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Natural Products from Terrestrial and Marine Sources: Chemical Characterization and Biological Activity

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (1 June 2021) | Viewed by 21765

Special Issue Editor

Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725, USA
Interests: conotoxins; Veratrum alkaloids; chemistry and bioactivity of natural products from marine and terrestrial sources; food and dairy chemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The chemical characterization and biological activity evaluation of compounds from terrestrial and marine sources have led to the discovery of the majority of current therapeutic drugs administered to patients. The evolution of chemical instrumentation, customization of cell lines and bioactivity assays, and modern approaches to the investigation of natural products have created an exciting combination of conditions for the exploration and unearthing of the secrets that nature holds.

This Special Issue provides a venue for the publication of review or research articles describing the chemical characterization and biological activity evaluation of natural products derived from terrestrial and marine sources. Natural products are broadly defined as compounds produced by living organisms, including peptides/proteins, carbohydrates, lipids, alkaloids, flavonoids, phenolics, or myriad other constituents from plants, animals, food products (fruits, nuts, dairy, grains, etc.), or marine organisms (snails, sponges, algae, etc.) Reports of chemical characterization methods, results, and implications may stand alone, but are preferentially considered for publication when coupled with the assessment of activity in cell line assays, toxicity screens, or in vivo testing.

Prof. Dr. Owen M. McDougal
Guest Editor

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Keywords

  • Marine toxins
  • Plant alkaloids
  • Plant secondary metabolites
  • Plant bioactive components
  • Marine bioactive compounds
  • Isolation and characterization of natural products

Published Papers (8 papers)

