TLR2 protein in an intracellular compartment. Moreover, an intracellular pool of sTLR2 is maintained. sTLR2 was found naturally expressed in breast milk and plasma. Milk sTLR2 levels mirrored those of the TLR coreceptor soluble CD14. Depletion of sTLR2 from serum resulted in an increased cellular response to bacterial lipopeptide. Notably, serum sTLR2 was lower in tuberculosis patients. Coimmunoprecipitation experiments and computational molecular docking studies showed an interaction between sTLR2 and soluble CD14 in plasma and milk. These findings suggest the existence of a novel and specific innate immune mechanism regulating microbial-induced TLR triggering, and may lead to new therapeutics for the prevention and/or treatment of severe infectious diseases.

Amino Acid Sequence↗

PubMed2005

6-(N-benzoylamino)purine as a novel and potent inhibitor of xanthine oxidase: inhibition mechanism and molecular modeling studies.

The inhibition of xanthine oxidase (XO) activity by the purine analogue 6-(N-benzoylamino)purine was evaluated and compared with the standard inhibitor, allopurinol and the parent compound adenine. 6-(N-benzoylamino)purine is a highly potent inhibitor of XO (IC50 = 0.45 microM) and comparable to allopurinol (IC50 = 0.80 microM). Furthermore, 6-(N-benzoylamino)purine neither produced any enzymatic superoxide nor reduced XO by an electron transfer reaction unlike allopurinol. 6-(N-benzoylamino)purine (Ki = 0.0475 microM) is about 10000-fold more potent as a XO inhibitor compared to the only known purine analogue 8-bromoxanthine (Ki = 400 microM). 6-(N-Benzoylamino)purine is a competitive inhibitor of XO and the inhibition was not completely reversed even at 100 microM xanthine concentration. The calculated interaction energy [Ecomplex - (Eligand + Eprotein)] of -30.5, -22.6, and -17.2 kcal/mol, respectively, of 6-(N-benzoylamino)purine, 8-bromoxanthine and the parent compound adenine provided the rationale for the better enzyme inhibitory activity of 6-(N-benzoylamino)purine. To understand the role of the benzamido group in the inhibition process, molecular docking studies were carried out and it was revealed that the hydrogen bonding interactions involving N-7 of the purine ring and the N-H of Arg880, N-H of the purine ring and OH of Thr1010, as well as non-bonded interactions of the benzamido group of 6-(N-benzoylamino)purine with amino acid residues Gly799, Glu802, Phe914, Ala1078, Ala1079 and Glu1261 in the active site of XO play an important role in the stabilization of the E-I complex.

Adenine↗

PubMed2004

Further insights on the structural aspects of PLA(2) inhibition by gamma-hydroxybutenolide-containing natural products: a comparative study on petrosaspongiolides M-R.

Petrosaspongiolides M-R (PM-PR, 1-5) are marine sesterterpenes structurally characterised by a gamma-hydroxybutenolide moiety. They have shown an in vitro and in vivo potent anti-inflammatory activity, mediated by specific inhibition of secretory phospholipase A(2) (sPLA(2) enzymes). The molecular mechanism underlying the sub-micromolar irreversible inhibition of the bee-venom PLA(2) (bvPLA(2)) by PM has been clarified combining mass spectrometry (MS) and molecular modelling approaches. The N-terminal amino group (Ile-1 residue), recently identified as the unique PM covalent binding site on this enzyme, selectively delivers a nucleophilic attack onto the masked aldehyde at C-25 of the pharmacophoric gamma-hydroxybutenolide ring of PM, giving rise to a Schiff base. In the attempt of broadening the knowledge of the mechanism at molecular level of PLA(2) inactivation by this family of compounds, we performed a comparative analysis on petrosaspongiolides M-R, whose results are discussed in this paper. Firstly, the amount of bvPLA(2) enzyme covalently modified after incubation with each of petrosaspongiolides M-R was measured and resulted to be in good agreement with pharmacological in vitro data. Then, a full characterisation of the bvPLA(2) adduct with PR, one of the least active and most structurally different among petrosaspongiolides, by LC-MS, MS(n), and computational methods, confirmed the same inhibition mechanism and covalent binding site already found for PM. Finally, extensive molecular docking studies performed in comparison on the PM-PLA(2) and PR-PLA(2) complexes provided critical insight on how the balance between non-covalent and covalent inhibitor-enzyme interactions may affect the final potency exhibited by the various compounds of the petrosaspongiolide family.

