非核苷逆转录酶抑制剂新进展

治疗艾滋病的逆转录酶抑制剂主要包括核苷逆转录酶抑制剂(NRTIs,如齐多夫定)和非核苷逆转录酶抑制剂(NNRTIs,如奈韦拉平)。目前至少有30多类非核苷类化合物被发现具有选择性抑制HIV-1逆转录酶的作用,其中已经获得美国FDA批准上市的包括奈韦拉平、地拉夫定和埃法韦伦,还有一些品种正在进行临床试验,其中效果较好的包括MKC-442、trovirdine、loviride等。“第一代”NNRTIs的缺点是容易使病毒产生变异,出现耐药性。“第二代”NNRTIs则活性谱广,不容易产生耐药的变异病毒。属于“第二代”NNRTIs的化合物除了埃法韦伦外,还包括埃法韦伦的衍生物DPC083,咪唑衍生物capravirine,二芳基嘧啶类化合物etravirine、rilpivirine。此外,还有一些喹喔啉、吡嗪酮类、烯基二芳基甲烷等也表现出很好的抗HIV活性。相信在不久的将来,将有更多更有效的非核苷逆转录酶抑制剂为人类的健康带来福音。     

Optimization of the Antiviral Potency and Lipophilicity of Halogenated 2,6‐Diarylpyridinamines as a Novel Class of HIV‐1 NNRTIS

Nineteen new halogenated diarylpyridinamine (DAPA) analogues modified at the phenoxy C‐ring were synthesized and evaluated for anti‐HIV activity and certain drug‐like properties. Ten compounds showed high anti‐HIV activity (EC₅₀<10 nM ). In particular, (E)‐6‐(2′′‐bromo‐4′′‐cyanovinyl‐6′′‐methoxy)phenoxy‐N²‐(4′‐cyanophenyl)pyridin‐2,3‐diamine ( 8 c ) displayed low‐nanomolar antiviral potency (3–7 nM ) against wild‐type and drug‐resistant viral strains bearing the E138K or K101E mutations, which are associated with resistance to rilvipirine ( 1 b ). Compound 8 c exhibited much lower resistance fold changes (RFC: 1.1–2.1) than 1 b (RFC: 11.8–13.0). Compound 8 c also exhibited better metabolic stability (in vitro half‐life) than 1 b in human liver microsomes, possessed low lipophilicity (clog D: 3.29; measured log P: 3.31), and had desirable lipophilic efficiency indices (LE>0.3, LLE>5, LELP<10). With balanced potency and drug‐like properties, 8 c merits further development as an anti‐HIV drug candidate.     

Design,Synthesis, and SAR of Naphthyl‐Substituted Diarylpyrimidines as Non‐Nucleoside Inhibitors of HIV‐1 Reverse Transcriptase

A series of 38 2‐naphthyl‐substituted diarylpyrimidine (DAPY) analogues, characterized by various substitution patterns on the pyrimidine and naphthalene rings, was synthesized in a straightforward fashion by means of parallel synthesis and evaluated as inhibitors of the HIV‐1 wild‐type and double mutant (K103N+Y181C) strains. Most of the compounds displayed strong activity against wild‐type HIV‐1. The most active compound, with a cyano group at position C6 on the naphthalene ring, exhibited activity against wild‐type HIV‐1 with an EC₅₀ value of 0.002 μM and against the double mutant strain with an EC₅₀ value of 0.24 μM ; the selectivity index (SI) against wild‐type is >180 000, the highest SI value among DAPY analogues. The structure–activity relationship (SAR) of the newly synthesized DAPYs is presented herein.     

Synthesis and anti-HIV activity of aryl-2-[(4-cyanophenyl)amino]-4-pyrimidinone hydrazones as potent non-nucleoside reverse transcriptase inhibitors