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Research

Jump to: Review

8 pages, 1221 KiB  
Article
Asperflaloids A and B from Aspergillus flavipes DZ-3, an Endophytic Fungus of Eucommia ulmoides Oliver
by Wan Liu, Yu Liu, Fan Yang, Shouye Han, Jia Zhang, Hui Yang, Zhongbin Cheng and Qin Li
Molecules 2021, 26(12), 3514; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26123514 - 09 Jun 2021
Cited by 6 | Viewed by 2006
Abstract
The fungus strain DZ-3 was isolated from twigs of the well-known medicinal plant Eucommia ulmoides Oliver and identified as Aspergillus flavipes. Two new alkaloids, named asperflaloids A and B (1 and 2), together with 10 known compounds (3 [...] Read more.
The fungus strain DZ-3 was isolated from twigs of the well-known medicinal plant Eucommia ulmoides Oliver and identified as Aspergillus flavipes. Two new alkaloids, named asperflaloids A and B (1 and 2), together with 10 known compounds (312) were obtained from the EtOAc extract of the strain. Interestingly, the alkaloids 14 with different frameworks are characterized by the presence of the same anthranilic acid residue. The structures were established by detailed analyses of the spectroscopic data. The absolute configuration of asperflaloids A and B was resolved by quantum chemistry calculation. All compounds were screened for their inhibitions against α-glucosidase and the antioxidant capacities. The results were that compound 3 had an IC50 value of 750.8 μM toward α-glucosidase, and the phenol compounds 7 and 8 exhibited potent antioxidant capacities with IC50 values 14.4 and 27.1 μM respectively. Full article
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10 pages, 1430 KiB  
Article
Polyoxygenated Klysimplexane- and Eunicellin-Based Diterpenoids from the Gorgonian Briareum violaceum
by Atallah F. Ahmed, Yang Cheng, Chang-Feng Dai and Jyh-Horng Sheu
Molecules 2021, 26(11), 3276; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26113276 - 28 May 2021
Viewed by 1666
Abstract
Three new polyoxygenated diterpenoids with a rare 4-isopropyl-1,5,8a-trimethylperhydrophenanthrane structure of the klysimplexane skeleton, briarols A‒C (1‒3), and one eunicellin-based diterpenoid, briarol D (4), were isolated from Briareum violaceum, a gorgonian inhabiting Taiwanese waters. The chemical structures of these compounds were determined by [...] Read more.
Three new polyoxygenated diterpenoids with a rare 4-isopropyl-1,5,8a-trimethylperhydrophenanthrane structure of the klysimplexane skeleton, briarols A‒C (1‒3), and one eunicellin-based diterpenoid, briarol D (4), were isolated from Briareum violaceum, a gorgonian inhabiting Taiwanese waters. The chemical structures of these compounds were determined by employing extensive analyses of NMR and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Metabolites 1‒3 were found to possess the rarely found skeleton of the diterpenoid klysimplexin T. All isolated compounds showed very weak cytotoxic activity against the growth of three cancer cell lines. A plausible biosynthetic pathway for briarols A‒C from the coexisting eunicellin diterpenoid briarol D (4) was postulated. Full article
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12 pages, 1253 KiB  
Article
Immune Modulatory Activities of Arginyl-Fructose (AF) and AF-Enriched Natural Products in In-Vitro and In-Vivo Animal Models
by Jin-A Yu, Jung-Yun Lee, Tae Yang Kim, Hanna Kang, Su-Young Lee, Haimanot Mitiku, Joonheum Park, Young Hwan Lee, Hung-Bae Chang, Byung Ha Lee, Kichoon Lee, Emmanouil Apostolidis and Young-In Kwon
Molecules 2021, 26(8), 2251; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26082251 - 13 Apr 2021
Cited by 4 | Viewed by 1916
Abstract
The immune system plays an important role in maintaining body homeostasis. Recent studies on the immune-enhancing effects of ginseng saponins have revealed more diverse mechanisms of action. Maillard reaction that occurs during the manufacturing processes of red ginseng produces a large amount of [...] Read more.
The immune system plays an important role in maintaining body homeostasis. Recent studies on the immune-enhancing effects of ginseng saponins have revealed more diverse mechanisms of action. Maillard reaction that occurs during the manufacturing processes of red ginseng produces a large amount of Amadori rearrangement compounds (ARCs), such as arginyl-fructose (AF). The antioxidant and anti-hyperglycemic effects of AF have been reported. However, the possible immune enhancing effects of non-saponin ginseng compounds, such as AF, have not been investigated. In this study the effects of AF and AF-enriched natural product (Ginofos, GF) on proliferation of normal mouse splenocytes were evaluated in vitro and male BALB/c mice models. The proliferation of splenocytes treated with mitogens (concanavalin A, lipopolysaccharide) were further increased by addition of AF (p < 0.01) or GF (p < 0.01), in a dose dependent manner. After the 10 days of oral administration of compounds, changes in weights of spleen and thymus, serum immunoglobulin, and expression of cytokines were measured as biomarkers of immune-enhancing potential in male BALB/c mice model. The AF or GF treated groups had higher weights of the thymus (0.94 ± 0.25 and 0.86 ± 0.18, p < 0.05, respectively) than that of cyclophosphamide treated group (0.59 ± 