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17 pages, 2576 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

An Aminopyrimidone and Aminoimidazoles Alkaloids from the Rodrigues Calcareous Marine Sponge Ernsta naturalis

by Pierre-Eric Campos, Gaëtan Herbette, Laetitia Fougère, Patricia Clerc, Florent Tintillier, Nicole J. de Voogd, Géraldine Le Goff, Jamal Ouazzani and Anne Gauvin-Bialecki

Mar. Drugs 2022, 20(10), 637; https://doi.org/10.3390/md20100637 - 13 Oct 2022

Cited by 2 | Viewed by 2121

Abstract

A chemical study of the CH₂Cl₂−MeOH (1:1) extract from the sponge Ernsta naturalis collected in Rodrigues (Mauritius) based on a molecular networking dereplication strategy highlighted one novel aminopyrimidone alkaloid compound, ernstine A (1), seven new aminoimidazole alkaloid [...] Read more.

A chemical study of the CH₂Cl₂−MeOH (1:1) extract from the sponge Ernsta naturalis collected in Rodrigues (Mauritius) based on a molecular networking dereplication strategy highlighted one novel aminopyrimidone alkaloid compound, ernstine A (1), seven new aminoimidazole alkaloid compounds, phorbatopsins D–E (2, 3), calcaridine C (4), naamines H–I (5, 7), naamidines J–K (6, 8), along with the known thymidine (9). Their structures were established by spectroscopic analysis (1D and 2D NMR spectra and HRESIMS data). To improve the investigation of this unstudied calcareous marine sponge, a metabolomic study by molecular networking was conducted. The isolated molecules are distributed in two clusters of interest. Naamine and naamidine derivatives are grouped together with ernstine in the first cluster of twenty-three molecules. Phorbatopsin derivatives and calcaridine C are grouped together in a cluster of twenty-one molecules. Interpretation of the MS/MS spectra of other compounds of these clusters with structural features close to the isolated ones allowed us to propose a structural hypothesis for 16 compounds, 5 known and 11 potentially new. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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12 pages, 1532 KiB

Open AccessArticle

Seven New Alkaloids Isolated from Marine Flavobacterium Tenacibaculum discolor sv11

by Lei Wang, Michael Marner, Ute Mettal, Yang Liu and Till F. Schäberle

Mar. Drugs 2022, 20(10), 620; https://doi.org/10.3390/md20100620 - 30 Sep 2022

Cited by 4 | Viewed by 1777

Abstract

Marine flavobacterium Tenacibaculum discolor sv11 has been proven to be a promising producer of bioactive nitrogen-containing heterocycles. A chemical investigation of T. discolor sv11 revealed seven new heterocycles, including the six new imidazolium-containing alkaloids discolins C-H (1–6) and [...] Read more.

Marine flavobacterium Tenacibaculum discolor sv11 has been proven to be a promising producer of bioactive nitrogen-containing heterocycles. A chemical investigation of T. discolor sv11 revealed seven new heterocycles, including the six new imidazolium-containing alkaloids discolins C-H (1–6) and one pyridinium-containing alkaloid dispyridine A (7). The molecular structure of each compound was elucidated by analysis of NMR and HR-ESI-MS data. Furthermore, enzymatic decarboxylation of tryptophan and tyrosine to tryptamine and tyramine catalyzed by the decarboxylase DisA was investigated using in vivo and in vitro experiments. The antimicrobial activity of the isolated compounds (1–7) was evaluated. Discolin C and E (1 and 3) exhibited moderate activity against Gram-positive Bacillus subtilis DSM10, Mycobacterium smegmatis ATCC607, Listeria monocytogenes DSM20600 and Staphylococcus aureus ATCC25923, with MIC values ranging from 4 μg/mL to 32 μg/mL. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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10 pages, 8164 KiB

Open AccessArticle

A Series of New Pyrrole Alkaloids with ALR2 Inhibitory Activities from the Sponge Stylissa massa

by Qi Wang, Chunhua Gao, Zhun Wei, Xiaowen Tang, Lixia Ji, Xiangchao Luo, Xiaoping Peng, Gang Li and Hongxiang Lou

Mar. Drugs 2022, 20(7), 454; https://doi.org/10.3390/md20070454 - 12 Jul 2022

Cited by 5 | Viewed by 1625

Abstract

Twelve new and four known alkaloids including five different structural scaffolds were isolated from the sponge Stylissa massa collected in the South China Sea. Compound 1 is the first identified precursor metabolite of the classic 5/7/5 tricyclic skeleton with unesterified guanidine and carboxyl [...] Read more.

