Synthesis of isogranulatimide analogues possessing a pyrrole moiety instead of an imidazole heterocycle

Retracted Article: The synthesis and biological activity of marine alkaloid derivatives and analogues

The ocean is the origin of life, with a unique ecological environment, which has given birth to a wealth of marine organisms. The ocean is an important source of biological resources and tens of thousands of monomeric compounds have been separated from marine organisms using modern separation technology. Most of these monomeric compounds have some kind of biological activity that has attracted extensive attention from researchers. Marine alkaloids are a kind of compound that can be separated from marine organisms. They have complex and special chemical structures, but at the same time, they can show diversity in biological activities. The biological activities of marine alkaloids mainly manifest in the form of anti-tumor, anti-fungus, anti-viral, anti-malaria, and anti-osteoporosis properties. Many marine alkaloids have good medicinal prospects and can possibly be used as anti-tumor, anti-viral, and anti-fungal clinical drugs or as lead compounds. The limited amounts of marine alkaloids that can be obtained by separation, coupled with the high cytotoxicity and low selectivity of these lead compounds, has restricted the clinical research and industrial development of marine alkaloids. Marine alkaloid derivatives and analogues have been obtained via rational drug design and chemical synthesis, to make up for the shortcomings of marine alkaloids; this has become an urgent subject for research and development. This work systematically reviews the recent developments relating to marine alkaloid derivatives and analogues in the field of medical chemistry over the last 10 years (2010-2019). We divide marine alkaloid derivatives and analogues into five types from the point-of-view of biological activity and elaborated on these activities. We also briefly discuss the optimization process, chemical synthesis, biological activity evaluation, and structure-activity relationship (SAR) of each of these compounds. The abundant SAR data provides reasonable approaches for the design and development of new biologically active marine alkaloid derivatives and analogues.

Zn(OAc)2-catalyzed tandem cyclization of isocyanides, α-diazoketones, and anhydrides: a general route to polysubstituted maleimides

A zinc-catalyzed three-component reaction of isocyanides, α-diazoketones, and anhydrides has been realized as a novel and efficient method for the synthesis of polysubstituted maleimides.

Palladium-catalyzed aerobic oxidative carbonylation of alkynes with amines: a general access to substituted maleimides

A catalytic oxidative carbonylation reaction was developed for the synthesis of polysubstituted maleimides from alkynes and amines with air as a green oxidant.

Toward highly potent cancer agents by modulating the C-2 group of the arylthioindole class of tubulin polymerization inhibitors

New arylthioindole derivatives having different cyclic substituents at position 2 of the indole were synthesized as anticancer agents. Several compounds inhibited tubulin polymerization at submicromolar concentration and inhibited cell growth at low nanomolar concentrations. Compounds 18 and 57 were superior to the previously synthesized 5. Compound 18 was exceptionally potent as an inhibitor of cell growth: it showed IC₅₀ = 1.0 nM in MCF-7 cells, and it was uniformly active in the whole panel of cancer cells and superior to colchicine and combretastatin A-4. Compounds 18, 20, 55, and 57 were notably more potent than vinorelbine, vinblastine, and paclitaxel in the NCI/ADR-RES and Messa/Dx5 cell lines, which overexpress P-glycoprotein. Compounds 18 and 57 showed initial vascular disrupting effects in a tumor model of liver rhabdomyosarcomas at 15 mg/kg intravenous dosage. Derivative 18 showed water solubility and higher metabolic stability than 5 in human liver microsomes.

Synthesis and assignment of the absolute configuration of indenotryptoline bisindole alkaloid BE-54017

Synthesis of the indenotryptoline bisindole alkaloid, BE-54017, was accomplished using osmium-promoted cis-dihydroxylation of maleimide as a key step. After optical resolution, the absolute configuration of this molecule was determined by comparing its optical rotation and HPLC profile to those obtained for BE-54017 derived from enantiopure cladoniamide A, whose stereochemistry has been reported previously. BE-54017 with the correct absolute stereochemistry induced apoptosis of epidermal growth factor (EGF)-stimulated EGF receptor overexpressing A431 cells and inhibited vacuolar-type H(+)-ATPase (V-ATPase).

Design and synthesis of 2-heterocyclyl-3-arylthio-1H-indoles as potent tubulin polymerization and cell growth inhibitors with improved metabolic stability

New arylthioindoles (ATIs) were obtained by replacing the 2-alkoxycarbonyl group with a bioisosteric 5-membered heterocycle nucleus. The new ATIs 5, 8, and 10 inhibited tubulin polymerization, reduced cell growth of a panel of human transformed cell lines, and showed higher metabolic stability than the reference ester 3. These compounds induced mitotic arrest and apoptosis at a similar level as combretastatin A-4 and vinblastine and triggered caspase-3 expression in a significant fraction of cells in both p53-proficient and p53-defective cell lines. Importantly, ATIs 5, 8, and 10 were more effective than vinorelbine, vinblastine, and paclitaxel as growth inhibitors of the P-glycoprotein-overexpressing cell line NCI/ADR-RES. Compound 5 was shown to have medium metabolic stability in both human and mouse liver microsomes, in contrast to the rapidly degraded reference ester 3, and a pharmacokinetic profile in the mouse characterized by a low systemic clearance and excellent oral bioavailability.

