A novel inhibitor of vacuolar ATPase, FR167356, which can discriminate between osteoclast vacuolar ATPase and lysosomal vacuolar ATPase

1 Vacuolar ATPase (V-ATPase) has been proposed as a drug target in lytic bone diseases. Studies of bafilomycin derivatives suggest that the key issue regarding the therapeutic usefulness of V-ATPase inhibitors is selective inhibition of osteoclast V-ATPase. Previous efforts to develop therapeutic inhibitors of osteoclast V-ATPase have been frustrated by a lack of synthetically tractable and biologically selective leads. Therefore, we tried to find novel potent and specific V-ATPase inhibitors, which have new structural features and inhibition selectivity, from random screening using osteoclast microsomes. Finally, a novel V-ATPase inhibitor, FR167356, was obtained through chemical modification of a parental hit compound. 2 FR167356 inhibited not only H+ transport activity of osteoclast V-ATPase but also H+ extrusion from cytoplasm of osteoclasts, which depends on the V-ATPase activity. As expected, FR167356 remarkably inhibited bone resorption in vitro. 3 FR167356 also showed inhibitory effects on other V-ATPases, renal brush border V-ATPase, macrophage microsome V-ATPase and lysosomal V-ATPase. However, FR167356 was approximately seven-fold less potent in inhibiting lysosomal V-ATPase compared to osteoclast V-ATPase. Moreover, LDL metabolism in cells, which depends on acidification of lysosome, was blocked merely at higher concentration than bone resorption, suggesting that FR167356 inhibits V-ATPase of osteoclast ruffled border membrane still more selectively than lysosome at the cellular level. 4 These results from the experiments seem to indicate that osteoclast V-ATPase may be different from lysosomal V-ATPase in respect of their structure. 5 FR167356 had a novel chemical structural feature as well as inhibitory characteristics distinctly different from any previously known V-ATPase inhibitor family. Therefore, FR167356 is thought to be a useful tool for estimating the essential characteristics of V-ATPase inhibitors for drug development.     

海洋天然产物brevianamide K的全合成

摘 要：目的 对海洋曲霉菌的次级代谢产物brevianamide K进行全合成研究,旨在解决其天然来源有限的问题,进而为其生物活性、作用机制的进一步研究以及同家族其他化合物的合成奠定基础。方法 以N-Pht-甘氨酸为起始原料,通过酰化、去保护、胺酯交换、乙酰基保护反应得到羟醛缩合反应的1个片段。以吲哚为起始原料,通过氯代、取代、Vilsmeier-Haack反应、保护基保护得到另1个片段。2个片段发生羟醛缩合反应后脱除保护基完成目标分子的全合成。结果 从商业可得化合物出发,通过最长线性7步反应,以9%的总收率完成brevianamide K的首次全合成,为后续活性研究和同家族其他化合物的合成奠定了基础。关键词：brevianamide K;吲哚二酮哌嗪生物碱;羟醛缩合     

微生物天然产物生物及化学信息学最新进展

摘要：微生物天然产物一直是药物开发的重要源泉,而且目前仍是新结构天然产物的重要来源。但随着微生物天然产物基数的增加,重复发现已经成为制约其发展的主要因素,而基于生物信息学和化学信息学建立起来的基因组挖掘技术是解决这一问题的关键。近年来天然产物相关信息学研究一直处于加速发展阶段,为了使天然产物研究者能够及时了解并选择性使用这些信息学工具,以提高新化合物的发现效率,本文对近两年来微生物天然产物研究领域相关的信息学工具进行了综述。     

Bcl-2蛋白天然产物抑制剂的研究进展

研究表明Bcl-2蛋白过度表达会阻止正常的细胞凋亡,是肿瘤产生及发生耐药的重要原因之一.近几年,其抗肿瘤小分子抑制剂的研究逐渐成为热点.研究者发现了一些不同结构类型的抑制剂,其中天然产物占很大比重.文中对已发现的Bcl-2蛋白天然产物抑制剂(包括棉酚、红桔酚、茶多酚、抗菌霉素A3)的结构、生物活性、与蛋白结合模式及结构改造等方面进行了系统的综述,着重介绍了几类经结构改造后活性较好的棉酚衍生物(ApoGossypol,Tw37,TM-1206,BI-33),期望对从天然产物中寻找Bcl-2抑制剂以及合理设计抑制剂提供帮助.     

