尼拉帕尼：聚腺苷二磷酸-核糖聚合酶抑制剂

尼拉帕尼（Niraparib,商品名Zejula^TM）是聚腺苷二磷酸-核糖聚合酶（PARP）的口服小分子抑制剂,PARP抑制是治疗由DNA修复基因（如BRCA1和BRCA2）特异性畸变引起的DNA修复机制缺陷的癌症的有效策略。尼拉帕尼于2017年3月在美国获批,维持治疗复发性上皮性卵巢癌、输卵管癌、原发性腹膜癌的成年患者,这些患者对铂类化疗有完全或部分反应,推荐剂量为口服300 mg/d,直到疾病发生恶化或产生无法接受的不良反应。临床研究结果表明该药可以延长患者的无恶化生存期,为治疗卵巢癌提供了有效和可靠的治疗手段。     

Characterization of adenosine deaminase from the malarial parasite, Plasmodium lophurae, and its host cell,the duckling erythrocyte

Adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) was purified and characterized from the malarial parasite, Plasmodium lophurae, and its host cell, the duck (Anas domesticus) erythrocyte, using chromatofocusing (Pharmacia) and adenosine affinity columns. Gel filtration of the enzymes gave molecular weights of 33,800 (P. lophurae) and 36,500 (duck erythrocyte); both enzymes had broad pH optima (pH 6.8 to 8.0), similar stabilities when stored as crude lysates, and like K_m values with adenosine: 2.74 ± 0.88 × 10^?5 M (parasite) and 1.74 ± 0.27 × 10^?5 M (erythrocyte). The P. lophurae adenosine deaminase had a pI of 5.37 ± 0.09, and the duck erythrocyte enzyme had a pI of 4.72 ± 0.09, as determined by chromatofocusing. The parasite enzyme exhibited a specific activity in the crude lysate that was an average 60-fold higher than that of the erythrocyte enzyme. The pattern of elution from the adenosine affinity column, as well as kinetic studies with three adenosine analogs, revealed distinct differences in the binding characteristics of the two enzymes. The P. lophurae adenosine deaminase was weakly retarded by the affinity column, whereas the duck erythrocyte enzyme was strongly retarded. With 9-β-d-arabinosyladenine as substrate, the K_m values were similar (2.29 ± 0.98 × 10^?4 M for P. lophurae and 1.10 ± 0.21 × 10^?4 M for the duck erythrocyte). Erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) was a potent inhibitor of the duck erythrocyte enzyme with 100% inhibition at 1.3 μM, whereas the parasite adenosine deaminase was not inhibited at 422 μM even when incubated for 24 hr. Inhibitor studies with coformycin, a tight-binding inhibitor, resulted in K_i values of 7.14 × 10^?11 M for P. lophurae and 1.86 × 10^?10 M for the duck erythrocyte. The molar equivalencies, E_t, and catalytic numbers, k₃, were slightly different for both enzymes. The E_t values were 2.80 × 10^?10 M (P. lophurae) and 3.13 × 10^?10 M (duck erythrocyte); the k₃ values were 5.18 × 10³ min^?1 and 4.36 × 10³ min^?1 respectively.     

Broad-spectrum antiviral activity of adenosine analogues

In recent years certain aliphatic and carbocyclic adenosine analogues have been developed which are of potential clinical importance as antiviral agents. This includes (S)-9-(2,3-dihydroxypropyl)adenine [(S)-DHPA] and carbocyclic 3-deazaadenosine (C-c3Ado). (S)-DHPA and C-c3Ado are remarkably similar in their antiviral spectrum in that they are particularly active against (-) RNA viruses such as measles, para-influenza, respiratory syncytial virus, rabies virus, vesicular stomatitis virus and (+/-)RNA viruses such as reo- and rotavirus, whereas (+)RNA viruses such as polio, coxsackie and (+/-)DNA viruses such as herpes simplex are only minimally affected or not inhibited at all. In contrast with (S)-DHPA and C-c3Ado which are quite selective in their antiviral action, other adenosine analogues, i.e., 3-deazaadenosine and 7-deazaadenosine (tubercidin), exhibit little, if any, selectivity as antiviral agents. Also, tubercidin has a broader activity spectrum, encompassing (+)RNA viruses as well as herpes simplex in addition to the (-)RNA viruses. Considering the high antiviral potency of tubercidin, attempts have been undertaken to increase its selectivity, i.e., by chemical substitutions at C-5 of the pyrrolo(2,3-d)pyrimidine ring. These attempts have been partially successful.     

