Synthesis of Marine Natural Products and Analogues

A special issue of Marine Drugs (ISSN 1660-3397).

Deadline for manuscript submissions: closed (31 October 2019) | Viewed by 15738

Special Issue Editor

Special Issue Information

Dear Colleagues,

Marine natural products are generally characterized by high chemical diversity, biochemical specificity and other molecular properties that make them favorable as lead structures for drug discovery. In this field one of the main problems is often the reduced natural availability of the isolated substances that can make complicated both the structural characterization and possible future developments. For these reasons, the study of bioactive marine metabolites should rely on the development of chemical synthesis and synthetic strategies aimed at preparation of pure compounds and analogs both for structural confirmation and/or for the large-scale preparation necessary for future applications.

This Special Issue aims to collect original research articles regarding new synthetic strategies for secondary marine metabolites that can favor applications of these molecules and/or can solve structural challenges common in the field of natural substances.

Dr. Emiliano Manzo
Guest Editor

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Keywords

  • natural products
  • marine products
  • secondary metabolites
  • synthesis
  • synthetic strategies
  • drug discovery

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Published Papers (4 papers)

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Research

17 pages, 3006 KiB  
Article
A Study for the Access to a Semi-synthetic Regioisomer of Natural Fucosylated Chondroitin Sulfate with Fucosyl Branches on N-acetyl-Galactosamine Units
by Giulia Vessella, Serena Traboni, Anna V. A. Pirozzi, Antonio Laezza, Alfonso Iadonisi, Chiara Schiraldi and Emiliano Bedini
Mar. Drugs 2019, 17(12), 655; https://doi.org/10.3390/md17120655 - 21 Nov 2019
Cited by 12 | Viewed by 2964
Abstract
Fucosylated chondroitin sulfate (fCS) is a glycosaminoglycan found up to now exclusively in the body wall of sea cucumbers. It shows several interesting activities, with the anticoagulant and antithrombotic as the most attractive ones. Its different mechanism of action on the blood coagulation [...] Read more.
Fucosylated chondroitin sulfate (fCS) is a glycosaminoglycan found up to now exclusively in the body wall of sea cucumbers. It shows several interesting activities, with the anticoagulant and antithrombotic as the most attractive ones. Its different mechanism of action on the blood coagulation cascade with respect to heparin and the retention of its activity by oral administration make fCS a very promising anticoagulant drug candidate for heparin replacement. Nonetheless, its typically heterogeneous structure, the detection of some adverse effects and the preference for new drugs not sourced from animal tissues, explain how mandatory is to open an access to safer and less heterogeneous non-natural fCS species. Here we contribute to this aim by investigating a suitable chemical strategy to obtain a regioisomer of the natural fCS polysaccharide, with sulfated l-fucosyl branches placed at position O-6 of N-acetyl-d-galactosamine (GalNAc) units instead of O-3 of d-glucuronic acid (GlcA) ones, as in natural fCSs. This strategy is based on the structural modification of a microbial sourced chondroitin polysaccharide by regioselective insertion of fucosyl branches and sulfate groups on its polymeric structure. A preliminary in vitro evaluation of the anticoagulant activity of three of such semi-synthetic fCS analogues is also reported. Full article
(This article belongs to the Special Issue Synthesis of Marine Natural Products and Analogues)
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13 pages, 1048 KiB  
Article
Synthesis and Preliminary Biological Evaluation of Two Fluoroolefin Analogs of Largazole Inspired by the Structural Similarity of the Side Chain Unit in Psammaplin A
by Bingbing Zhang, Guangsheng Shan, Yinying Zheng, Xiaolin Yu, Zhu-Wei Ruan, Yang Li and Xinsheng Lei
Mar. Drugs 2019, 17(6), 333; https://doi.org/10.3390/md17060333 - 3 Jun 2019
Cited by 7 | Viewed by 3262
Abstract
Largazole, isolated from a marine Cyanobacterium of the genus Symploca, is a potent and selective Class I HDAC (histone deacetylation enzymes) inhibitor. This natural 16-membered macrocyclic depsipeptide features an interesting side chain unit, namely 3-hydroxy-7-mercaptohept-4-enoic acid, which occurs in many other natural [...] Read more.