4-Butyrolactone↗

PubMed1994

The monosaccharide binding site of lentil lectin: an X-ray and molecular modelling study.

The X-ray crystal structure of lentil lectin in complex with alpha-D-glucopyranose has been determined by molecular replacement and refined to an R-value of 0.20 at 3.0 A resolution. The glucose interacts with the protein in a manner similar to that found in the mannose complexes of concanavalin A, pea lectin and isolectin I from Lathyrus ochrus. The complex is stabilized by a network of hydrogen bonds involving the carbohydrate oxygens O6, O4, O3 and O5. In addition, the alpha-D-glucopyranose residue makes van der Waals contacts with the protein, involving the phenyl ring of Phe123 beta. The overall structure of lentil lectin, at this resolution, does not differ significantly from the highly refined structures of the uncomplexed lectin. Molecular docking studies were performed with mannose and its 2-O and 3-O-m-nitro-benzyl derivatives to explain their high affinity binding. The interactions of the modelled mannose with lentil lectin agree well with those observed experimentally for the protein-carbohydrate complex. The highly flexible Me-2-O-(m-nitro-benzyl)-alpha-D-mannopyranoside and Me-3-O-(m-nitro-benzyl)-alpha-D-mannopyranoside become conformationally restricted upon binding to lentil lectin. For best orientations of the two substrates in the combining site, the loss of entropy is accompanied by the formation of a strong hydrogen bond between the nitro group and one amino acid, Gly97 beta and Asn125 beta, respectively, along with the establishment of van der Waals interactions between the benzyl group and the aromatic amino acids Tyr100 beta and Trp128 beta.

Binding Sites↗

PubMed2005

Evolutionary trace analysis of eukaryotic DNA topoisomerase I superfamily: identification of novel antitumor drug binding site.

The studies of novel inhibitors of DNA topoisomerase I (Topo I) have already become very promising in cancer chemotherapy. Identifying the new drug-binding residues is playing an important role in the design and optimization of Topo I inhibitors. The designed compounds may have novel scaffolds, thus will be helpful to overcome the toxicities of current camptothecin (CPT) drugs and may provide a solution to cross resistance with these drugs. Multiple sequence alignments were performed on eukaryotic DNA topoisomerase I superfamily and thus the evolutionary tree was constructed. The Evolutionary Trace method was applied to identify functionally important residues of human Topo I. It has been demonstrated that class-specific hydrophobic residues Ala351, Met428, Pro431 are located around the 7,9-position of CPT, indicating suitable substitution of hydrophobic group on CPT will increase antitumor activity. The conservative residue Lys436 in the superfamily is of particular interest and new CPT derivatives designed based on this residue may greatly increase water solubility of such drugs. It has also been demonstrated that the residues Asn352 and Arg364 were conservative in the superfamily, whose mutation will render CPT resistance. As our molecular docking studies demonstrated they did not make any direct interaction with CPT, they are important drug-binding site residues for future design of novel non-camptothecin lead compounds. This work provided a strong basis for the design and synthesis of novel highly potent CPT derivatives and virtual screening for novel lead compounds.

Amino Acid Sequence↗

PubMed2002

Interaction of designed sulfated flavanoids with antithrombin: lessons on the design of organic activators.

Recently, we designed (-)-epicatechin sulfate (ECS), the first small nonsaccharide molecule, as an activator of antithrombin for the accelerated inhibition of factor Xa, a key proteinase of the coagulation cascade (Gunnarsson, G. T.; Desai, U. R. J. Med. Chem. 2002, 45, 1233-1243). Although sulfated flavanoid ECS was found to bind antithrombin with an affinity ( approximately 10.7 microM) comparable to the reference trisaccharide DEF ( approximately 4.5 microM), it accelerated the inhibition of factor Xa only 10-fold as compared to the approximately 300-fold observed with DEF. To determine whether this conformational activation of the inhibitor is dependent on the structure of the organic activator and to probe the basis for the deficiency in activation, we studied the interaction of similar sulfated flavanoids with antithrombin. (+)-Catechin sulfate (CS), a chiral stereoisomer of ECS, bound plasma antithrombin with a 3-fold higher affinity (K(D) = 3.5 microM) and a 2-fold higher second-order rate constant for factor Xa inhibition (k(ACT) = 6750 M(-1) s(-1)). On the contrary, the K(D) and k(ACT) were found to be lower approximately 7.4- and approximately 2.4-fold, respectively, for its racemic counterpart, (+/-)-catechin sulfate. Dependence of the equilibrium dissociation constant on the ionic strength of the medium at pH 6.0 and 7.4 suggests that nonionic interactions contribute a major proportion ( approximately 55-73%) of the total binding energy, and only 1-2 ion pairs, in comparison to the expected approximately 4 ion pairs for the reference trisaccharide, are formed in the interaction. Competitive binding experiments indicate that activator CS does not compete with a saccharide ligand that binds antithrombin in the pentasaccharide binding site, while it competes with full-length low-affinity heparin. A molecular docking study suggests plausible binding of CS in the extended heparin binding site, which is adjacent to the binding domain for the reference trisaccharide DEF. In combination, the results demonstrate that although conformational activation of antithrombin with small sulfated flavanoids is dependent on the structure of the activator, the designed activators do not bind in the pentasaccharide binding site in antithrombin resulting in weak activation. The mechanistic investigation highlights plausible directions to take in the rational design of specific high-affinity organic antithrombin activators.