0.18). This result indicates that AF or AF-enriched extract (GF) increased humoral immunity against CY-induced immunosuppression. In addition, immunoglobulin contents and expression of cytokines including IgM (p < 0.01), IgG (p < 0.05), IL-2 (p < 0.01), IL-4 (p < 0.01), IL-6 (p < 0.01), and IFN-γ (p < 0.05) were also significantly increased by supplementation of AF or GF. These results indicate that AF has immune enhancing effects by activation of adaptive immunity via increase of expression of immunoglobulins and cytokines such as IgM, IgG, IL-2, IL-4, IL-6 and thereby proliferating the weight of thymus. Our findings provide a pharmacological rationale for AF-enriched natural products such as ginseng and red ginseng that can possibly have immune-enhancement potential and should be further evaluated. Full article
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13 pages, 937 KiB  
Article
Triterpenes and Phenolic Compounds from the Fungus Fuscoporia torulosa: Isolation, Structure Determination and Biological Activity
by Zoltán Béni, Miklós Dékány, András Sárközy, Annamária Kincses, Gabriella Spengler, Viktor Papp, Judit Hohmann and Attila Ványolós
Molecules 2021, 26(6), 1657; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26061657 - 16 Mar 2021
Cited by 7 | Viewed by 2581
Abstract
Investigation of the methanol extract of the poroid fungus Fuscoporia torulosa resulted in the isolation of a novel triterpene, fuscoporic acid (1), together with inoscavin A and its previously undescribed Z isomer (2 and 3), 3,4-dihydroxy-benzaldehide (4), [...] Read more.
Investigation of the methanol extract of the poroid fungus Fuscoporia torulosa resulted in the isolation of a novel triterpene, fuscoporic acid (1), together with inoscavin A and its previously undescribed Z isomer (2 and 3), 3,4-dihydroxy-benzaldehide (4), osmundacetone (5), senexdiolic acid (6), natalic acid (7), and ergosta-7,22-diene-3-one (8). The structures of fungal compounds were determined on the basis of NMR and MS spectroscopic analyses, as well as molecular modeling studies. Compounds 1, 68 were examined for their antibacterial properties on resistant clinical isolates, and cytotoxic activity on human colon adenocarcinoma cell lines. Compound 8 was effective against Colo 205 (IC50 11.65 ± 1.67 µM), Colo 320 (IC50 8.43 ± 1.1 µM) and MRC-5 (IC50 7.92 ± 1.42 µM) cell lines. Potentially synergistic relationship was investigated between 8 and doxorubicin, which revealed a synergism between the examined compounds with a combination index (CI) at the 50% growth inhibition dose (ED50) of 0.521 ± 0.15. Several compounds (1 and 68) were tested for P-glycoprotein modulatory effect in Colo 320 resistant cancer cells, but none of the compounds proved to be effective in this assay. Fungal metabolites 25 were evaluated for their antioxidant activity using the oxygen radical absorbance capacity (ORAC) and DPPH assays. Compounds 4 and 5 were found to have a considerable antioxidant effect with EC50 0.25 ± 0.01 (DPPH) and 12.20 ± 0.92 mmol TE/g (ORAC). The current article provides valuable information on both the chemical and pharmacological profiles of Fuscoporia torulosa, paving the way for future studies with this species. Full article
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11 pages, 817 KiB  
Article
Juncaceae Species as Promising Sources of Phenanthrenes: Antiproliferative Compounds from Juncus maritimus Lam
by Norbert Kúsz, Dóra Stefkó, Anita Barta, Annamária Kincses, Nikoletta Szemerédi, Gabriella Spengler, Judit Hohmann and Andrea Vasas
Molecules 2021, 26(4), 999; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26040999 - 13 Feb 2021
Cited by 3 | Viewed by 2346
Abstract
Juncaceae family represents an abundant source of phenanthrenes. In continuation of our work aiming at the isolation of biologically active compounds from Juncaceae species, Juncus maritimus Lam. was subjected to phytochemical and pharmacological investigations. The isolation process was carried out by using combined [...] Read more.
Juncaceae family represents an abundant source of phenanthrenes. In continuation of our work aiming at the isolation of biologically active compounds from Juncaceae species, Juncus maritimus Lam. was subjected to phytochemical and pharmacological investigations. The isolation process was carried out by using combined extraction and chromatographic methods. The structures of the obtained chemical compounds were elucidated by spectroscopic analysis, including HRESIMS, 1D (1H, 13C-JMOD), and 2D (1H-1H-COSY, HSQC, HMBC, NOESY) NMR spectra. Four new [maritins A–D (14)] and seven known phenanthrenes (511) were isolated from the plant, of which two (4 and 11) are phenanthrene dimers composed of effusol monomers. Maritin C (3) has an unusual 4,5-ethanophenanthrene skeleton most likely produced by biosynthetic incorporation of a vinyl group into a cyclohexadiene ring. Compounds 111 were tested for their antiproliferative activity on seven human tumor cell lines (HeLa, HTM-26, T-47D, A2780, A2780cis, MCF-7, KCR) and one normal cell line (MRC-5) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The dimeric phenanthrenes showed strong antiproliferative activity against T-47D cells with IC50 values of 9.1 and 6.2 µM, respectively. Full article
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Review