Twelve new and four known alkaloids including five different structural scaffolds were isolated from the sponge Stylissa massa collected in the South China Sea. Compound 1 is the first identified precursor metabolite of the classic 5/7/5 tricyclic skeleton with unesterified guanidine and carboxyl groups, compounds 2–5 and 13–15 belong to the spongiacidin-type pyrrole imidazole alkaloids (PIAs). Z- and E-configurations of the spongiacidin-type PIAs often appeared concomitantly and were distinguished by the chemical shift analysis of ¹³C NMR spectra. The structures of all twelve new compounds were determined by NMR, MS, and ECD analysis combined with single-crystal data of compounds 1, 5, and 10. In the aldose reductase (ALR2) inhibitory assay, six 5/7/5 tricyclic compounds (2–5, 13–15) displayed significant activities. Compounds 13 and 14, as the representative members of spongiacidin-PIAs, demonstrated their ALR2-targeted activities in SPR experiments with K_D values of 12.5 and 6.9 µM, respectively. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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9 pages, 1916 KiB

Open AccessCommunication

Unique Cyclized Thiolopyrrolones from the Marine-Derived Streptomyces sp. BTBU20218885

by Fuhang Song, Jiansen Hu, Xinwan Zhang, Wei Xu, Jinpeng Yang, Shaoyong Li and Xiuli Xu

Mar. Drugs 2022, 20(3), 214; https://doi.org/10.3390/md20030214 - 18 Mar 2022

Cited by 5 | Viewed by 2262

Abstract

Two new cyclized thiolopyrrolone derivatives, namely, thiolopyrrolone A (1) and 2,2-dioxidothiolutin (2), together with the kn own compound, thiolutin (3) were identified from a marine-derived Streptomyces sp. BTBU20218885, which was isolated from a mud sample collected from [...] Read more.

Two new cyclized thiolopyrrolone derivatives, namely, thiolopyrrolone A (1) and 2,2-dioxidothiolutin (2), together with the kn own compound, thiolutin (3) were identified from a marine-derived Streptomyces sp. BTBU20218885, which was isolated from a mud sample collected from the coastal region of Xiamen, China. Their chemical structures were determined using spectroscopic data, including HRESIMS, 1D and 2D NMR techniques. 1 possessed a unique unsymmetrical sulfur-containing thiolopyrrolone structure. All the compounds were tested for bioactivities against Staphylococcus aureus, Escherichia coli, Bacille Calmette–Guérin (BCG), Mycobacterium tuberculosis, and Candida albicans. 1 displayed antibacterial activities against BCG, M. tuberculosis, and S. aureus with minimum inhibitory concentration (MIC) values of 10, 10, and 100 μg/mL, respectively. Thiolutin (3) showed antibacterial activities against E. coli, BCG, M. tuberculosis, and S. aureus with MIC values of 6.25, 0.3125, 0.625, and 3.125 μg/mL, respectively. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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12 pages, 1706 KiB

Open AccessArticle

New Sorbicillinoids with Tea Pathogenic Fungus Inhibitory Effect from Marine-Derived Fungus Hypocrea jecorina H8

by Shun-Zhi Liu, Guang-Xin Xu, Feng-Ming He, Wei-Bo Zhang, Zhen Wu, Ming-Yu Li, Xi-Xiang Tang and Ying-Kun Qiu

Mar. Drugs 2022, 20(3), 213; https://doi.org/10.3390/md20030213 - 17 Mar 2022

Cited by 7 | Viewed by 2528

Abstract

Four new dimeric sorbicillinoids (1–3 and 5) and a new monomeric sorbicillinoid (4) as well as six known analogs (6–11) were purified from the fungal strain Hypocrea jecorina H8, which was obtained from [...] Read more.

Four new dimeric sorbicillinoids (1–3 and 5) and a new monomeric sorbicillinoid (4) as well as six known analogs (6–11) were purified from the fungal strain Hypocrea jecorina H8, which was obtained from mangrove sediment, and showed potent inhibitory activity against the tea pathogenic fungus Pestalotiopsis theae (P. theae). The planar structures of 1–5 were assigned by analyses of their UV, IR, HR-ESI-MS, and NMR spectroscopic data. All the compounds were evaluated for growth inhibition of tea pathogenic fungus P. theae. Compounds 5, 6, 8, 9, and 10 exhibited more potent inhibitory activities compared with the positive control hexaconazole with an ED₅₀ of 24.25 ± 1.57 µg/mL. The ED₅₀ values of compounds 5, 6, 8, 9, and 10 were 9.13 ± 1.25, 2.04 ± 1.24, 18.22 ± 1.29, 1.83 ± 1.37, and 4.68 ± 1.44 µg/mL, respectively. Additionally, the effects of these compounds on zebrafish embryo development were also evaluated. Except for compounds 5 and 8, which imparted toxic effects on zebrafish even at 0.625 μM, the other isolated compounds did not exhibit significant toxicity to zebrafish eggs, embryos, or larvae. Taken together, sorbicillinoid derivatives (6, 9, and 10) from H. jecorina H8 displayed low toxicity and high anti-tea pathogenic fungus potential. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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12 pages, 1385 KiB

