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The pharmacological inhibition of IDO1 is considered an effective therapeutic approach for cancer treatment. However, the inadequate response of existing holo-IDO1 inhibitors and unclear biomarkers available in clinical practice limit the possibility of developing efficacious IDO1 inhibitors. In the current study, we aimed to elucidate the activity and mechanism of a potent 1H-pyrrole-2-carboxylic acid derivative (B37) targeting apo-IDO1 and to determine its role in tumor therapy. By competing with heme for binding to apo-IDO1, B37 potently inhibited IDO1 activity, with an IC50 of 22 pM assessed using a HeLa cell–based assay. The x-ray cocrystal structure of the inhibitor–enzyme complex showed that the B37–human IDO1 complex has strong hydrophobic interactions, which enhances its binding affinity, determined using isothermal titration calorimetry. Stronger noncovalent interactions, including π stacking and hydrogen bonds formed between B37 and apo-human IDO1, underlay the enthalpy-driven force for B37 for binding to the enzyme. These binding properties endowed B37 with potent antitumor efficacy, which was confirmed in a mouse colon cancer CT26 syngeneic model in BALB/c mice and in an azoxymethane/dextran sulfate sodium–induced colon carcinogenesis model in C57BL/6 mice by activating the host immune system. Moreover, the combination of B37 and anti-PD1 Ab synergistically inhibited tumor growth. These results suggested that B37 may serve as a unique candidate for apo-IDO1 inhibition-mediated tumor immunotherapy.

Liu, W., Y. Zou, K. Li, H. Zhong, L. Yu, S. Ge, Y. Lai, X. Dong, Q. Xu, and W. Guo. 2022. Apo-form selective inhibition of IDO for tumor immunotherapy. J. Immunol. 209: 180–191. Supplemental Table I did not originally contain the Protein Data Bank (PDB) code for the x-ray crystal structure analyzed in the article. The coordinates of PDB ID 8I7L were released after publication on February 15, 2023. Supplemental Table I has been corrected online. As this structure is marginally different from the one originally analyzed in the article, the first paragraph of the Results section headed “Distinct bonding networks from those of BMS-986205 contributed to the potency of B37” was amended to reflect the updated resolution limit and root-mean-square deviation of this structure. The corrected paragraph is shown below. Having identified B37 as a compound with a superior biochemical profile, we crystallized the hIDO1–B37 complex and refined its structure to a resolution of 2.80 Å (Fig. 3A, Supplemental Table I) to understand the structural basis of binding. Strong electron density associated with B37 and adjacent water molecules was evident in the binding pocket. B37 binding did not significantly alter the overall structure of IDO1 (root-mean-square deviation of 0.671) compared to holo-IDO1 (PDB code: 6AZU) (17). The major structural rearrangement introduced by B37 binding was a shift in the region between G261 and Q271, an event previously observed as a result of binding of the substrate tryptophan or its analogs (29, 30). In particular, the heme-coordinating residue A264 was the most significantly perturbed (root-mean-square deviation measured at Cα = 3.6) upon B37 binding. B37 and heme shared a cavity similar to that of BMS-978587 and BMS-986205 inside IDO1 (Fig. 3B–I), confirming the hypothesis that B37 is a heme-competitive IDO1 inhibitor. Unlike the nearly planar heme molecule, B37 and its halogenated phenyl moiety extend deeply into the “A” pocket located in the distal heme site (7, 11). The corrections have been made in the online version of the article, which now differs from the print version as originally published.