Largazole, isolated from a marine Cyanobacterium of the genus Symploca, is a potent and selective Class I HDAC (histone deacetylation enzymes) inhibitor. This natural 16-membered macrocyclic depsipeptide features an interesting side chain unit, namely 3-hydroxy-7-mercaptohept-4-enoic acid, which occurs in many other natural sulfur-containing HDAC inhibitors. Notably, one similar fragment, where the amide moiety replaces the trans alkene moiety, appears in Psammaplin A, another marine natural product with potent HDAC inhibitory activities. Inspired by such a structural similarity, we hypothesized the fluoroolefin moiety would mimic both the alkene moiety in Largazole and the amide moiety in Psammaplin A, and thus designed and synthesized two novel fluoro olefin analogs of Largazole. The preliminary biological assays showed that the fluoro analogs possessed comparable Class I HDAC inhibitory effects, indicating that this kind of modification on the side chain of Largazole was tolerable. Full article
(This article belongs to the Special Issue Synthesis of Marine Natural Products and Analogues)
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15 pages, 3223 KiB  
Article
New 1,2,4-Oxadiazole Nortopsentin Derivatives with Cytotoxic Activity
by Stella Cascioferro, Alessandro Attanzio, Veronica Di Sarno, Simona Musella, Luisa Tesoriere, Girolamo Cirrincione, Patrizia Diana and Barbara Parrino
Mar. Drugs 2019, 17(1), 35; https://doi.org/10.3390/md17010035 - 8 Jan 2019
Cited by 56 | Viewed by 4188
Abstract
New analogs of nortopsentin, a natural 2,4-bis(3′-indolyl)imidazole alkaloid, in which the central imidazole ring of the natural lead was replaced by a 1,2,4-oxadiazole moiety, and in which a 7-azaindole portion substituted the original indole moiety, were efficiently synthesized. Among all derivatives, prescreened against [...] Read more.
New analogs of nortopsentin, a natural 2,4-bis(3′-indolyl)imidazole alkaloid, in which the central imidazole ring of the natural lead was replaced by a 1,2,4-oxadiazole moiety, and in which a 7-azaindole portion substituted the original indole moiety, were efficiently synthesized. Among all derivatives, prescreened against the HCT-116 colon rectal carcinoma cell line, the two most active compounds were selected and further investigated in different human tumor cells showing IC50 values in the micromolar and submicromolar range. Flow cytometric analysis of propidium iodide-stained MCF-7 cells demonstrated that both the active derivatives caused cell cycle arrest in the G0–G1 phase. The cell death mechanism induced by the compounds was considered to be apoptotic by measuring the exposure of phosphatidylserine to the outer membrane and observed morphological evaluation using acridine orange/ethidium bromide double staining. Moreover, further tested on intestinal normal-like differentiated Caco-2 cell line, they exhibited preferential toxicity towards cancer cells. Full article
(This article belongs to the Special Issue Synthesis of Marine Natural Products and Analogues)
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12 pages, 2681 KiB  
Article
Synthesis of Pseudellone Analogs and Characterization as Novel T-type Calcium Channel Blockers
by Dan Wang, Pratik Neupane, Lotten Ragnarsson, Robert J. Capon and Richard J. Lewis
Mar. Drugs 2018, 16(12), 475; https://doi.org/10.3390/md16120475 - 28 Nov 2018
Cited by 8 | Viewed by 4568
Abstract
T-type calcium channel (CaV3.x) blockers are receiving increasing attention as potential therapeutics for the treatment of pathophysiological disorders and diseases, including absence epilepsy, Parkinson’s disease (PD), hypertension, cardiovascular diseases, cancers, and pain. However, few clinically approved CaV3.x blockers are [...] Read more.
T-type calcium channel (CaV3.x) blockers are receiving increasing attention as potential therapeutics for the treatment of pathophysiological disorders and diseases, including absence epilepsy, Parkinson’s disease (PD), hypertension, cardiovascular diseases, cancers, and pain. However, few clinically approved CaV3.x blockers are available, and selective pharmacological tools are needed to further unravel the roles of individual CaV3.x subtypes. In this work, through an efficient synthetic route to the marine fungal product pseudellone C, we obtained bisindole alkaloid analogs of pseudellone C with a modified tryptophan moiety and identified two CaV3.2 (2, IC50 = 18.24 µM; 3, IC50 = 6.59 µM) and CaV3.3 (2, IC50 = 7.71 µM; 3, IC50 = 3.81 µM) selective blockers using a FLIPR cell-based assay measuring CaV3.x window currents. Further characterization by whole-cell patch-clamp revealed a preferential block of CaV3.1 activated current (2, IC50 = 5.60 µM; 3, IC50 = 9.91 µM), suggesting their state-dependent block is subtype specific. Full article
(This article belongs to the Special Issue Synthesis of Marine Natural Products and Analogues)
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