Open AccessEditor’s ChoiceArticle

Bacillimidazoles A−F, Imidazolium-Containing Compounds Isolated from a Marine Bacillus

by Jia-Xuan Yan, Qihao Wu, Eric J. N. Helfrich, Marc G. Chevrette, Doug R. Braun, Heino Heyman, Gene E. Ananiev, Scott R. Rajski, Cameron R. Currie, Jon Clardy and Tim S. Bugni

Mar. Drugs 2022, 20(1), 43; https://doi.org/10.3390/md20010043 - 01 Jan 2022

Cited by 7 | Viewed by 4529

Abstract

Chemical investigations of a marine sponge-associated Bacillus revealed six new imidazolium-containing compounds, bacillimidazoles A–F (1–6). Previous reports of related imidazolium-containing natural products are rare. Initially unveiled by timsTOF (trapped ion mobility spectrometry) MS data, extensive HRMS and 1D and [...] Read more.

Chemical investigations of a marine sponge-associated Bacillus revealed six new imidazolium-containing compounds, bacillimidazoles A–F (1–6). Previous reports of related imidazolium-containing natural products are rare. Initially unveiled by timsTOF (trapped ion mobility spectrometry) MS data, extensive HRMS and 1D and 2D NMR analyses enabled the structural elucidation of 1–6. In addition, a plausible biosynthetic pathway to bacillimidazoles is proposed based on isotopic labeling experiments and invokes the highly reactive glycolytic adduct 2,3-butanedione. Combined, the results of structure elucidation efforts, isotopic labeling studies and bioinformatics suggest that 1–6 result from a fascinating intersection of primary and secondary metabolic pathways in Bacillus sp. WMMC1349. Antimicrobial assays revealed that, of 1–6, only compound six displayed discernible antibacterial activity, despite the close structural similarities shared by all six natural products. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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12 pages, 3270 KiB

Open AccessArticle

New Prenylated Indole Homodimeric and Pteridine Alkaloids from the Marine-Derived Fungus Aspergillus austroafricanus Y32-2

by Peihai Li, Mengqi Zhang, Haonan Li, Rongchun Wang, Hairong Hou, Xiaobin Li, Kechun Liu and Hao Chen

Mar. Drugs 2021, 19(2), 98; https://doi.org/10.3390/md19020098 - 09 Feb 2021

Cited by 16 | Viewed by 2775

Abstract

Chemical investigation of secondary metabolites from the marine-derived fungus Aspergillus austroafricanus Y32-2 resulted in the isolation of two new prenylated indole alkaloid homodimers, di-6-hydroxydeoxybrevianamide E (1) and dinotoamide J (2), one new pteridine alkaloid asperpteridinate A (3), [...] Read more.

Chemical investigation of secondary metabolites from the marine-derived fungus Aspergillus austroafricanus Y32-2 resulted in the isolation of two new prenylated indole alkaloid homodimers, di-6-hydroxydeoxybrevianamide E (1) and dinotoamide J (2), one new pteridine alkaloid asperpteridinate A (3), with eleven known compounds (4–14). Their structures were elucidated by various spectroscopic methods including HRESIMS and NMR, while their absolute configurations were determined by ECD calculations. Each compound was evaluated for pro-angiogenic, anti-inflammatory effects in zebrafish models and cytotoxicity for HepG2 human liver carcinoma cells. As a result, compounds 2, 4, 5, 7, 10 exhibited pro-angiogenic activity in a PTK787-induced vascular injury zebrafish model in a dose-dependent manner, compounds 7, 8, 10, 11 displayed anti-inflammatory activity in a CuSO₄-induced zebrafish inflammation model, and compound 6 showed significant cytotoxicity against HepG2 cells with an IC₅₀ value of 30 µg/mL. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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Review

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32 pages, 9725 KiB

Open AccessEditor’s ChoiceReview

The Tetrahydrofuran Motif in Marine Lipids and Terpenes

by Paula González-Andrés, Laura Fernández-Peña, Carlos Díez-Poza and Asunción Barbero

Mar. Drugs 2022, 20(10), 642; https://doi.org/10.3390/md20100642 - 15 Oct 2022

Cited by 9 | Viewed by 2686

Abstract

Heterocycles are particularly common moieties within marine natural products. Specifically, tetrahydrofuranyl rings are present in a variety of compounds which present complex structures and interesting biological activities. Focusing on terpenoids, a high number of tetrahydrofuran-containing metabolites have been isolated during the last decades. [...] Read more.