KRAS

Colorectal cancer (CRC) is the third most common cancer in the world. Recently, many clinical studies have demonstrated the therapeutic potential of immune checkpoint therapy combined with inhibitors of vascular endothelial growth factor receptor 2 (VEGFR2) in colon cancer. Compound B37, identified in our previous experiment, is an apo-form indoleamine-2,3-dioxygenase 1 inhibitor (apo-IDO1 inhibitor), which has been shown to significantly suppress tumor growth combined with an anti-PD1 antibody. We speculated whether this apo-IDO inhibitor (B37) combined with a VEGFR2 inhibitor (apatinib) would further improve its anti-tumor activity. Therefore, a syngeneic mouse colon cancer model (mouse colon cancer cell line CT26) was established to investigate the anti-tumor activity of B37 combined with apatinib. As expected, the combination of B37 and apatinib (VEGFR2 inhibitor) improved the therapeutic effect compared with apo-IDO1 inhibitor and apatinib monotherapy, as shown by the reduced growth of transplanted tumors, weakened proliferation, and increased apoptosis of cancer cells. Specifically, there was a 24.8% reduction in tumor volume using apatinib and 31.3% reduction using B37. The combination-treated group showed remarkable inhibition of tumor growth (52.2%). For tumor weight, there was a 29.2% reduction in the apatinib-treated group and 35.0% reduction in the B37-treated group. The combination-treated group showed a 56.3% reduction. Moreover, the combination therapy reprogrammed the immune microenvironment by increasing infiltration of CD4

Two series of novel o-(biphenyl-3-ylmethoxy)nitrophenyl compounds (A1-31 and B1-17) were designed as programmed cell death protein 1 (PD-1)/PD-ligand 1 (PD-L1) inhibitors. All compounds showed significant inhibitory activity with IC50 values ranging from 2.7 to 87.4 nM except compound A17, and compound B2 displayed the best activity. Further experiments showed that B2 bound to the PD-L1 protein without obvious toxicity in Lewis lung carcinoma (LLC) cells. Furthermore, B2 significantly promoted interferon-gamma secretion in a dose-dependent manner in vitro and in vivo. Especially, B2 exhibited potent in vivo anticancer efficacy in an LLC-bearing allograft mouse model at a low dose of 5 mg/kg, which was more active than BMS-1018 (tumor growth inhibition rate: 48.5% vs 17.8%). A panel of immunohistochemistry and flow cytometry assays demonstrated that B2 effectively counteracted PD-1-induced immunosuppression in the tumor microenvironment, thereby triggering antitumor immunity. These results indicate that B2 is a promising PD-1/PD-L1 inhibitor worthy of further development.

Indoleamine 2,3-dioxygenase 1 (IDO1) as a key rate-limiting enzyme in the kynurenine pathway of tryptophan metabolism plays an important role in tumour immune escape. Herein, a variety of secondary sulphonamides were synthesised and evaluated in the HeLa cell-based IDO1/kynurenine assay, leading to the identification of new IDO1 inhibitors. Among them, compounds 5d, 5l and 8g exhibited the strongest inhibitory effect with significantly improved activity over the hit compound BS-1. The in vitro results showed that these compounds could restore the T cell proliferation and inhibit the differentiation of naïve CD4+ T cell into highly immunosuppressive FoxP3+ regulatory T (Treg) cell without affecting the viability of HeLa cells and the expression of IDO1 protein. Importantly, the pharmacodynamic assay showed that compound 5d possessed potent antitumour effect in both CT26 and B16F1 tumours bearing immunocompetent mice but not in immunodeficient mice. Functionally, subsequent experiments demonstrated that compound 5d could effectively inhibit tumour cell proliferation, induce apoptosis, up-regulate the expression of IFN-γ and granzyme B, and suppress FoxP3+ Treg cell differentiation, thereby activate the immune system. Thus, compound 5d could be a potential and efficacious agent for further evaluation.

Two series of novel

It was proven by Cox, Goldman and Zhang that a tensor product rational surface without base points can be implicitized by moving quadrics whenever the rational surface doesn't contain low degree moving planes following it. However, when the rational surface does have low degree moving planes, Cox, Goldman and Zhang's method fails. In this paper, we show that a rational surface without base points can always be implicitized by moving quadrics together with moving planes whether the rational surface has low degree moving planes or not. A specific method is also provided to construct the moving planes and moving quadrics that comprise a compact determinantal representation of the implicit equation of the rational surface.

This paper provides an elementary and constructive treatment to implicitizing tensor product rational surfaces whose base point locus is a local complete intersection (lci) by the method of moving planes and moving quadrics. The approach is much more elementary than that by Buse and Chen (2021) which relies on very advanced algebraic tools such as Rees algebras and symmetric algebras, etc. An effective algorithm is also presented to compute moving planes and moving quadrics that comprise a compact determinantal representation of the implicit equation of a rational surface.