Synthesis, activity, and molecular modeling studies of novel human aldose reductase inhibitors based on a marine natural product

Aldose reductase (ALR2) has been implicated in the etiology of diabetic complications, including blindness. Because of the limited number of currently available drugs for the prevention of these long-term complications, the discovery of new ALR2 inhibitors appears highly desirable. In this study, a polybrominated diphenyl ether (1) naturally occurring in a marine sponge was found to inhibit recombinant human ALR2 with an IC(50) of 6.4 microM. A series of polyhalogenated analogues that were synthesized and tested in vitro to explore the structure-activity relationships displayed various degrees of inhibitory activity. The most active compounds were also capable of preventing sorbitol accumulation inside human retinal cells. In this cell-based assay, the most potent synthesized analogue (16) showed a 17-fold increase in inhibitory activity compared to that of sorbinil (IC(50) = 0.24 vs 4 microM). A molecular representation of human ALR2 in complex with the natural product was built using homology modeling, automated docking, and energy refinement methods. AMBER parameters for the halogen atoms were derived and calibrated using condensed phase molecular dynamics simulations of fluorobenzene, chlorobenzene, and bromobenzene. Inhibitor binding is proposed to cause a conformational change similar to that recently reported for zenarestat. A free energy perturbation thermodynamic cycle allowed us to assess the importance of a crucial bromine atom that distinguishes the active lead compound from a much less active close natural analogue. Remarkably, the spatial location of this bromine atom is equivalent to that occupied by the only bromine atom present in zenarestat.     

Antiviral and anticancer optimization studies of the DNA-binding marine natural product aaptamine

Aaptamine has potent cytotoxicity that may be explained by its ability to intercalate DNA. Aaptamine was evaluated for its ability to bind to DNA to validate DNA binding as the primary mechanism of cytotoxicity. Based on UV-vis absorbance titration data, the K(obs) for aaptamine was 4.0 (+/-0.2) x 10(3) which was essentially equivalent to the known DNA intercalator N-[2-(diethylamino)ethyl]-9-aminoacridine-4-carboxamide. Semi-synthetic core modifications were performed to improve the general structural diversity of known aaptamine analogs and vary its absorption characteristics. Overall, 26 aaptamine derivatives were synthesized which consisted of a simple homologous range of mono and di-N-alkylations as well as some 9-O-sulfonylation and bis-O-isoaaptamine dimer products. Each product was evaluated for activity in a variety of whole cell and viral assays including a unique solid tumor disk diffusion assay. Details of aaptamine's DNA-binding activity and its derivatives' whole cell and viral assay results are discussed.     

Enhancing marine natural product structural diversity and bioactivity through semisynthesis and biocatalysis

In the last several decades the plants, animals and microbes from the marine environment have revealed a portion of what is clearly a tremendous resource for structurally diverse and bioactive secondary metabolites. Many of these extraordinarily sophisticated and bioactive natural products can be isolated in significant quantities without great difficulty. As a result these readily available bioactive natural products provide valuable starting materials for the rational generation of libraries of compounds prepared through semisynthesis and biocatalysis. A review of our work using marine natural products to generate rationally designed compound libraries and their biological activity against infectious diseases, cancer and neurological targets is presented. The marine natural products utilized to date as starting materials consist of compounds from a variety of structural classes and include: aureol, puupehenone, sarcophine, palinurin, and the manzamine alkaloids. The possibility to generate diverse bioactive products beginning with a marine natural product scaffold is a direct result of improvements made in the technologies to harvest samples from the ocean, purify and characterize complex natural products quickly and complete chemical reactions and biotransformations in parallel. As a result the vast resources of the ocean can now be utilized routinely to design and produce countless products to be evaluated as part of drug discovery and development programs.     

