Design and Synthesis of C-1 Methoxycarbonyl Derivative of Narciclasine and Its Biological Activity

A 15-step chemoenzymatic total synthesis of C-1 methoxycarbonyl narciclasine (10) was accomplished. The synthesis began with the toluene dioxygenase-mediated dihydroxylation of ortho-dibromobenzene to provide the corresponding cis-dihydrodiol (12) as a single enantiomer. Further key steps included a nitroso Diels–Alder reaction and an intramolecular Heck cyclization. The C-1 homolog 10 was tested and evaluated for antiproliferative activity against natural narciclasine (1) as the positive control. Experimental and spectral data are reported for all novel compounds.     

Chemistry of the Benzotropone Endoperoxides and Their Conversion into Tropolone Derivatives: Unusual Endoperoxide Rearrangements

The chemistry of two bicyclic endoperoxides, obtained by photooxygenation of 2,3‐benzotropone (=5H‐benzocyclohepten‐5‐one; 5 ) and of its ethyl carboxylate derivative 15 , was investigated with the aim of synthesizing the respective benzotropolone derivatives. The reaction of the endoperoxide 10 derived from 5 with thiourea gave the desired benzotropolone, i.e., 6‐hydroxy‐5H‐benzocyclohepten‐5‐one ( 11 ), in high yield (Scheme 1). On the other hand, the endoperoxide 16 derived from the ethyl carboxylate derivative 15 underwent an unprecedented transformation yielding mainly the ring‐contracted lactones 28 and 29 besides the expected substituted benzotropolone derivative 27 (Scheme 5). However, the thermolysis reaction of the same endoperoxide 16 resulted in the formation of four rearranged compounds with different skeletons (Scheme 3). The formation mechanism of all products is discussed (Schemes 4 and 6).     

Advances in the Chemical and Biological Characterization of Amaryllidaceae Alkaloids and Natural Analogues Isolated in the Last Decade

Amaryllidaceae are bulbous wild and cultivated plants well known for their beautiful flowers and pharmaceutical applications, essentially due to the alkaloids and flavonoids content. Hundreds of alkaloids have been isolated until now and several scientific publications reported their sources, chemical structures, and biological activities. During the last decade, some unstudied Amaryllidaceae plants were the object of in-depth investigations to isolate and chemically and biologically characterize new and already known alkaloids as well as some analogues. This review describes the isolation and chemical and biological characterization of the Amaryllidaceae alkaloids, and their analogues obtained in the last decade, focusing the discussion on the new ones.     

Short Overview of Some Assays for the Measurement of Antioxidant Activity of Natural Products and Their Relevance in Dermatology

Impaired systemic redox homeostasis is implicated in the onset and development of various diseases, including skin diseases. Therefore, continuous search for natural products with antioxidant bioactivities applicable in biomedicine is attractive topic of general interest. Research efforts aiming to validate antioxidant potentials of natural products has led to the development of several assays based on various test principles. Hence, understanding the advantages and limitations of various assays is important for selection of assays useful to study antioxidant and related bioactivities of natural products of biomedical interest. This review paper gives a short overview on some chemical and cellular bioassays used to estimate the antioxidant activity of chosen natural products together with a brief overview on the use of natural products with antioxidant activities as adjuvant medicinal remedies in dermatology.     

Bioactivity-Directed Fractionation of Alkaloids from Some Amaryllidaceae Plants and Their Anticholinesterase Activity

Chloroform:methanol extracts of the bulbs of five Amaryllidaceae plants, namely Galanthus elwesii Hooker fil., G. Ikariae L., Narcissus tazetta subsp. tazetta L., Leucojum aestivum L., and Pancratium maritimum L. growing in Turkey, were evaluated for their anticholinesterase activity by the Ellman method in comparison with galanthamine as the standard drug. Bioactivity-directed fractionation and isolation studies carried out on G. ikariae and N. tazetta subsp. tazetta extracts afforded eight Amaryllidaceae-type alkaloids in total. We found that the activity of both plant extracts was due to the synergistic interaction of the alkaloids isolated.     