BACKGROUND AND PURPOSE Pharmacological inhibition of indoleamine-2,3-dioxygenase 1 activity is now considered to be a potential therapeutic tool for cancer therapy. However, the anti-cancer efficacy may be the biggest obstacle for the clinical application of current IDO1 inhibitors. EXPERIMENTAL APPROACHES HeLa cell-based IDO1/Kyn assay as well as recombinant IDO1 activity assay were used to determine the IDO1 enzyme activity. Interaction was examined by UV-visible spectra, isothermal titration calorimetry assay, cellular thermal shift assay and co-crystallization. Mouse colon cancer CT26 syngeneic model and azoxymethane/dextran sulfate sodium induced colon carcinogenesis model were employed to confirm the anti-tumor effect in vivo. KEY RESULTS B37 effectively and specifically inhibited IDO1 by targeting its heme-free conformation (apo-IDO1). By competing with heme for binding to apo-IDO1, B37 potently inhibited IDO1 activity with IC50 for 22 pM in the HeLa cell based assay. X-ray co-crystal structures of the inhibitor-enzyme complexes showed that unlike the hIDO1-BMS-986205 complex, the B37-hIDO1 complex displayed stronger hydrophobic interactions, which enhanced its binding affinity measured with ITC. Accordingly, stronger non-covalent interactions including π stacking and hydrogen bonds formed between B37 and apo-hIDO1 underlay the enthalpy-driven force for B37 to bind the enzyme. This binding model endowed B37 potent anti-tumor efficacy in mouse colon cancer CT26 syngeneic model and azoxymethane/dextran sulfate sodium induced colon carcinogenesis model by activating the host’s immune system. Moreover, the combination of B37 with a VEGFR2 inhibitor apatinib synergistically inhibited tumor growth. CONCLUSIONS AND IMPLICATIONS These results revealed that B37 may serve as a candidate for apo-IDO1 inhibition mediated immunotherapy.

ONTD (3-Oxo-29-noroleana-1,9(11),12-trien-2,20-dicarbonitrile) is a novel synthetic derivative of glycyrrhetinic acid (GA), which has been reported to exhibit anti-inflammatory and anti-tumor activities through its mechanisms are not fully understood. Previously, we demonstrated that ONTD induces apoptosis of human hepatoma cells via a MAPK-dependent mitochondrial pathway. Recently, ONTD was found to increase sub-G1 accumulation and Annexin-V positive staining, indicating apoptotic induction effect. It was also be found that ONTD increase the PPAR-γ activity, reduce the phosphorylation of Akt and increase phosphatase and tensin homologue (PTEN) protein expression in hepatocellular carcinoma (HCC) Bel-7402 cells, and these were associated with the inhibition of cells proliferation. More importantly, these effects could be diminished by GW9662, a specific PPAR-γ antagonist, suggesting that ONTD can act as a ligand of PPAR-γ. Taken together, our novel observations suggested that ONTD may have potential implication in HCC prevention and treatment, and showed for the first time that the anti-tumor effect of ONTD may also be mediated through modulation of the PPAR-γ activation and mediated by the PTEN/Akt signaling pathway. The present study also supports ONTD as a potential drug candidate for chemoprevention or chemotherapy of HCC.

Indoleamine-2,3-dioxygenase-1 (IDO1) is an attractive target for cancer immunotherapy. Herein, a series of novel imidazoleisoindole derivatives were prepared and evaluated for their ability to inhibit IDO1. Among these, derivative 11r was the most active compound with nanomolar potency in the Hela cell-based assay, while showed negligible cellular toxicity. UV-visible spectra study demonstrated that compounds 11p and 11r bound to IDO1 and coordinated with the heme iron. Furthermore, they could significantly promote T cell proliferation, increase IFN-γ production, and reduce the numbers of Foxp3+ regulatory T cells. Finally, induced fit docking (IFD) and quantum mechanics/molecular mechanics (QM/MM) calculation were performed to understand the interactions of these compounds to IDO1 protein, which provided a comprehensive guide for further structural modification and optimization.