Reinforcement of antitumor effect of Cordyceps sinensis by 2'-deoxycoformycin, an adenosine deaminase inhibitor

In this study, an attempt was made to elucidate the combined effect of 2'-deoxycoformycin (DCF), an adenosine deaminase inhibitor, with a water extract of Cordyceps sinensis (WECS), on the growth curves of mouse melanoma and lung carcinoma cells. Sub-confluent cells were harvested with an EDTA trypsin solution, and resuspended to appropriate concentrations in DMEM containing 10% fetal bovine serum. Using 1x10(5) cells/2 ml in each well of a 12-well culture plate, cells were incubated for 24, 48 and 72 h in the presence of WECS alone, or WECS plus DCF in a CO2 incubator at 37 degrees C. Duplicate samples of viable cells were enumerated with a Coulter counter. The antitumor effect of WECS on the growth curves of tumor cell lines increased over 3-fold in combination with DCF. These results suggest that DCF has a remarkable reinforcement effect on the antitumor activity of WECS. DCF is a potent adjuvant for WECS.     

Novel antiviral agents: phosphoramidates or mono/di/tri-phosphate esters of carbocyclic adenosine analogues

The patent application describes new compounds, their preparation processes and methods for their use in treating viral infections (particularly hepatitis B) and retroviral infections (particularly HIV). The anti-HIV activity in MT₄ cells is claimed to be in the range pM to μM.     

Oroxylin A,a classical natural product,shows a novel inhibitory effect on angiogenesis induced by lipopolysaccharide

BackgroundThere is an obvious relationship among angiogenesis and inflammation. From previous study, we learn that oroxylin A possesses anti-angiogenic activity in vitro and in ovo. It also has an inhibitory effect on inflammation. But whether oroxylin A suppresses the inflammation-induced angiogenesis is still unknown. Our present study focuses on the role of oroxylin A in targeting LPS-induced angiogenesis, inflammatory and related pathways.MethodsThe effects of oroxylin A on angiogenesis were investigated by transwell assay, tube formation assay, rat aortic ring assay and chorioallantoic membrane (CAM) model. Western blotting analysis was used to detect the expression of certain proteins.ResultsWe found that oroxylin A inhibited LPS-induced migration and tube formation of human umbilical vein endothelial cells (HUVECs), as well as microvessel sprouting from rat aotric ring in vitro and the angiogenesis of chicken chorioallantoic membrane (CAM) model in ovo. The results also indicated that oroxylin A could inhibit the expression of LPS acceptor toll-like receptor 4 (TLR4) and the activities of its downstream mitogen-activated protein kinases (MAPKs), including reducing expressions of the phosphorylation of JNK, p38, and ERK. Moreover, oroxylin A prevented NF-κB dimers from translocating to the nucleus.ConclusionsTaken together, oroxylin A can suppress the angiogenesis induced by LPS and it may affect the LPS/TLR4 signaling pathway.     