氮杂香豆雌酚衍生物的合成及其抗肿瘤活性

以间苯二甲醚为原料, 经碘代、偶联、胺解、分子内环化及脱甲醚环化共5步反应,合成9个氮杂香豆雌酚衍生物（6a~6i）, 其结构经¹H NMR, ¹³C NMR 和APCI-MS表征。采用MTT法研究了6对Hela、 SKOV3、 BEL-7404、 HepG2及A-549等癌细胞的体外生长抑制活性。结果表明：6h对SKOV3细胞的生长抑制活性最高,其IC₅₀值为81.58 μmol·L^-1。     

Anticancer Activities of Marine-Derived Phenolic Compounds and Their Derivatives

Since the middle of the last century, marine organisms have been identified as producers of chemically and biologically diverse secondary metabolites which have exerted various biological activities including anticancer, anti-inflammatory, antioxidant, antimicrobial, antifouling and others. This review primarily focuses on the marine phenolic compounds and their derivatives with potent anticancer activity, isolated and/or modified in the last decade. Reports on the elucidation of their structures as well as biosynthetic studies and total synthesis are also covered. Presented phenolic compounds inhibited cancer cells proliferation or migration, at sub-micromolar or nanomolar concentrations (lamellarins D (37), M (38), K (39), aspergiolide B (41), fradimycin B (62), makulavamine J (66), mayamycin (69), N-acetyl-N-demethylmayamycin (70) or norhierridin B (75)). In addition, they exhibited anticancer properties by a diverse biological mechanism including induction of apoptosis or inhibition of cell migration and invasive potential. Finally, phlorotannins 1–7 and bromophenols 12–29 represent the most researched phenolic compounds, of which the former are recognized as protective agents against UVB or gamma radiation-induced skin damages. Finally, phenolic metabolites were assorted into six main classes: phlorotannins, bromophenols, flavonoids, coumarins, terpenophenolics, quinones and hydroquinones. The derivatives that could not be attributed to any of the above-mentioned classes were grouped in a separate class named miscellaneous compounds.     

用组合化学建立天然产物类似物库

天然产物是药物先导化合物的重要来源.组合化学技术在天然产物的研究中起着越来越重要的作用.目前已构建并合成了许多以天然产物为模板的化合物库,为基于天然产物的药物研究开辟了广阔的空间.     

Chemistry and biology of roseophilin and the prodigiosin alkaloids: a survey of the last 2500 years

The pyrrole alkaloids of the prodigiosin family make up an unusual chapter in the chemistry of natural products. Owing to the characteristic red color of these secondary metabolites, colonies of the Gram-negative-producing bacteria may strikingly resemble droplets of blood. This phenomenon caused considerable confusion in the past and was likely responsible for many seemingly miraculous (prodigious) events. After the eventual transition from superstition to science, the prodigiosins started to attract considerable attention because of their promising physiological properties. Most interesting are the immunosuppressive activities at doses that are not cytotoxic, in particular since in vivo studies suggest that the prodigiosins act synergistically with cyclosporine A or FK 506, which are presently the dominant drugs in clinical immunosuppressive regimens. Furthermore, the chemistry of the closely related and structurally rather unique alkaloid roseophilin is summarized, a cytotoxic agent that recently became the focal point of many innovative total syntheses.     

Synthesis of All Stereoisomers of Monomeric Spectomycin A1/A2 and Evaluation of Their Protein SUMOylation-Inhibitory Activity

A synthetic methodology to access all possible stereoisomers of spectomycin A1 (SMA1) and A2 (SMA2) has been established through late-stage diversification. The key reaction for the construction of all four diastereomers is an intramolecular cyclization based on the umpolung of π-allyl palladium species with bis(pinacolato)diborane (B₂(pin)₂). Silyl group assisted direct benzylic oxidation of each isomer enabled construction of the fragile β-hydroxytetralone skeleton to provide the SMAs. The relative and absolute stereochemistry of SMA2 was also determined, and the absolute stereochemistry of SMA1 was extrapolated based on the optical rotation of SMA2. The axial chirality of SMAs is discussed based on circular dichroism spectra and DFT calculations, and it is concluded that the M isomer is predominant in solution. Biochemical assessment of all isomers in vitro revealed that the C9 hydroxyl group and dimeric structure were both important for protein SUMOylation-inhibitory activity.     

Discovery and Total Synthesis of Natural Cystobactamid Derivatives with Superior Activity against Gram‐Negative Pathogens

Antibiotic discovery and development is challenging as chemical scaffolds of synthetic origin often lack the required pharmaceutical properties, and the discovery of novel ones from natural sources is tedious. Herein, we report the discovery of new cystobactamids with a significantly improved antibacterial profile in a detailed screening of myxobacterial producer strains. Some of these new derivatives display antibacterial activities in the low‐μg mL⁻¹ range against Gram‐negative pathogens, including clinical isolates of Klebsiella oxytoca, Pseudomonas aeruginosa, and fluoroquinolone‐resistant Enterobacteriaceae, which were not observed for previously reported cystobactamids. Our findings provide structure–activity relationships and show how pathogen resistance can be overcome by natural scaffold diversity. The most promising derivative 861‐2 was prepared by total synthesis, enabling further chemical optimization of this privileged scaffold.     