Diaryl formation is achieved by coupling phenols and (hetero)aryl halides under the catalysis of CuI/N,N'-bis(2-phenylphenyl) oxalamide (BPPO) or CuI/N-(2-phenylphenyl)-N'-benzyl oxalamide (PPBO) at 90 °C using DMF or MeCN as the solvent. Only 0.2-2 mol % CuI and ligand are required for complete conversion, which represents the lowest catalytic loadings for a general Cu/ligand-catalyzed diaryl ether formation.

A Re 2 O 7 catalyzed cycloetherification of monoallylic diols is described. The reaction features short reaction time, mild reaction conditions and exclusive E selectivity. A wide range of monoallylic alcohols with alkyl or aryl substituents on olefin smoothly undergo ring closure to deliver corresponding oxa-heterocycles. The reaction is also operationally simple and not sensitive to air and moisture.

A group of photochemical nitric oxide (NO) delivery agents, O2-(4-hydroxyphenacyl) diazeniumdiolates 1–2 as well as O2-(3-(benzothiazole-2-yl)-4-hydroxyphenacyl) diazeniumdiolates 3–4, could be triggered by ultraviolet light (365–400 nm) and visible light (≥410 nm), respectively, to produce NO in cancer cells and generate potent antitumor activity. Importantly, with the photolysis of 3 being initiated, the accompanying distinct fluorescence color change (from green to blue) may act as a qualitative real-time optical indicator for NO release in cancer cells.

This paper presents a new algorithm for implicitizing tensor product surfaces of bi-degree ( m , n ) with no base points, assuming that there are no moving planes of bi-degree ( m - 1 , n - 1 ) following the surface. The algorithm is based on some structural results: (1) There are exactly 2n linearly independent moving planes of bi-degree ( m , n - 1 ) following the surface; (2) mn linearly independent moving quadrics of bi-degree ( m - 1 , n - 1 ) following the surface can be constructed from the 2n linearly independent moving planes; (3) The mn linearly independent moving quadrics form a compact determinant of order mn which exactly gives the implicit equation of the rational surface. Complexity analysis and experimental results show that the new algorithm is significantly more efficient than the previous methods.

Developing small molecules occupying the heme-binding site using computational approaches remains a challenging task because it is difficult to characterize heme-ligand interaction in heme-containing protein. Indoleamine 2,3-dioxygenase 1 (IDO1) is an intracellular heme-containing dioxygenase which is associated with the immunosuppressive effects in cancer. With IDO1 as an example, herein we report a combined virtual screening (VS) strategy including high-specificity heme-binding group (HmBG)-based pharmacophore screening and cascade molecular docking to identify novel IDO1 inhibitors. A total of four hit compounds were obtained and showed proper binding with the heme iron coordinating site. Further structural optimization led to a promising compound S18-3, which exerted potent anti-tumor efficacy in BALB/c mice bearing established CT26 tumors by activating the host's immune system. These results suggest that S18-3 merits further study to assess its potential for the intervention of cancer. Furthermore, our study also unveils a novel in silico-based strategy for identifying potential regulators for hemeproteins within short timeframe.

A series of novel 4,5,6-trisubstituted pyrimidines were designed as potent covalent Bruton's tyrosine kinase (BTK) inhibitors based on the structure of ibrutinib by using a ring-opening strategy. Among these derivatives, compound I1 exhibited the most potent inhibitory activity with an IC50 value of 0.07μM. The preliminary structure-activity relationship was discussed and the primary amino group at the C-4 position of pyrimidine was crucial for maintaining BTK activity. Furthermore, molecular dynamics simulations and binding free energy calculations were performed for three inhibitor-BTK complexes to determine the probable binding model, which provided a comprehensive guide for further structural modification and optimization.

Dot1-like protein (DOT1L) is a histone methyltransferase that has become a novel and promising target for acute leukemias bearing mixed lineage leukemia (MLL) gene rearrangements. In this study, a hierarchical docking-based virtual screening combined with molecular dynamic (MD) simulation was performed to identify DOT1L inhibitors with novel scaffolds. Consequently, 8 top-ranked hits were eventually identified and were further subjected to MD simulation. It was indicated that all hits could reach equilibrium with DOT1L in the MD simulation and further binding free energy calculations suggested that phenoxyacetamide-derived hits such as L01, L03, L04 and L05 exhibited remarkably higher binding affinity compared to other hits. Among them, L03 showed both the lowest glide score (-12.281) and the most favorable binding free energy (-303.9+/-16.5kJ/mol), thereby making it a promising lead for further optimization.