重楼皂苷的制备及其抗A型流感病毒活性

目的研究重楼皂苷的制备及体内外对A型流感病毒(IAV)活性的影响。方法 采用柱层析和反相液相色谱分离技术,从重楼中提取重楼皂苷Ⅰ,Ⅱ,Ⅵ和Ⅶ,应用高效液相色谱法测定其纯度。采用MTT比色法测定重楼皂苷Ⅰ,Ⅱ,Ⅵ和Ⅶ的细胞毒性,并检测其体外对IAV的直接灭活作用、对IAV吸附和侵入细胞的阻断作用及对IAV在靶细胞内增殖的抑制作用。用IAV滴鼻法制备IAV感染小鼠模型,模型制备4 h后分别每天ig给予重楼皂苷Ⅰ5和10 mg.kg-1及阳性对照药奥司他韦3 mg.kg-1,每天分2次给药,连续5 d,自给药后每天观察并记录小鼠发病情况和死亡数,共观察14 d,计算小鼠死亡率和生命延长率,评价其体内抗IAV作用。结果 提取分离得到的重楼皂苷Ⅰ,Ⅱ,Ⅵ和Ⅶ的纯度分别为95.3%,90.2%,92.4%和86.8%。重楼皂苷Ⅰ,Ⅱ,Ⅵ和Ⅶ浓度分别低于50,12.5,6.25和12.5 mg.L-1时,未见对靶细胞MDCK的细胞毒性。重楼皂苷Ⅰ6.25,12.5,25和50 mg.L-1,重楼皂苷Ⅱ6.25和12.5 mg.L-1,重楼皂苷Ⅵ3.13和6.25 mg.L-1,重楼皂苷Ⅶ6.25和12.5 mg.L-1及奥司他韦40 mg.L-1对IAV均有显著的直接灭活作用(P<0.01),对IAV吸附和侵入靶细胞亦具有一定的阻断作用(P<0.01),对IAV在靶细胞内的增殖具有抑制作用(P<0.01)。重楼皂苷Ⅰ5和10 mg.L-1可明显降低IAV感染小鼠的死亡率(P<0.01),由流感病毒感染组的8/10均下降到2/10;并可延长IAV感染小鼠的存活时间(P<0.01),存活时间由(8.5±0.3)d分别延长到12.7±0.4和(13.2±0.5)d(P<0.01),生命延长率分别为49.4%和55.3%,效果与奥司他韦近似。结论 从植物重楼中分离到高纯度的重楼皂苷Ⅰ,Ⅱ,Ⅵ和Ⅶ,重楼皂苷Ⅱ,Ⅵ和Ⅶ在体外具有较好的抗IAV活性,重楼皂苷Ⅰ在体内外均具有较好的抗IAV活性。     

Pharmacokinetics of 2'-deoxycoformycin, an inhibitor of adenosine deaminase, in the rat

The distribution of the potent inhibitor of adenosine deaminase (ADA), 2'-deoxycoformycin (DCF), in the brain of the rat and its inhibition of ADA in brain and gut was determined. The accumulation of [3H]DCF in brain was maximal 2 hr after intraperitoneal injection and elimination was best described by a two compartment model having t1/2 phases of about 1-5 hr and 50 hr. The activity of ADA in gut exhibited dose-related inhibition at 1.9, 3.7 and 18.6 mumol/kg (i.p.) and returned to normal by 16 days. In brain, ADA was inhibited by about 95% at all three of these doses of DCF 2 hr after injection and activity returned to control levels by 30 days with the two smaller doses, but remained at 66% of control levels at 50 days with 18.6 mumol/kg. The t1/2 of the recovery of the activity of ADA in both brain and gut was found to be dose-dependent. The failure of the activity of ADA in brain to recover after treatment with 18.6 mumol/kg suggests either long-term down-regulation of the expression of ADA or irreversible damage to ADA-containing neurons.     

Potentiation of formalin-evoked adenosine release by an adenosine kinase inhibitor and an adenosine deaminase inhibitor in the rat hind paw: a microdialysis study

The present study examined the effects of local subcutaneous administration of formalin on adenosine release from the rat hind paw, and the effects of inhibitors of adenosine metabolism on such release. Microdialysis probes were inserted into the subcutaneous tissue of the plantar surface of rat hind paws. Samples were collected every 10 min at a perfusion rate of 2 microl/min and high performance liquid chromatography was used to measure adenosine levels. At lower concentrations of formalin (0.5-2.5%), a significant increase in adenosine levels was observed in the first 10 min after formalin injection, while at the highest concentration of formalin (5%), the increase in adenosine release was observed over 60 min. Co-administration of the adenosine kinase inhibitor 5'-amino-5'-deoxyadenosine (100 nmol) with formalin, significantly increased adenosine release evoked by 0.5-1.5% formalin, but did not produce a further enhancement of release evoked by 5% formalin. The adenosine deaminase inhibitor 2'-deoxycoformycin (100 nmol) significantly increased adenosine levels at 5% formalin but had no effect at lower concentrations of formalin. In confirmation of previous studies, subcutaneous injection of formalin (0.5-5%) produced a characteristic biphasic concentration-related expression of nociceptive behaviours and an increase in paw volume. This study directly demonstrates that formalin can evoke a concentration-dependent local release of adenosine from the rat hind paw. The ability of an adenosine kinase inhibitor and an adenosine deaminase inhibitor to modulate this release is dependent on substrate adenosine concentrations.     