A series of novel diarylpyrimidines (DAPYs) with a ketone hydrazone substituent on the methylene linker between the pyrimidine nucleus and the aryl moiety at the C‐4 position were synthesized, and their antiviral activity against human immunodeficiency virus (HIV)‐1 in MT‐4 cells was evaluated. Most compounds of this class exhibited excellent activity against wild‐type HIV‐1, with EC₅₀ values in the range of 1.7–13.2 nM . Of these compounds, 2‐bromophenyl‐2‐[(4‐cyanophenyl)amino]‐4‐pyrimidinone hydrazone ( 9 k ) displayed the most potent anti‐HIV‐1 activity (EC₅₀=1.7±0.6 nM ), with excellent selectivity for infected over uninfected cells (SI=5762). In addition, the 4‐methyl phenyl analogue 9 d (EC₅₀=2.4±0.2 nM , SI=18461) showed broad spectrum HIV inhibitory activity, with EC₅₀ values of 2.4±0.2 nM against wild‐type HIV‐1, 5.3±0.4 μM against HIV‐1 double‐mutated strain RES056 (K103N+Y181C), and 5.5 μM against HIV‐2 ROD strain. Furthermore, structure–activity relationship (SAR) data and molecular modeling results for these compounds are also discussed.     

Identification of a Small‐Molecule Inhibitor of HIV‐1 Assembly that Targets the Phosphatidylinositol (4,5)‐bisphosphate Binding Site of the HIV‐1 Matrix Protein

The development of drug resistance remains a critical problem for current HIV‐1 antiviral therapies, creating a need for new inhibitors of HIV‐1 replication. We previously reported on a novel anti‐HIV‐1 compound, N²‐(phenoxyacetyl)‐N‐[4‐(1‐piperidinylcarbonyl)benzyl]glycinamide ( 14 ), that binds to the highly conserved phosphatidylinositol (4,5)‐bisphosphate (PI(4,5)P₂) binding pocket of the HIV‐1 matrix (MA) protein. In this study, we re‐evaluate the hits from the virtual screen used to identify compound 14 and test them directly in an HIV‐1 replication assay using primary human peripheral blood mononuclear cells. This study resulted in the identification of three new compounds with antiviral activity; 2‐(4‐{[3‐(4‐fluorophenyl)‐1,2,4‐oxadiazol‐5‐yl]methyl})‐1‐piperazinyl)‐N‐(4‐methylphenyl)acetamide ( 7 ), 3‐(2‐ethoxyphenyl)‐5‐[[4‐(4‐nitrophenyl)piperazin‐1‐yl]methyl]‐1,2,4‐oxadiazole ( 17 ), and N‐[4‐ethoxy‐3‐(1‐piperidinylsulfonyl)phenyl]‐2‐(imidazo[2,1‐b][1,3]thiazol‐6‐yl)acetamide ( 18 ), with compound 7 being the most potent of these hits. Mechanistic studies on 7 demonstrated that it directly interacts with and functions through HIV‐1 MA. In accordance with our drug target, compound 7 competes with PI(4,5)P₂ for MA binding and, as a result, diminishes the production of new virus. Mutation of residues within the PI(4,5)P₂ binding site of MA decreased the antiviral effect of compound 7 . Additionally, compound 7 displays a broadly neutralizing anti‐HIV activity, with IC₅₀ values of 7.5–15.6 μM for the group M isolates tested. Taken together, these results point towards a novel chemical probe that can be used to more closely study the biological role of MA and could, through further optimization, lead to a new class of anti‐HIV‐1 therapeutics.     

6,7‐Dimethoxy‐2‐{2‐[4‐(1H‐1,2,3‐triazol‐1‐yl)phenyl]ethyl}‐1,2,3,4‐tetrahydroisoquinolines as Superior Reversal Agents for P‐Glycoprotein‐Mediated Multidrug Resistance

P‐glycoprotein (P‐gp)‐mediated multidrug resistance (MDR) is a major obstacle for successful cancer chemotherapy. Based on our previous study, 17 novel compounds with the 6,7‐dimethoxy‐2‐{2‐[4‐(1H‐1,2,3‐triazol‐1‐yl)phenyl]ethyl}‐1,2,3,4‐tetrahydroisoquinoline scaffold were designed and synthesized. Among them, 2‐[(1‐{4‐[2‐(6,7‐dimethoxy‐3,4‐dihydroisoquinolin‐2(1H)‐yl)ethyl]phenyl}‐1H‐1,2,3‐triazol‐4‐yl)methoxy]‐N‐(p‐tolyl)benzamide (compound 7 h ) was identified as a potent modulator of P‐gp‐mediated MDR, with high potency (EC₅₀=127.5±9.1 nM ), low cytotoxicity (TI>784.3), and long duration (>24 h) in reversing doxorubicin (DOX) resistance in K562/A02 cells. Compound 7 h also enhanced the effects of other MDR‐related cytotoxic agents (paclitaxel, vinblastine, and daunorubicin), increased the accumulation of DOX and blocked P‐gp‐mediated rhodamine 123 efflux function in K562/A02 MDR cells. Moreover, 7 h did not have any effect on cytochrome (CYP3A4) activity. These results indicate that 7 h is a relatively safe modulator of P‐gp‐mediated MDR that has good potential for further development.     