Re2O7 catalyzed tandem allylic alcohol isomerization/oxa-Michael addition reaction of cyclohexadienone was developed. The reaction features a regioselective and stereoselective isomerization of allylic alcohol and diastereoselective ring closure via oxa-Michael addition. This method also enabled construction of enantiopure bicyclic enones from substrates incorporated with chiral allylic alcohol via efficient chirality transfer.

A series of hybrids from O(2)-(2,4-dinitrophenyl)diazeniumdiolate and oleanolic acid (OA) were designed, synthesized, and biologically evaluated as novel nitric oxide (NO)-releasing prodrugs that could be activated by glutathione S-transferase π (GSTπ) overexpressed in a number of cancer cells. It was discovered that the most active compound, 21, released high levels of NO selectively in HCC cells but not in the normal cells and exhibited potent antiproliferative activity in vitro as well as remarkable tumor-retarding effects in vivo. Compared with the reported GSTπ-activated prodrugs JS-K and PABA/NO, 21 exhibited remarkably improved stability in the absence of GSTπ. Importantly, the decomposition of 21 occurred in the presence of GSTπ and was much more effective than in glutathione S-transferase α. Additionally, 21 induced apoptosis in HepG2 cells by arresting the cell cycle at the G2/M phase, activating both the mitochondrion-mediated pathway and the MAPK pathway and enhancing the intracellular production of ROS.

Piperlongumine 1 increases reactive oxygen species (ROS) levels and preferably induces cancer cell apoptosis by triggering different pathways. However, the poor solubility of 1 limits its intensive investigation and clinical application. Ligustrazine possesses a water-soluble pyrazine skeleton and can inhibit proliferation and metastasis of cancer cells. We synthesized compound 3 by replacement of the trimethoxyphenyl of 1 with ligustrazine moiety and further introduced 2-Cl, -Br, and -I to 3 for synthesis of 4-6, respectively. Compound 4 possessed 14-fold greater aqueous solubility than 1 and increased ROS levels in colorectal cancer HCT-116 cells. Additionally, 4 preferably inhibited proliferation, migration, invasion, and heteroadhesion of HCT-116 cells. Treatment with 4 suppressed tumor growth and lung metastasis in vivo and prolonged the survival of tumor-bearing mice. Furthermore, 4 mitigated TGF-β1-induced epithelial-mesenchymal transition and Wnt/β-catenin activation by inhibiting the Akt and GSK-3β phosphorylation in HCT-116 cells. Collectively, 4 displayed significant antiproliferation and antimetastasis activities, superior to 1.

Currently, no effective and safe medicines are available to treat diabetic nephropathy (DN). Bardoxolone methyl (CDDO-Me) has displayed promising anti-DN activity as well as serious side effects in clinical trials, probably because the highly reactive α-cyano-α,β-unsaturated ketone (CUK) in ring A of CDDO-Me can covalently bind to thiol functionalities in many biomacromolecules. In this study, we designed and synthesized a γ-glutamyl transpeptidase (GGT)-based and CUK-modified derivative of CDDO-Me (2) to address this issue. 2 can be specifically cleaved by GGT, which is highly expressed in the kidney, to liberate CDDO-Me in situ. It should be noted that 2 exhibited anti-DN efficacy comparable to that of CDDO-Me with much less toxicity in cells and db/db mice, suggesting that its safety is better than CDDO-Me. Our findings not only reveal the therapeutic potential of 2 but also provide a strategy to optimize other synthetic molecules or natural products bearing a pharmacophore like CUK to achieve safer pharmaceutical drugs.