Cyclosporin A analogues: recent advances

Cyclosporin A (Sandimmune^®, Neoral^®; Novartis) is a cyclic hydrophobic undecapeptide used to prevent and treat organ transplantation rejection. Cyclosporin A has potential therapeutic applications in the treatment of diseases such as asthma, psoriasis, atopic dermatitis and rheumatoid arthritis, but its wide use is limited by its poor bioavaliability and toxicity, the most significant of which is nephrotoxicity. There has been a tremendous research effort in producing cyclosporin analogues with better pharmacological profiles. This paper will give a general overview of the recent advances (1999 – 2002) made in producing novel semisynthetic cyclosporin analogues with improved bioavailability and therapeutic index.     

Neurotrophic actions of the novel AMPA receptor potentiator, LY404187, in rodent models of Parkinson's disease

Recent developments in the molecular biology and pharmacology of alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors has led to the discovery of selective, potent and systemically active AMPA receptor potentiators. These molecules enhance synaptic transmission and evidence suggests that they play important roles in plasticity and cognitive processes. Activation of AMPA receptors also increases neuronal activation and activity-dependent signalling, which may increase brain-derived neurotrophic factor (BDNF) expression and enhance cell proliferation in the brain. We therefore hypothesised that an AMPA receptor potentiator may provide neurotrophic effects in rodent models of Parkinson's disease. In the present studies we report that the potent and selective AMPA receptor potentiator, R,S-N-2-(4-(4-Cyanophenyl)phenyl)propyl 2-propanesulfonamide (LY404187), provides both functional, neurochemical and histological protection against unilateral infusion of 6-hydroxydopamine into the substantia nigra or striatum of rats. The compound also reduced 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced toxicity in mice. Interestingly, we were also able to observe large functional and histological effects when we delayed treatment until after cell death had occurred (3 or 6 days after 6-hydroxydopamine infusion), supporting a neurotrophic mechanism of action. In addition, LY404187 provided a dose-dependent increase in growth-associated protein-43 expression in the striatum. Therefore, we propose that AMPA receptor potentiators offer the potential of a new therapy to halt the progression and perhaps repair the degeneration in Parkinson's disease.     

Tight-binding inhibitors—III: A new approach for the determination of competition between tight-binding inhibitors and substrates—inhibition of adenosine deaminase by coformycin

Equations have been developed which provide the basis for the elucidation of the inhibition mechanism of a tight-binding inhibitor by studying the manner in which the substrate interferes with the bincling of the inhibitor to the enzyme. The procedure involves the determination of the pseudo-firstorder rate constants at various concentrations of the substrate and the inhibitor. This method is applicable to very tightly binding inhibitors, including irreversible inhibitors. Methods for the graphical as well as statistical analyses of the data are presented. By the application of these methods, it is demonstrated that coformycin competes with adenosine for adenosine deaminase from calf intestinal mucosa. The kinetic parameters ( ± S. E.) for the bincling of coformycin with adenosine deaminase were determined at 22° and pH 7.4; the second-order rate constant, 1.01 ( ± 0.06) × 10⁶0MP^?1 sec^?1; the first-order rate constant, 2.2 ( ± 1.0) × 10^?4sec^?1; and the dissociation constant of the EI complex, 2.2 ( ± 0.76) × 10^?10 M.     