Comparing the Antileishmanial Activity of Gold(I) and Gold(III) Compounds in L. amazonensis and L. braziliensis in Vitro

Abstract : A series of mononuclear coordination or organometallic Au^I/Au^III complexes ( 1 – 9 ) have been comparatively studied in vitro for their antileishmanial activity against promastigotes and amastigotes, the clinically relevant parasite form, of Leishmania amazonensis and Leishmania braziliensis. One of the cationic Au^I bis-N-heterocyclic carbenes ( 3 ) has low EC₅₀ values (ca. 4 μM) in promastigotes cells and no toxicity in host macrophages. Together with two other Au^III complexes ( 6 and 7 ), the compound is also extremely effective in intracellular amastigotes from L. amazonensis. Initial mechanistic studies include an evaluation of the gold complexes′ effect on L. amazonensis’ plasma membrane integrity.     

Structural and Thermal Characterization of A Novel High Nitrogen Energetic Material: (NH4)2DNMT

1,4‐Dihydro‐5H‐(dinitromethylene)‐tetrazole ammonium salt ((NH₄)₂DNMT), a high nitrogen energetic compound, was synthesized and structurally characterized by single‐crystal X‐ray diffraction. The thermal behavior of (NH₄)₂DNMT was studied with DSC and TG‐DTG methods. The kinetic equation of the thermal decomposition reaction is: dα/dT=10^13.17/3β(1−α)⁻² exp(−1.388×10⁵/RT). The critical temperature of thermal explosion is 182.7 °C. The specific heat capacity of (NH₄)₂DNMT was determined and the molar heat capacity is 301 J mol⁻¹ K⁻¹ at 298.15 K. The adiabatic time‐to‐explosion of (NH₄)₂DNMT was calculated to be 277 s. The detonation velocity and detonation pressure were also estimated. All results showed that (NH₄)₂DNMT presents good performance.     

Thiuram Disulfides as Pseudo‐irreversible Inhibitors of Lymphoid Tyrosine Phosphatase

We screened a small library of thiuram disulfides for inhibition of lymphoid tyrosine phosphatase (LYP) activity. The parent thiuram disulfide, disulfiram, inhibited LYP activity in vitro and in Jurkat T cells, whereas diethyldithiocarbamate failed to inhibit LYP at the concentrations tested. Compound 13 , an N‐(2‐thioxothiazolidin‐4‐one) analogue, was found to be the most potent LYP inhibitor in this series, with an IC₅₀ value of 3 μM . Compound 13 inhibits LYP pseudo‐irreversibly, as evidenced by the time‐dependence of inhibition, with a K_i value of 1.1 μM and a k_inact value of 0.004 s^?1. The inhibition of LYP by compound 13 could not be reversed significantly by incubation with glutathione or by prolonged dialysis, but could be partially reversed by incubation with dithiothreitol. Compound 13 also inhibited LYP activity in Jurkat T cells.     

Synthesis and Evaluation of 1‐(1‐(Benzo[b]thiophen‐2‐yl)cyclohexyl)piperidine (BTCP) Analogues as Inhibitors of Trypanothione Reductase

Thirty two analogues of phencyclidine were synthesised and tested as inhibitors of trypanothione reductase (TryR), a potential drug target in trypanosome and leishmania parasites. The lead compound BTCP ( 1 , 1‐(1‐benzo[b]thiophen‐2‐yl‐cyclohexyl) piperidine) was found to be a competitive inhibitor of the enzyme (K_i=1 μM ) and biologically active against bloodstream T. brucei (EC₅₀=10 μM ), but with poor selectivity against mammalian MRC5 cells (EC₅₀=29 μM ). Analogues with improved enzymatic and biological activity were obtained. The structure–activity relationships of this novel series are discussed.     