Dysregulation of the B-cell receptor (BCR) signaling pathway plays a vital role in the pathogenesis and development of B-cell malignancies. Bruton's tyrosine kinase (BTK), a key component in the BCR signaling, has been validated as a valuable target for the treatment of B-cell malignancies. In an attempt to find novel and potent BTK inhibitors, both ligand- and structure-based pharmacophore models were generated using Discovery Studio 2.5 and Ligandscout 3.11 with the aim of screening the ChemBridge database. The resulting hits were then subjected to sequential docking experiments using two independent docking programs, CDOCKER and Glide. Molecules displaying high glide scores and H-bond interactions with the key residue Met477 in both of the docking programs were retained. Drug-like criteria including Lipinski's rule of five and ADMET properties filters were employed for further refinement of the retrieved hits. By clustering, eight promising compounds with novel chemical scaffolds were finally selected and the top two ranking compounds were evaluated by molecular dynamics simulation. We believe that these compounds are of great potential in BTK inhibition and will be used for further investigation.

γ-Lactam is an important structural motif in a large number of biologically active natural products and synthetic small pharmaceutical molecules. However, there is currently no effective approach to construct γ-lactam ring directly from natural rigid polycyclic amides. Herein, we report a facile methodology for synthesis of a new group of olean-28,13β-lactams (10a-j) from their corresponding amides, promoted by an easily available reagent 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ), through an intramolecular dehydrogenative C-N coupling reaction via a radical ion mechanism. Biological evaluation indicated that the most active lactam 10h displayed potent antiproliferative activity against human cancer cells but 13.84- to 16.92-fold less inhibitory activity on noncancer cells in vitro. In addition, 10h significantly inhibited the growth of implanted prostate cancer in vivo. Furthermore, 10h induced cell cycle arrest and apoptosis and down-regulated the AKT/mTOR signaling in DU-145 cells. Finally, 10h was more stable in rat plasma and human liver microsomes than CDDO-Me and had little hERG channel inhibitory activity. Collectively, 10h may be a potential antiprostate cancer agent for further investigation.

A series of novel uracil and 5-fluorouracil-1-yl-acetic acid-colchicine derivatives(6a–6n) was synthesized via coupling uracil and 5-fluorouracil(5-FU) with C-10 analogues of colchicine. The antitumor activities of the target compounds against human hepatocellular carcinoma(BEL7402) cells, human ovary carcinoma(A2780) cells, human lung adenocarcinoma(A549) cells and human breast carcinoma(MCF7) cells were tested in vitro, and the structure-activity relationship(SAR) of the compounds was also studied. The bioassay results demonstrate that most of the tested compounds display significant activity and particularly, compounds 6a, 6e, 6h and 6l show more potent cytotoxic activities than 5-fluorouracil and colchicine. The results show that the new derivatives of colchicine are potential suppressors on human cancer.

By designing a novel chiral ion-pair organocatalyst composed of chiral phosphate and DABCO-derived quaternary ammonium, highly enantioselective 3-exo iodo-cycloetherification of allyl alcohols was achieved using NIS as a halogen source. Based on this reaction, one-pot asymmetric 3-exo iodo-cycloetherification/Wagner–Meerwein rearrangement of allyl alcohols en route to enantioenriched 2-iodomethyl-2-aryl cycloalkanones was subsequently developed. Due to the participation of adjacent iodine, the Wagner–Meerwein rearrangement of 2-iodomethyl-2-aryl epoxide proceeds with unusual retention of stereoconfiguration.

A group of nitric oxide (NO)-releasing derivatives of oleanolic acid (OA) (5–13) were designed, synthesized and biologically evaluated for their anti-colon cancer activity. It was found that the most potent compound 6 preferably released high levels of NO in colon cancer cells but not in normal cells, leading to potent cytotoxicity against colon cancer cells. In addition, 6 was more prone to produce NO catalyzed by GSTπ relative to GSTα. Furthermore, 6 significantly inhibited the tumor growth in a mouse xenograft model. Finally, 6 induced nitration of tyrosine residues in mitochondrial protein, down-regulated Wnt/β-catenin pathway, and inhibited COX-2 centered signaling loop in colon cancer cells. Collectively, our findings suggested that 6 could be a promising candidate for the intervention of colon cancer.