Physalin B, a novel inhibitor of the ubiquitin-proteasome pathway, triggers NOXA-associated apoptosis

The ubiquitin-proteasome pathway plays a critical role in the degradation of proteins involved in tumor growth and has therefore become a target for cancer therapy. In order to discover novel inhibitors of this pathway, a cellular assay reporter of proteasome activity was established. Human DLD-1 colon cancer cells were engineered to express a 4 ubiquitin-luciferase (DLD-1 4Ub-Luc) reporter protein, rapidly degraded via the ubiquitin-proteasome pathway and designed DLD-1 4Ub-Luc cells. Following treatment with reference proteasome inhibitors, the 4Ub-Luc protein accumulated in DLD-1 4Ub-Luc cells and a 80-fold increase in luciferase-produced bioluminescence signal was measured, as compared to untreated cells. The screening of over 30,000 compounds using this DLD-1 4Ub-Luc assay led to the identification of physalin B as a novel inhibitor of the ubiquitin-proteasome pathway. Indeed, physalin B induced an increase in bioluminescence from DLD-1 4Ub-Luc cells, at concentrations also producing an accumulation of ubiquitinated proteins and inhibiting TNFalpha-induced NF-kappaB activation. Physalin B did not inhibit catalytic activities of purified proteasome and interfered with cellular proteasomal catalytic activities at 4- to 8-fold higher concentrations than that required to induce significant increase in bioluminescence and accumulation of ubiquitinated proteins in DLD-1 4Ub-Luc cells. Furthermore, physalin B proved to be cytotoxic, triggered apoptosis in DLD-1 4Ub-Luc cells and induced the proapoptotic protein NOXA, characteristic of the proteasome signaling pathway. Therefore, the use of the DLD-1 4Ub-Luc assay allowed the identification of a novel inhibitor of the ubiquitin-proteasome pathway that might interfere with proteasome functions in a different way from reference proteasome inhibitors.     

BGP-15 - a novel poly(ADP-ribose) polymerase inhibitor - protects against nephrotoxicity of cisplatin without compromising its antitumor activity

Nephrotoxicity is one of the major dose limiting side effects of cisplatin chemotherapy. The antitumor and toxic effects are mediated in part by different mechanisms, thus, permitting a selective inhibition of certain side effects. The influence of O-(3-piperidino-2-hydroxy-1-propyl)nicotinic amidoxime (BGP-15) - a poly(ADP-ribose) polymerase (PARP) inhibitor - on the nephrotoxicity and antitumor efficacy of cisplatin has been evaluated in experimental models. BGP-15 either blocked or significantly reduced (60-90% in 100-200 mg/kg oral dose) cisplatin induced increase in serum urea and creatinine level in mice and rats and prevented the structural degeneration of the kidney, as well. The nephroprotective effect of BGP-15 treatment was revealed also in living mice by MRI analysis manifesting in the lack of oedema which otherwise developed as a result of cisplatin treatment. The protective effect was accompanied by inhibition of cisplatin-induced poly-ADP-ribosylation and by the restoration of the disturbed energy metabolism. The preservation of ATP level in the kidney was demonstrated in vivo by localized NMR spectroscopy. BGP-15 decreased cisplatin-induced ROS production in rat kidney mitochondria and improved the antioxidant status of the kidney in mice with cisplatin-induced nephropathy. In rat kidney, cisplatin caused a decrease in the level of Bcl-x, a mitochondrial protective protein, and this was normalized by BGP-15 treatment. On the other hand, BGP-15 did not inhibit the antitumor efficacy of cisplatin in cell culture and in transplantable solid tumors of mice. Treatment with BGP-15 increased the mean survival time of cisplatin-treated P-388 leukemia bearing mice from 13 to 19 days. PARP inhibitors have been demonstrated to diminish the consequences of free radical-induced damage, and this is related to the chemoprotective effect of BGP-15, a novel PARP inhibitor. Based on these results, we propose that BGP-15 represents a novel, non-thiol chemoprotective agent.     