Synthesis, checkpoint kinase 1 inhibitory properties and in vitro antiproliferative activities of new pyrrolocarbazoles

In the course of structure-activity relationship studies on granulatimide analogues, new pyrrolo[3,4-c]carbazoles have been synthesized in which the imidazole heterocycle was replaced by a five-membered ring lactam system or a dimethylcyclopentanedione. Moreover, the synthesis of an original structure in which a sugar moiety is attached to the indole nitrogen and to a six-membered D ring via an oxygen is reported. The inhibitory activities of the newly synthesized compounds toward checkpoint kinase 1 and their in vitro antiproliferative activities toward three tumor cell lines: murine leukemia L1210, and human colon carcinoma HT29 and HCT116 are described.

Synthesis, in vitro antiproliferative activities, and Chk1 inhibitory properties of pyrrolo[3,4-a]carbazole-1,3-diones, pyrrolo[3,4-c]carbazole-1,3-diones, and 2-aminopyridazino[3,4-a]pyrrolo[3,4-c]carbazole-1,3,4,7-tetraone

The synthesis of substituted pyrrolo[3,4-a]carbazole-1,3-diones, pyrrolo[3,4-c]carbazole-1,3-diones, and 2-aminopyridazino[3,4-a]pyrrolo[3,4-c]carbazole-1,3,4,7-tetraone is reported. Their inhibitory properties toward Checkpoint 1 kinase (Chk1) have been evaluated and their in vitro antiproliferative activities toward three tumor cell lines: murine leukemia L1210, human colon carcinoma HT29 and HCT116 have been determined. From the biological results, it appears that, in contrast with the upper E heterocycle, the lower D heterocycle is not absolutely required for Chk1 inhibition. The ATP binding pocket of Chk1 seems to be adaptable to substitution of the nitrogen of the imide E heterocycle with a hydroxymethyl group, allowing the fundamental hydrogen bond with the Glu(85) residue of the enzyme.

Bis-imide granulatimide analogues as potent Checkpoint 1 kinase inhibitors

Granulatimide and isogranulatimide, natural products isolated from an ascidian, were found to be abrogators of the cell cycle G2-M phase checkpoint by inhibition of Checkpoint 1 kinase (Chk1). In the course of structure-activity relationship studies on granulatimide analogues, we have synthesized a series of bis-imides, in which the imidazole moiety was replaced by an imide heterocycle. Various modifications have been introduced on one or both imide heterocycles, on the benzene ring, and on the indole nitrogen. Moreover, aza bis-imide analogues were synthesized in which the indole moiety was replaced by a 7-azaindole. Compared to those of granulatimide and isogranulatimide, the Chk1 inhibitory activities of some of the bis-imide carbazoles were stronger. In particular, 1,3,4,6-tetrahydro-10-hydroxy-7H-dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraone 11 exhibited an IC(50) value on purified full length Chk1 of 2 nM, which makes it a more potent Chk1 inhibitor than granulatimide and isogranulatimide. To get an insight into the selectivity of this new family of compounds, the inhibitory activities of 1,3,4,6-tetrahydro-7H-dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraone A have been evaluated on a panel of 15 kinases, the strongest inhibitory potency was found for Chk1. The inhibitory activities of compounds A, 5 and 11 toward Src tyrosine kinase and the cytotoxicity of various tumor cell lines were also evaluated.

Synthesis and biological evaluation of new dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraones, substituted with various saturated and unsaturated side chains via palladium catalyzed cross-coupling reactions

The syntheses of a series of dipyrrolo[3,4-a:3,4-c]carbazole-1,3,4,6-tetraones, substituted in 10-position with saturated and unsaturated side chains, via palladium catalyzed cross-coupling reactions, are described. These compounds can be considered as granulatimide bis-imide analogues. Their inhibitory activity toward Chk1 kinase and their antiproliferative activities in vitro in four tumor cell lines are reported.

Muscarine, imidazole, oxazole and thiazole alkaloids

Novel and structurally diverse natural products containing imidazol-, oxazole-, or thiazole-unit(s) display a wide variety of biological activities. The isolation, biological activity and total synthesis of naturally occurring muscarine, imidazole, oxazole and thiazole alkaloids have been reviewed. The literature covers from January 2003 to June 2004.