Indoleamine 2,3-dioxygenase 1 (IDO1) is frequently hijacked by tumors to escape the host immune response, and the enzyme is now firmly established as an attractive target for cancer immunotherapy. To identify novel IDO1 inhibitors suitable for drug development, a scaffold-hopping strategy combined with the average electrostatic potentials calculation was ultilized to design novel benzoxazolinone derivatives. Among these, compounds 7e, 7f and 9c exhibited the inhibitory potency in the low micromolar range and displayed negligible level of cytotoxicity against HeLa cells. Treatment with these three compounds promoted the proliferation of T lymphocyte and led to the dramatic decrease of regulatory T cells in the B16F1 cells and naive T cells co-culture system. Subsequent spectroscopic experiments suggested that these benzoxazolinones formed a coordinate bond with the heme iron to stabilize the complex. This study suggested that the benzoxazolinone was an interesting scaffold for discovering novel IDO1 inhibitors, and these compounds are attractive candidates for further development.

Highly asymmetric bromocyclization of tryptophol by using chiral anionic phase-transfer catalyst and DABCO-derived brominating reagent is described. Optimization of the reaction conditions revealed that the reaction rate was accelerated together with improvement of enantioselectivity by addition of catalytic DABCO-derived brominating reagent. From tryptophol, 3-bromofuroindoline could be directly obtained in excellent enantioselectivities by employing this novel methodology.

Indoleamine 2,3-dioxygenase 1 (IDO1) is regarded as an attractive target for cancer immunotherapy. To rationalize the detailed interactions between IDO1 and its inhibitors at the atomic level, an integrated computational approach by combining molecular mechanics and quantum mechanics methods was employed in this report. Specifically, the binding modes of 20 inhibitors was initially investigated using the induced fit docking (IFD) protocol, which outperformed other two docking protocols in terms of correctly predicting ligand conformations. Secondly, molecular dynamics (MD) simulations and MM/PBSA free energy calculations were employed to determine the dynamic binding process and crucial residues were confirmed through close contact analysis, hydrogen-bond analysis and binding free energy decomposition calculations. Subsequent quantum mechanics and nonbonding interaction analysis were carried out to provide in-depth explanations on the critical role of those key residues, and Arg231 and 7-propionate of the heme group were major contributors to ligand binding, which lowed a great amount of interaction energy. We anticipate that these findings will be valuable for enzymatic studies and rational drug design.

3-Oxo-29-noroleana-1,9(11),12-trien-2,20-dicarbonitrile (ONTD) is a novel synthetic derivative of glycyrrhetinic acid (GA), which has the ability to inhibit the proliferation of human hepatocellular carcinoma (HCC) cells. However, the mechanisms by which ONTD exerts its inhibitory effects remain elusive. The present study was conducted to investigate the cytotoxicity of ONTD in Bel-7402 cells and its molecular mechanisms. We found that ONTD depleted intracellular GSH, increased the level of ROS, and consequently induced mitochondrial permeability transition (MPT) leading to the release of apoptosis-inducing factor (AIF) and cytochrome c (Cyt c) to the cytosol. Mitochondrial alteration and subsequent apoptotic cell death in ONTD-treated Bel-7402 cells could be blocked by addition of exogenous antioxidants N-acetylcystein (NAC), GSH and the MTP inhibitor cyclosporin A (CsA). In addition, ONTD activated the phosphorylation of c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinases (MAPK) but not extracellular signal-regulated protein kinases (ERK 1/2). When the cells were exposed to SP600125 (a JNK inhibitor) and SB203580 (a p38 inhibitor), the deregulation of the expression of apoptotic proteins was attenuated. Furthermore, 40 mg/kg ONTD significantly reduced tumor weight (-70.62%, p0.01) in the H22 tumor-bearing mouse model in vivo. Taken together, these findings provide the first experimental evidence supporting that ONTD could induce apoptosis of Bel-7402 cells via MAPK-mediated mitochondrial pathway and ONTD has the potential to be developed as a therapeutic agent for the treatment of HCC.

A shorter path: A highly enantioselective bromocyclization of tryptamine has been developed using an anionic chiral phase-transfer catalyst. This method provides a direct approach for preparing chiral 3-bromopyrroloindoline from tryptamine, which enables a four-step enantioselective synthesis of (-)-chimonanthine. PG=protecting group.