紫苏醇芳基钌配合物的合成及抗肿瘤性能

紫苏醇作为既有癌症预防又有癌症治疗作用的少数几种天然产物之一,曾作为临床药物用于癌症的治疗。但是紫苏醇通过口服给药生物利用度低、给药剂量大,因而限制了它的临床应用。我们将紫苏醇进行化学修饰,作为配体引入到芳基金属配合物中,合成了一种新型芳基钌配合物Ru-L,并利用核磁共振氢谱、碳谱、电喷雾质谱及元素分析对其进行了基础表征。配合物Ru-L对肿瘤细胞A2780、A2780/DDP及MCF-7都表现出较高的细胞毒活性,而对正常细胞株毒性较小(IC_(50)200μmol·L~(-1)),表明紫苏醇芳基钌配合物可以克服紫苏醇给药量大和毒性大等缺陷。紫外可见及荧光光谱表明配合物具有较快的水解速率,可通过嵌入作用与CT-DNA结合,并通过静态猝灭与BSA/HSA相互作用。流式细胞术也揭示配合物将肿瘤细胞周期阻滞在G0/G1期,从而导致了肿瘤细胞的凋亡。以上结果表明,基于紫苏醇的芳基钌配合物Ru-L克服了紫苏醇的高剂量、高毒性等缺点。     

Studies on Bioactive Selenium-containing Organophosphorus Compounds: Synthesis of 1-Aminoalkanephosphonate Derivatives of Benzisoselenazolone and Their Antitumor Activity

Various selenium-containing compounds are widely used as reagents and intermediates in organic synthesis.¹ In recent years biologically active organoselenium compounds have begun to attract considerable interest due to their unique and diverse potential pharmacological importance such as broad spectrum antitumor and antiviral activities, and some of them are even many times more active than their thio analogues.^2,3 It was found that benzisoselenazolones[e.g.,Ebselen, 2-phenyl-1,2-benzisoselenazol-3(2H)-one], are effective for the treatment of diseases caused by cell damage owing to increased formation of active oxygen metabolites⁴ and these pharmacological effects are mainly attributed to the glutathione peroxidase (GSH-Px) like properties.⁵     

6-取代喹唑啉衍生物的合成及抗肿瘤活性研究进展

喹唑啉及其衍生物作为重要的药效团,具有广谱的抗肿瘤生物活性,一直是药物化学研究的热点。本文围绕近年来6-酰胺类、卤代类、醚类、与7-位成环类、杂环类等喹唑啉衍生物的合成及其抗肿瘤活性作用机制研究进行概述,以期为活性更高、毒性更小的新型抗肿瘤化合物的设计合成提供参考。     

Synthesis and Antitumor Activity of 1-Substituted 1,2,3-Triazole-Mollugin Derivatives

A new series of mollugin-1,2,3-triazole derivatives were synthesized using a copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction of corresponding O-propargylated mollugin with aryl azides. All the compounds were evaluated for their cytotoxicity on five human cancer cell lines (HL-60, A549, SMMC-7721, SW480, and MCF-7) using MTS assays. Among the synthesized series, most of them showed cytotoxicity and most of all, compounds 14 and 17 exhibited significant cytotoxicity of all five cancer cell lines.     

化学发光法测定几种天然产物的抗自由基活性

为从天然产物中筛选出具有较好抗自由基活性的药物,利用鲁米诺 H2O2 CuSO4化学发光体系,测定了几种天然产物的抗自由基活性.结果表明抗自由基活性顺序为速溶茶>玉米须水提物>大豆异黄酮>Vc>刺槐花>花生壳丙酮提取物>玉米须醇提取物≈怀山药醇提物.     

6-氯-4-哌嗪基喹唑啉缩氨基硫脲类化合物的合成及体外抗肿瘤活性

以5-氯-2-氨基苯甲酸和甲酰胺为起始原料,经环化、氯化、取代和缩合反应,合成了3个未见文献报道的含哌嗪的喹唑啉衍生物5a~5c。 其结构用1H NMR、13C NMR、ESI-MS及IR测试技术进行了表征。 采用MTT法测试了化合物5a~5c对人胃癌SGC-7901、人口腔表皮样癌KB和人纤维肉瘤HT-1080的体外抗肿瘤活性。 结果表明,化合物5a~5c对人胃癌SGC-7901和人纤维肉瘤HT-1080有弱的抑制活性,而对人口腔表皮样癌KB无明显抑制活性。