Antithrombins↗

PubMed2004

Synthesis and evaluation of S-4-(3-thienyl)phenyl-alpha-methylacetic acid.

Herein we report an efficient procedure to synthesize S-4-(3-thienyl)phenyl-alpha-methylacetic acid, an enantiomerically pure intermediate of a recently approved nonsteroidal antiinflammatory cyclooxygenase inhibitor, atliprofen [methyl RS-4-(3-thienyl)phenyl-alpha-methylacetate]. The interactions of the active S-isomer of the acid were theoretically compared with those of S-ibuprofen through molecular docking studies using COX-1 and COX-2 protein structures. The results were corroborated by in vitro and in vivo studies.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed2005

Synthesis and discovery of pyrazine-pyridine biheteroaryl as a novel series of potent vascular endothelial growth factor receptor-2 inhibitors.

Pathological angiogenesis is associated with disease states such as cancer, diabetic retinopathy, rheumatoid arthritis, endometriosis, and psoriasis. There is much evidence that direct inhibition of the kinase activity of vascular endothelial growth factor receptor-2 (VEGFR-2) will result in the reduction of angiogenesis and the suppression of tumor growth. Attempts to optimize a cyclin-dependent kinase-1 (CDK1) inhibitor by using palladium-catalyzed C-C bond, C-N bond formation reactions to assemble diverse biheteroaryl molecules led to the unexpected discovery of a pyrazine-pyridine biheteroaryl as a novel series of potent VEGFR-2 inhibitors. Compound 15, which had IC(50) = 0.084 microM at VEGFR-2, showed very modest selectivity against fibroblast growth factor receptor-2 (IC(50) = 0.21 microM), platelet-derived growth factor receptor (IC(50) = 0.36 microM), and glycogen synthase kinase-3 (IC(50) = 0.478 microM), while it exhibited more than 10-fold selectivity against epidermal growth factor receptor (IC(50) = 1.36 microM) and insulin-R kinase (IC(50) = 1.69 microM). On the other hand, compound 15 exhibited more than 100-fold selectivity against calmodulin kinase 2; casein kinase-1 and -2; CDK1 and -4; mitogen-activated protein kinase; and protein kinase A, Cbeta2, and Cgamma (IC(50) >10 microM). Compound 15 also displayed high inhibitory potency on VEGF-stimulated human umbilical vein endothelial cell (HUVEC) proliferation (IC(50) = 0.005 microM) and good selectivity against cell lines such as HUVEC, human aortic smooth muscle cells, and MRC5 lung fibroblasts. Molecular docking studies were conducted in an attempt to rationalize the unexpected high VEGFR-2 selectivity of 15.

Angiogenesis Inhibitors↗

PubMed2003

Mechanism of the glutathione transferase-catalyzed conversion of antitumor 2-crotonyloxymethyl-2-cycloalkenones to GSH adducts.