Designing Dual Transglutaminase 2/Histone Deacetylase Inhibitors Effective at Halting Neuronal Death

In recent years there has been a clear consensus that neurodegenerative conditions can be better treated through concurrent modulation of different targets. Herein we report that combined inhibition of transglutaminase 2 (TG2) and histone deacetylases (HDACs) synergistically protects against toxic stimuli mediated by glutamate. Based on these findings, we designed and synthesized a series of novel dual TG2–HDAC binding agents. Compound 3 [(E)‐N‐hydroxy‐5‐(3‐(4‐(3‐oxo‐3‐(pyridin‐3‐yl)prop‐1‐en‐1‐yl)phenyl)thioureido)pentanamide] emerged as the most interesting of the series, being able to inhibit TG2 and HDACs both in vitro (TG2 IC₅₀=13.3±1.5 μm , HDAC1 IC₅₀=3.38±0.14 μm , HDAC6 IC₅₀=4.10±0.13 μm ) and in cell‐based assays. Furthermore, compound 3 does not exert any toxic effects in cortical neurons up to 50 μm and protects neurons against toxic insults induced by glutamate (5 mm ) with an EC₅₀ value of 3.7±0.5 μm .     

Anticancer Properties of Halogenated Pyrrolo[3,2‐d]pyrimidines with Decreased Toxicity via N5 Substitution

Halogenated pyrrolo[3,2‐d]pyrimidine analogues have shown antiproliferative activity in recent studies, with cell accumulation occurring in the G₂/M stage without apoptosis. However, the mechanism of action and pharmacokinetic (PK) profile of these compounds has yet to be determined. To investigate the PK profile of these compounds, a series of halogenated pyrrolo[3,2‐d]pyrimidine compounds was synthesized and first tested for activity in various cancer cell lines followed by a mouse model. EC₅₀ values ranged from 0.014 to 14.5 μm , and maximum tolerated doses (MTD) in mice were between 5 and 10 mg kg^?1. This indicates a wide variance in activity and toxicity that necessitates further study. To decrease toxicity, a second series of compounds was synthesized with N5‐alkyl substitutions in an effort to slow the rate of metabolism, which was thought to be leading to the toxicity. The N‐substituted compounds demonstrated comparable cell line activity (EC₅₀ values between 0.83–7.3 μm ) with significantly decreased toxicity (MTD=40 mg kg^?1). Finally, the PK profile of the active N5‐substituted compound shows a plasma half‐life of 32.7 minutes, and rapid conversion into the parent unsubstituted analogue. Together, these data indicate that halogenated pyrrolo[3,2‐d]pyrimidines present a promising lead into potent antiproliferative agents with tunable activity and toxicity, and rapid metabolism.     

β-D-Glucosyl Conjugates of Highly Potent Inhibitors of Blood Coagulation Factor Xa Bearing 2-Chorothiophene as a P1 Motif

We synthesized a novel O‐glucoside of the recently reported potent factor Xa (fXa) inhibitor 1 , which bears a 5‐chlorothien‐2‐yl moiety and 1‐isopropylpiperidine as fragments that bind the S1 and S4 enzyme pockets, respectively. A β‐D ‐glucosyl unit was conjugated through an ether‐linked C3‐alkyl spacer to the central phenyl ring of 1 . The synthesized β‐D ‐glucose‐based compound 16 achieved picomolar inhibitory potency against human fXa (K_i=60 pM ) and high selectivity over thrombin and other serine proteases. In addition to the chlorothienyl S1 binder, a large gain in ΔG resulted from the addition of protonated 1‐isopropylpiperidine (ΔΔG=29.7–30.5 kJ mol^?1), which should bind to the aromatic S4 pocket through efficient cation–π and C? H???π interactions. Instead, the C3‐alkyl‐linked glucose fragment, which is likely directed toward the solvent outside the enzyme binding site, improves ΔG by an average of 2.9–3.8 kJ mol^?1. Compound 16 showed sub‐micromolar in vitro anticoagulant activity, as assessed by prothrombin time (PT) and activated thromboplastin time (aPTT) clotting assays in pooled human plasma (PT₂ and aPTT₂ equal to 0.135 and 0.389 μM , respectively). Although compound 16 was 1.4‐fold less active than parent compound 1 in the ex vivo anticoagulant assay in mice, it showed a significant (1.6‐fold) prolongation of PT relative to controls (P<0.05) 60 min after oral dosing (75 mg kg^?1).     