Heterocycles are particularly common moieties within marine natural products. Specifically, tetrahydrofuranyl rings are present in a variety of compounds which present complex structures and interesting biological activities. Focusing on terpenoids, a high number of tetrahydrofuran-containing metabolites have been isolated during the last decades. They show promising biological activities, making them potential leads for novel antibiotics, antikinetoplastid drugs, amoebicidal substances, or anticancer drugs. Thus, they have attracted the attention of the synthetics community and numerous approaches to their total syntheses have appeared. Here, we offer the reader an overview of marine-derived terpenoids and related compounds, their isolation, structure determination, and a special focus on their total syntheses and biological profiles. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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33 pages, 7773 KiB

Open AccessReview

The Tetrahydrofuran Motif in Polyketide Marine Drugs

by Laura Fernández-Peña, Carlos Díez-Poza, Paula González-Andrés and Asunción Barbero

Mar. Drugs 2022, 20(2), 120; https://doi.org/10.3390/md20020120 - 03 Feb 2022

Cited by 13 | Viewed by 3406

Abstract

Oxygen heterocycles are units that are abundant in a great number of marine natural products. Among them, marine polyketides containing tetrahydrofuran rings have attracted great attention within the scientific community due to their challenging structures and promising biological activities. An overview of the [...] Read more.

Oxygen heterocycles are units that are abundant in a great number of marine natural products. Among them, marine polyketides containing tetrahydrofuran rings have attracted great attention within the scientific community due to their challenging structures and promising biological activities. An overview of the most important marine tetrahydrofuran polyketides, with a focused discussion on their isolation, structure determination, approaches to their total synthesis, and biological studies is provided. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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28 pages, 7475 KiB

Open AccessReview

Advances in Phenazines over the Past Decade: Review of Their Pharmacological Activities, Mechanisms of Action, Biosynthetic Pathways and Synthetic Strategies

by Junjie Yan, Weiwei Liu, Jiatong Cai, Yiming Wang, Dahong Li, Huiming Hua and Hao Cao

Mar. Drugs 2021, 19(11), 610; https://doi.org/10.3390/md19110610 - 27 Oct 2021

Cited by 26 | Viewed by 3776

Abstract

Phenazines are a large group of nitrogen-containing heterocycles, providing diverse chemical structures and various biological activities. Natural phenazines are mainly isolated from marine and terrestrial microorganisms. So far, more than 100 different natural compounds and over 6000 synthetic derivatives have been found and [...] Read more.

Phenazines are a large group of nitrogen-containing heterocycles, providing diverse chemical structures and various biological activities. Natural phenazines are mainly isolated from marine and terrestrial microorganisms. So far, more than 100 different natural compounds and over 6000 synthetic derivatives have been found and investigated. Many phenazines show great pharmacological activity in various fields, such as antimicrobial, antiparasitic, neuroprotective, insecticidal, anti-inflammatory and anticancer activity. Researchers continued to investigate these compounds and hope to develop them as medicines. Cimmino et al. published a significant review about anticancer activity of phenazines, containing articles from 2000 to 2011. Here, we mainly summarize articles from 2012 to 2021. According to sources of compounds, phenazines were categorized into natural phenazines and synthetic phenazine derivatives in this review. Their pharmacological activities, mechanisms of action, biosynthetic pathways and synthetic strategies were summarized. These may provide guidance for the investigation on phenazines in the future. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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79 pages, 20819 KiB

Open AccessReview

Marine Pyrrole Alkaloids

by Kevin Seipp, Leander Geske and Till Opatz

Mar. Drugs 2021, 19(9), 514; https://doi.org/10.3390/md19090514 - 10 Sep 2021

Cited by 36 | Viewed by 5485

Abstract

Nitrogen heterocycles are essential parts of the chemical machinery of life and often reveal intriguing structures. They are not only widespread in terrestrial habitats but can also frequently be found as natural products in the marine environment. This review highlights the important class [...] Read more.

Nitrogen heterocycles are essential parts of the chemical machinery of life and often reveal intriguing structures. They are not only widespread in terrestrial habitats but can also frequently be found as natural products in the marine environment. This review highlights the important class of marine pyrrole alkaloids, well-known for their diverse biological activities. A broad overview of the marine pyrrole alkaloids with a focus on their isolation, biological activities, chemical synthesis, and derivatization covering the decade from 2010 to 2020 is provided. With relevant structural subclasses categorized, this review shall provide a clear and timely synopsis of this area. Full article

(This article belongs to the Special Issue Heterocyclic Compounds from Marine Organisms)

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