Intracellular sequestration of amiodarone: role of vacuolar ATPase and macroautophagic transition of the resulting vacuolar cytopathology

Background and purpose:

Tissue deposits of the anti-arrhythmic drug amiodarone are a major source of side effects (skin discoloration, etc.). We addressed the mechanism of the concentration of amiodarone in cells, and characterized the resulting vacuolar cytopathology and its evolution towards macroautophagy.

Experimental approach:

Sequestration of amiodarone in human cells (macrophages, smooth muscle cells, HEK 293a cells) was evaluated using its violet fluorescence and cytopathology using GFP-conjugated subcellular markers. Autophagic signalling was probed by immunoblotting for the effector protein LC3. A patient biopsy of amiodarone-induced blue-gray skin discoloration was investigated for the presence of macroautophagy (immunofluorescence for LC3).

Key results:

Most of the amiodarone (1–20 µM, 4–24 h) captured by cultured cells (macrophages were most avid) was present in enlarged vacuoles. The specific vacuolar ATPase (V-ATPase) inhibitors, bafilomycin A1 or {"type":"entrez-nucleotide","attrs":{"text":"FR167356","term_id":"258088392","term_text":"FR167356"}}FR167356, prevented vacuolization and drug uptake. Vacuoles in HEK 293a cells were positive for markers of late endosomes and lysosomes (GFP-Rab7, -CD63) and for an effector of macroautophagy, GFP-LC3. The vacuoles accumulated endogenous LC3 and filled with lipids (Nile red staining) following longer amiodarone treatments (≥24 h). The electrophoretic mobility of both GFP-LC3 and endogenous LC3 changed, showing activation in response to amiodarone. Paraffin tissue sections of the pigmented skin exhibited granular LC3 accumulation in superficial dermis macrophages.

Conclusion and implications:

Vacuolar sequestration of amiodarone occurs at concentrations close to therapeutic levels, is mediated by V-ATPase and evolves towards persistent macroautophagy and phospholipidosis. This cytopathology is not cell type specific, but tissue macrophages appear to be particularly susceptible.     

Strongylophorines: natural product inhibitors of hypoxia-inducible factor-1 transcriptional pathway

Rapidly increasing experimental and clinical data provides evidence for the role of hypoxia inducible factor-1 (HIF-1) as a crucial mediator of tumor survival and progression. In our effort to identify inhibitors of the HIF-1 activation pathway, we screened fractions from marine invertebrates. Fractions from an extract of Petrosia (Strongylophora) strongylata potently inhibited the HIF-1 activation pathway. Strongylophorines 2, 3, and 8 isolated from the active fractions were found to be responsible for the HIF-1 inhibition with EC 50 values of 8, 13, and 6 microM, respectively.     

基于海洋天然产物oroidin的结构修饰及其衍生物的抑菌活性研究

目的 针对海洋天然产物oroidin进行衍生物的合成以及抑菌活性评价。 方法 以吡咯-2-羧酸为起始原料,经过卤素取代、酰胺缩合、还原胺化等反应,四步合成oroidin类似物,并对衍生物进行抑菌活性评价。 结果 总计合成了20个衍生物,通过抑菌活性测试,发现了对多种菌株如枯草芽孢杆菌、草分枝杆菌、大肠杆菌等有抑制活性的化合物,其中化合物21和24对枯草芽孢杆菌的MIC值都达到3.125 μmol?L?1。该类化合物可应用于抗菌药物的开发。     

海洋天然产物Polycarpaurines C的合成及其对新型冠状病毒SARS-CoV-2的抑制作用

摘 要：目的：合成海洋天然产物,含硫海洋生物碱Polycarpaurines C,并测试其对SARS-CoV-2的抑制作用。方法：将4-乙酰基苯硼酸为原料经过过氧化氢氧化、甲基化、溴化、引入甲胺基、与2-乙基异硫脲氢溴酸盐缩合、与S2Cl2氧化偶联等反应,经过7步合成Polycarpaurines C,并对其测试对于SARS-CoV-2的抑制作用,利用分子对接技术测试Polycarpaurines C与Mpro的结合。结果：合成了目标天然产物Polycarpaurines C,并对其测试了对SARS-CoV-2的抑制作用,结果显示Polycarpaurine C对SARS-CoV-2具有不错的抑制作用,测得IC50为13.76 μM,但是与阳性药还有一定的差距,可作为药物进一步开发的模板骨架。     