Single Heteroatom Substitutions in the Efavirenz Oxazinone Ring Impact Metabolism by CYP2B6

Previously, we observed that the oxazinone ring is important for cytochrome P450 2B6 (CYP2B6) activity toward efavirenz ((4S)‐6‐chloro‐4‐(2‐cyclopropylethynyl)‐1,4‐dihydro‐4‐(trifluoromethyl)‐2H‐3,1‐benzoxazin‐2‐one), a CYP2B6 substrate used to treat HIV. To further understand the structural characteristics of efavirenz that render it a CYP2B6 substrate, we tested the importance of each heteroatom of the oxazinone ring. We assembled a panel of five analogues: 6‐chloro‐4‐(2‐cyclopropylethynyl)‐1,4‐dihydro‐2‐methyl‐4‐(trifluoromethyl)‐2H‐3,1‐benzoxazine ( 1 ), (4S)‐6‐chloro‐4‐[(1E)‐2‐cyclopropylethenyl]‐3,4‐dihydro‐4‐(trifluoromethyl)‐2(1H)‐quinazolinone ( 2 ), (4S)‐6‐chloro‐4‐(2‐cyclopropylethynyl)‐3,4‐dihydro‐4‐(trifluoromethyl)‐2(1H)‐quinazolinone ( 3 ), 6‐chloro‐4‐(cyclopropylethynyl)‐3,4‐dihydro‐4‐(trifluoromethyl)‐2(1H)‐quinolinone ( 4 ), and 6‐chloro‐4‐(cyclopropylethynyl)‐4‐(trifluoromethyl)‐4H‐benzo[d][1,3]dioxin‐2‐one ( 5 ). The metabolism of compounds 1 – 5 was investigated using human liver microsomes, individual P450s, and mass spectrometry or UV/Vis absorbance detection. Steady‐state analysis of CYP2B6 metabolism of 1 – 5 showed K_M values ranging from 0.3‐ to 3.9‐fold different from that observed for efavirenz (K_M: 3.6±1.7 μm ). The lowest K_M values, approximating 1 μm , were observed for the metabolism of 1 , whereas the greatest K_M value, 14±6.4 μm , was found for 4 . Our work reveals that analogues with heteroatom changes in the oxazinone ring are still CYP2B6 substrates, although the changes in K_M suggest altered substrate binding.     

[(μ-Fluoro) bis{(triphenyl) (p-tolyl) antimony}] iodide

The crystal structure of the mixed halide compound, [Ph₃(p-tolyl)Sb]F_0.5I_0.5 (4), obtained from [Ph₃(p-tolyl)Sb] [BF₄] and NaI, has been determined. Compound 4 is an ionic compound with a novel fluoride bridged cation, [Ph₃(p-tolyl)SbFSb (p-tolyl)Ph₃]⁺, and an independent I⁻ anion. The geometry of the Sb centres in the centrosymmetric cation is distorted trigonal bipyramidal with the axial sites occupied by a phenyl group [SbC(7) = 2.127(8) Å] and the bridging fluoride [SbF = 2.2856 (11) Å]; the C(7)-SbF angle is 177.6(2) °. The average SbC(equatorial) bond length of 2.099 Å is only slightly less than the SbC(axial) bond length.     

Probing the Peptidylglycine α‐Hydroxylating Monooxygenase Active Site with Novel 4‐Phenyl‐3‐butenoic Acid Based Inhibitors

Specific inhibition of the copper‐containing peptidylglycine α‐hydroxylating monooxygenase (PHM), which catalyzes the post‐translational modification of peptides involved in carcinogenesis and tumor progression, constitutes a new approach for combating cancer. We carried out a structure–activity study of new compounds derived from a well‐known PHM substrate analogue, the olefinic compound 4‐phenyl‐3‐butenoic acid (PBA). We designed, synthesized, and tested various PBA derivatives both in vitro and in silico. We show that it is possible to increase PBA affinity for PHM by appropriate functionalization of its aromatic nucleus. Compound 2 d , for example, bears a meta‐benzyloxy substituent, and exhibits better inhibition features (K_i=3.9 μM , k_inact/K_i=427 M ^?1 s^?1) than the parent PBA (K_i=19 μM , k_inact/K_i=82 M ^?1 s^?1). Docking calculations also suggest two different binding modes for PBA derivatives; these results will aid in the development of further PHM inhibitors with improved features.