A novel inhibitor of the new antibiotic resistance protein OptrA

The antibiotic resistance (ARE) subfamily of ABC (ATP‐binding cassette) proteins confers resistance to a variety of clinically important ribosome‐targeting antibiotics and plays an important role in infections caused by pathogenic bacteria. However, inhibitors of ARE proteins have rarely been reported. Here, OptrA, a new member of the ARE proteins, was used to study inhibitors of these types of proteins. We first confirmed that destroying the catalytic activity of OptrA could restore the sensitivity of host cells to antibiotics. Then, fragment‐based screening, a drug screening method, was used to screen for inhibitors of OptrA. The competitive saturation transfer difference experiments, docking, and molecular dynamics were used to determine the binding sites and mode of interactions between OptrA and fragment screening hits. In this study, we first find a novel and specific inhibitor of OptrA (CP1), which suppressed the ATPase activity of OptrA in vitro by 30%. A hydrogen bond formed between the 8‐position phenylcyclic cyano group in CP1 and the amino acid residue Lys‐271 allows CP1 to form a stable complex with OptrA protein. These findings provide a theoretical basis for the further optimization of the inhibitor structure to obtain inhibitors with higher efficiencies.     

Conversion of 2,6-diamino-9-(2-hydroxyethoxymethyl)purine to acyclovir as catalyzed by adenosine deaminase

Adenosine deaminase (ADA) was partially purified from several sources using affinity chromatography. These enzymes have the capacity to catalyze the deamination of 2,6-diamino-9-(2-hydroxyethoxymethyl)purine (A134U) to form the antiviral agent acyclovir [9-(2-hydroxyethoxymethyl)guanine]. Their relative substrate efficiencies (Vmax/Km) with A134U (standardized to adenosine = 100) were: dog ADA, 0.092; human ADA, 0.015-0.029; rat ADA, 0.025; calf ADA, 0.016; and Escherichia coli ADA, 0.0003. In addition to having the lowest efficiency with A134U, the bacterial ADA was also distinguished by its lack of binding of the mammalian ADA inhibitor erythro-9-(2-hydroxy-3-nonyl)adenine and by its weak binding to the 9-(p-aminobenzyl)adenine-agarose affinity column. Four minor metabolites of A134U and acyclovir have been reported to be produced in the rat. These compounds are oxidized on either the C-8 position of the ring or the terminal carbon of the side chain. Neither acyclovir nor any of these metabolites produced significant inhibition of calf intestine ADA. The oxidized metabolites containing an N-6 amino group were extremely slow substrates of this enzyme.     

Synthesis, antiproliferative, and antiviral activity of certain 4-aminopyrrolo[2,3-d]pyridazine nucleosides: an entry into a novel series of adenosine analogues.

The preparation of novel heterocyclic base modified adenosine analogues, the 4-aminopyrrolo[2,3-d]pyridazine nucleosides, is described. Crucial to their successful preparation was the use of the pyrrole glycoside intermediates 3-cyano-2-formyl-1-(2,3,5-tri-O-benzyl-beta-D-ribofuranosyl)pyrrole (11) and 3-cyano-2-formyl-1-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl)pyrrole (17). Treatment of 11 and 17 with hydrazine dihydrochloride followed by treatment with boron trichloride provided 4-amino-1-beta-D-ribofuranosylpyrrolo[2,3-d]pyridazine (2) and 4-amino-1-beta-D-arabinofuranosylpyrrolo[2,3-d]pyridazine (3), respectively. 4-Amino-3-bromo-1-beta-D-ribofuranosylpyrrolo[2,3-d]-pyridazine (4) was prepared by a bromination of 4-amino-1-(2,3,5-tri-O-benzyl-beta-D-ribofuranosyl)pyrrolo[2,3-d]pyri daz ine (12) and subsequent removal of the benzyl groups with boron trichloride. Compounds 2-4 were evaluated for antiproliferative and antiviral activity. The tubercidin analogue (2) and its arabinosyl derivative (3) were virtually inactive in all assays. In contrast, the 3-bromo analogue 4 inhibited growth of L1210 and H. Ep. 2 cells. Compound 4 was also active against human cytomegalovirus and herpes simplex virus type 1, but the antiviral activity was not completely separated from cytotoxicity.