Cardiovascular & Renal Novel CETP inhibitors isolated from marine sponge

Claims related to the discovery of new antifungal agents and methods to improve existing marketed drugs dominate the patent literature dating from June 1995 to June 1997. The bulk of this review deals with entries that involve the synthesis and evaluation of new compounds and novel analogues of known classes of antifungals. Coverage related to the development of combination therapies and the use of formulation vehicles to improve the physicochemical properties, pharmacokinetics and toxicity profiles associated with parent compounds is also included.     

海洋天然产物geodin系列衍生物的细胞毒活性评价及构效关系初步研究(英文）

摘 要：目的 目前癌症仍然是威胁人类健康的恶性疾病之一,临床使用的传统药物通常受到耐药性和副作用的限制,因此寻找新型高效的抗癌药物迫在眉睫。对具有grisan 骨架的海洋天然产物geodin (1) 及其衍生物（2?26）进行了细胞毒活性评价,并探究了其初步构效关系。方法 采用MTT法,用人非小细胞肺癌细胞系A549和人肝癌细胞系HepG2、Bel-7402对geodin (1) 及其衍生物（2?26）进行了细胞毒活性评价。结果 对Geodin 的4-OH修饰后得到的衍生物中,化合物2?4, 6, 7, 9?18和20?25表现出强到中等程度的细胞毒活性,IC50值在0.81 ~ 4.78 μM之间。特别是化合物16,对A549和HepG2细胞表现出强效的细胞毒活性,其IC50值分别为0.86和0.81 μM。结论 化合物16是一种潜在的抗癌先导化合物。     

Novel tyrosinase inhibitors from natural resources - their computational studies

Tyrosinase is a multi-copper enzyme widely distributed in different organisms, including plants & mammals, etc., which is responsible for pigmentations, undesired browning of fruits and vegetables. This is the key enzyme in the melanogenesis in human and molting process of insects. Therefore the inhibitors of the enzyme may lead to novel skin whitening agents, anti-browning substances or compounds for insect control. A large numbers of moderate to potent tyrosinase inhibitors have been reported during the last decade. From our group, we reported a number of potent inhibitors from synthetic, semi-synthetic and natural origins. The compounds are from several chemical classes, like phenolics, terpenes, steroids, chalcones, flavonoids, alkaloids, long-chain fatty acids, coumarins, sildenafil analogs, bipiperidines, biscoumarins, oxadiazole, tetraketones, etc. More recently, the crystal structure of mushroom and couple of other tyrosinases has been published and more recently the crystal structure of mushroom tyrosinase complexes with a highly potent inhibitor tropolone has been reported. Yet there is a lack of information of inhibitor-tyrosinase intermolecular interactions. To overcome such issues, some researchers started utilizing in silico tools, like molecular docking simulations, for such purposes. There are also few papers published about the successful utilization of computational tools like QSAR-based and ligand-based virtual screening to identify novel and potent inhibitors of the enzyme. In our group, we are using all possible computational tools, like ligand-based as well structure-based approaches, to identify new inhibitors. In this review, some of such examples are briefly described.     

Vaporization,bioactive formulations and a marine natural product: different perspectives on antivirals

This note examines three aspects of antivirals as they can potentially relate to the treatment of COVID-19; (i) the use of vaporization for the delivery of antivirals, with the bulk constituents having mild antiviral efficacy, (ii) a counter intuitive approach to formulation that, is in part, based on delivering multiple species that fall into three categories; building blocks for the virus to accelerate replication; an energy source for the infected cell to boast its immune response; species that antagonize or provide toxicity to the virus, (iii) the application of a marine natural product extract with several species, as opposed to a focusing on a single molecule as the anti-viral agent.

1. Download : Download high-res image (122KB)
2. Download : Download full-size image