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20 pages, 3463 KiB  
Review
Review: Veratrum californicum Alkaloids
by Madison L. Dirks, Jared T. Seale, Joseph M. Collins and Owen M. McDougal
Molecules 2021, 26(19), 5934; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26195934 - 30 Sep 2021
Cited by 14 | Viewed by 2649
Abstract
Veratrum spp. grow throughout the world and are especially prevalent in high mountain meadows of North America. All parts of Veratrum plants have been used for the treatment of ailments including injuries, hypertension, and rheumatic pain since as far back as the 1600s. [...] Read more.
Veratrum spp. grow throughout the world and are especially prevalent in high mountain meadows of North America. All parts of Veratrum plants have been used for the treatment of ailments including injuries, hypertension, and rheumatic pain since as far back as the 1600s. Of the 17–45 Veratrum spp., Veratrum californicum alkaloids have been proven to possess favorable medicinal properties associated with inhibition of hedgehog (Hh) pathway signaling. Aberrant Hh signaling leads to proliferation of over 20 cancers, including basal cell carcinoma, prostate and colon among others. Six of the most well-studied V. californicum alkaloids are cyclopamine (1), veratramine (2), isorubijervine (3), muldamine (4), cycloposine (5), and veratrosine (6). Recent inspection of the ethanolic extract from V. californicum root and rhizome via liquid chromatography–mass spectrometry has detected up to five additional alkaloids that are proposed to be verazine (7), etioline (8), tetrahydrojervine (9), dihydrojervine (10), 22-keto-26-aminocholesterol (11). For each alkaloid identified or proposed in V. californicum, this review surveys literature precedents for extraction methods, isolation, identification, characterization and bioactivity to guide natural product drug discovery associated with this medicinal plant. Full article
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39 pages, 12606 KiB  
Review
Biological Activity of Naturally Derived Naphthyridines
by Gabriela Chabowska, Ewa Barg and Anna Wójcicka
Molecules 2021, 26(14), 4324; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules26144324 - 16 Jul 2021
Cited by 9 | Viewed by 2609
Abstract
Marine and terrestrial environments are rich sources of various bioactive substances, which have been used by humans since prehistoric times. Nowadays, due to advances in chemical sciences, new substances are still discovered, and their chemical structures and biological properties are constantly explored. Drugs [...] Read more.
Marine and terrestrial environments are rich sources of various bioactive substances, which have been used by humans since prehistoric times. Nowadays, due to advances in chemical sciences, new substances are still discovered, and their chemical structures and biological properties are constantly explored. Drugs obtained from natural sources are used commonly in medicine, particularly in cancer and infectious diseases treatment. Naphthyridines, isolated mainly from marine organisms and terrestrial plants, represent prominent examples of naturally derived agents. They are a class of heterocyclic compounds containing a fused system of two pyridine rings, possessing six isomers depending on the nitrogen atom’s location. In this review, biological activity of naphthyridines obtained from various natural sources was summarized. According to previous studies, the naphthyridine alkaloids displayed multiple activities, i.a., antiinfectious, anticancer, neurological, psychotropic, affecting cardiovascular system, and immune response. Their wide range of activity makes them a fascinating object of research with prospects for use in therapeutic purposes. Full article
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18 pages, 827 KiB  
Review
Anticancer Drug Discovery from Microbial Sources: The Unique Mangrove Streptomycetes
by Jodi Woan-Fei Law, Lydia Ngiik-Shiew Law, Vengadesh Letchumanan, Loh Teng-Hern Tan, Sunny Hei Wong, Kok-Gan Chan, Nurul-Syakima Ab Mutalib and Learn-Han Lee
Molecules 2020, 25(22), 5365; https://0-doi-org.brum.beds.ac.uk/10.3390/molecules25225365 - 17 Nov 2020
Cited by 55 | Viewed by 5192
Abstract
Worldwide cancer incidence and mortality have always been a concern to the community. The cancer mortality rate has generally declined over the years; however, there is still an increased mortality rate in poorer countries that receives considerable attention from healthcare professionals. This suggested [...] Read more.
Worldwide cancer incidence and mortality have always been a concern to the community. The cancer mortality rate has generally declined over the years; however, there is still an increased mortality rate in poorer countries that receives considerable attention from healthcare professionals. This suggested the importance of the prompt detection, effective treatment, and prevention strategies. The genus Streptomyces has been documented as a prolific producer of biologically active secondary metabolites. Streptomycetes from mangrove environments attract researchers’ attention due to their ability to synthesize diverse, interesting bioactive metabolites. The present review highlights research on mangrove-derived streptomycetes and the production of anticancer-related compounds from these microorganisms. Research studies conducted between 2008 and 2019, specifically mentioning the isolation of streptomycetes from mangrove areas and described the successful purification of compound(s) or generation of crude extracts with cytotoxic activity against human cancer cell lines, were compiled in this review. It is anticipated that there will be an increase in prospects for mangrove-derived streptomycetes as one of the natural resources for the isolation of chemotherapeutic agents. Full article
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