Human glutathione (GSH) transferase (hGSTP1-1) processes with similar kinetic efficiencies the antitumor agents 2-crotonyloxymethyl-2-cyclohexenone (COMC-6), 2-crotonyloxymethyl-2-cycloheptenone (COMC-7), and 2-crotonyloxymethyl-2-cyclopentenone (COMC-5) to 2-glutathionylmethyl-2-cyclohexenone, 2-glutathionylmethyl-3-glutathionyl-2-cycloheptenone, and 2-glutathionylmethyl-2-cyclopentenone, respectively. This process likely involves initial enzyme-catalyzed Michael addition of GSH to the COMC derivative to give a glutathionylated enol(ate), which undergoes nonstereospecific ketonization, either while bound to the active site or free in solution, to a glutathionylated exocyclic enone. Free in solution, GSH reacts at the exomethylene carbon of the exocyclic enone, displacing the first GSH to give the final product. This mechanism is supported by the observation of multiphasic kinetics in the presence of high concentrations of hGSTP1-1 and the ability to trap kinetically competent exocyclic enones in aqueous acid using COMC-6 and COMC-7 as substrates. That the exocyclic enone is formed by nonstereospecific ketonization of an enol(ate) species is indicated by the observation that COMC-6 (chirally labeled with deuterium at the exomethylene carbon) gives stereorandomly labeled exocyclic enone. The isozymes hGSTP1-1, hGSTA1-1, hGSTA4-4, and hGSTM2-2 catalyze the conversion of COMC-6 to final product with similar efficiencies (K(m) = 0.08-0.34 mM, k(cat) = 1.5-6.1 s(-)(1)); no activity was detected with the rat rGSTT2-2 isozyme. Molecular docking studies indicate that in hGSTP1-1, the hydroxyl group of Tyr108 might serve as a general acid catalyst during substrate turnover. The possible significance of these observations with respect to the metabolism of COMC derivatives in multidrug resistant tumors is discussed.

Antineoplastic Agents↗

PubMed2004

Conformationally constrained analogues of diacylglycerol (DAG). 23. Hydrophobic ligand-protein interactions versus ligand-lipid interactions of DAG-lactones with protein kinase C (PK-C).

The constrained glycerol backbone of DAG-lactones, when combined with highly branched alkyl chains, has engendered a series of DAG-lactone ligands capable of binding protein kinase C (PK-C) with affinities that approximate those of phorbol esters. These branched chains not only appear to be involved in making important hydrophobic contacts with the protein (specific interactions) but also provide adequate lipophilicity to facilitate partitioning into the lipid-rich membrane environment (nonspecific interactions). With the idea of minimizing the nonspecific interactions without reducing lipophilicity, the present work explores the strategy of relocating lipophilicity from the side chain to the lactone "core". Such a transfer of lipophilicity, exemplified by compounds 1 and 3, was conceived to allow the new hydrophobic groups on the lactone to engage in specific hydrophobic contacts inside the binding pocket without any expectation of interfering with the hydrogen-bonding network of the DAG-lactone pharmacophore. Surprisingly, both (E)-3 and (Z)-3 showed a significant decrease in binding affinity. From the molecular docking studies performed with the new ligands, we conclude that the binding pocket of the C1 domain of PK-C is sterically restricted and prevents the methyl groups at the C-3 position of the lactone from engaging in productive hydrophobic contacts with the receptor.

Binding Sites↗

PubMed2004

2-difluoromethyloestrone 3-O-sulphamate, a highly potent steroid sulphatase inhibitor.

Steroid sulphatase is a target enzyme of growing therapeutic importance. The synthesis and in vitro biological evaluation of three novel 2-substituted analogues of oestrone 3-O-sulphamate (EMATE), an established steroid sulphatase inhibitor, are described. One inhibitor, 2-difluoromethyloestrone 3-O-sulphamate (6), was found to have an IC50 of 100 pM and be some 90-fold more potent than EMATE in inhibiting steroid sulphatase activity in a placental microsomal preparation, rendering this agent the most potent steroidal STS inhibitor in vitro reported to date. Lowering of the pKa value of the leaving parent steroid phenol by the 2-difluoromethyl group during irreversible enzyme sulphamoylation most likely facilitates the potent inactivation of steroid sulphatase by (6). However, our preliminary molecular docking studies using the X-ray crystal structure of steroid sulphatase suggest that F.......H interactions between the 2-difluoromethyl group of (6) and hydrogen bond donor residues lining the catalytic site of STS might also contribute to the high potency observed for (6).

Binding Sites↗

PubMed2005

The furoxan system: design of selective nitric oxide (NO) donor inhibitors of COX-2 endowed with anti-aggregatory and vasodilating activities.

Several NO donor 3,4-diphenylfuroxan (= 3,4-diphenyl-1,2,5-oxadiazole 2-oxide) derivatives were synthesized and tested for their COX-inhibiting activities. The products were found to be selective COX-2 inhibitors, similar to the structurally related furazans (3,4-diphenyl-1,2,5-oxadiazole), devoid of the NO release property. This behavior was confirmed by a molecular-docking study. The NO-dependent platelet anti-aggregatory and vasodilating activities of the new furoxans 5-7 were studied in vitro. These properties can be modulated by inserting an appropriate spacer between the 4-phenyl group and the furoxan ring, giving rise to new, selective COX-2 furoxan derivatives endowed with anti-aggregatory and vasodilating activities, and with potentially reduced cardiotoxicities.

Celecoxib↗

PubMed2006

Structural basis of cell surface receptor recognition by botulinum neurotoxin B.

Botulinum neurotoxins (BoNTs) are potent bacterial toxins that cause paralysis at femtomolar concentrations by blocking neurotransmitter release. A 'double receptor' model has been proposed in which BoNTs recognize nerve terminals via interactions with both gangliosides and protein receptors that mediate their entry. Of seven BoNTs (subtypes A-G), the putative receptors for BoNT/A, BoNT/B and BoNT/G have been identified, but the molecular details that govern recognition remain undefined. Here we report the crystal structure of full-length BoNT/B in complex with the synaptotagmin II (Syt-II) recognition domain at 2.6 A resolution. The structure of the complex reveals that Syt-II forms a short helix that binds to a hydrophobic groove within the binding domain of BoNT/B. In addition, mutagenesis of amino acid residues within this interface on Syt-II affects binding of BoNT/B. Structural and sequence analysis reveals that this hydrophobic groove is conserved in the BoNT/G and BoNT/B subtypes, but varies in other clostridial neurotoxins. Furthermore, molecular docking studies using the ganglioside G(T1b) indicate that its binding site is more extensive than previously proposed and might form contacts with both BoNT/B and synaptotagmin. The results provide structural insights into how BoNTs recognize protein receptors and reveal a promising target for blocking toxin-receptor recognition.

Animals↗

PubMed2026

Targeting pancreatic cancer progression: The formononetin and salvianolic acid B combination suppresses JAK/STAT signaling via MBOAT2 downregulation.

OBJECTIVE: Formononetin and salvianolic acid B (FcS) are the primary bioactive components of the Astragalus mongholicus-Salvia miltiorrhiza herbal pair, a classic combination for treating pancreatic cancer associated with qi deficiency and blood stasis. This study elucidates the therapeutic potential and mechanisms of FcS in the treatment of pancreatic cancer. METHODS: A zebrafish xenograft model was used to screen bioactive combinations derived from A. mongholicus and S. miltiorrhiza, identifying FcS as a candidate with antitumor activity. Its efficacy was evaluated in vivo using the zebrafish model, orthotopic LSL-KrasG12D/+, LSL-Trp53R172H/+ and Pdx-1-Cre (KPC) mice, and subcutaneous xenograft models. Cell viability and proliferation were assessed using cell counting kit-8, 5-ethynyl-2'-deoxyuridine and colony formation assays, and migration and invasion were evaluated by wound healing and transwell assays. Membrane-bound O-acyltransferase 2 (MBOAT2) was identified as a potential target through a molecular docking study and the Cancer Genome Atlas (TCGA) analysis. MBOAT2 knockdown cells were used to explore its roles and the Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway in FcS-mediated inhibition. RESULTS: In the zebrafish model, FcS strongly inhibited pancreatic tumor growth. FcS reduced tumor volume, the expression of proliferation marker Ki-67, and proliferating cell nuclear antigen in KPC mice. In vitro, FcS inhibited pancreatic cancer cell viability, proliferation, migration and invasion, which was accompanied by downregulation of MBOAT2 expression. TCGA analysis linked high MBOAT2 expression to aggressive phenotypes. MBOAT2 knockdown reduced the survival, proliferation and invasion of BxPC-3 cells. Rescue experiments revealed that MBOAT2 knockdown attenuated the antitumor effects of FcS, possibly through modulation of the JAK/STAT signaling pathway. FcS also inhibited tumor proliferation in xenograft models, and MBOAT2 expression was elevated in tumor tissues from pancreatic cancer patients. CONCLUSION: FcS suppresses pancreatic cancer progression via MBOAT2 downregulation and JAK/STAT pathway inhibition, which highlights MBOAT2 as a potential therapeutic target. Please cite this article as: Xu Y, Xu CS, Jin HB, Gu WG, Shen HZ, Lu L, Chen Y, Xu DC, Zhang XF, Yang JF, Wang Y. Targeting pancreatic cancer progression: The formononetin and salvianolic acid B combination suppresses JAK/STAT signaling via MBOAT2 downregulation. J Integr Med. 2026; 24(5):725-741.

Animals↗