A Theme Issue Honoring Professor Peter Proksch's 70th Birthday: Bioactive Compounds from the Ocean

A special issue of Marine Drugs (ISSN 1660-3397). This special issue belongs to the section "Structural Studies on Marine Natural Products".

Deadline for manuscript submissions: closed (6 December 2023) | Viewed by 28469

Special Issue Editors


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Guest Editor
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Nanhai Road 7, Qingdao 266071, China
Interests: natural product chemistry; bioactive compounds; drug discovery; structure determination
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Hainan Institute for Tropical Agricultural Resources, CATAS, Haikou 571101, China
Interests: natural product chemistry; bioactive compounds; drug discovery; structure determination

Special Issue Information

Dear Colleagues,

This commemorative Special Issue on bioactive compounds from the ocean is in honor of Prof. Dr. Peter Proksch for his 70th birthday. Prof. Dr. Proksch is an internationally recognized scientist in research on both terrestrial and marine natural products.

Marine organisms live in a complex chemical buffer system of seawater with higher pressure and salinity, lower temperature, and limited dissolved oxygen and sunlight. To cope with the special environmental stresses, marine organisms have evolved specific genetic capabilities to produce novel bioactive products or so-called small-molecule secondary metabolites, which play important roles in adaptation to environments, species communication, and biotechnological as well as pharmaceutical applications.

Prof. Dr. Proksch worked with terrestrial plants in the early stage of his career and started to work on marine natural products some thirty years ago. He once said, “When I started to work on marine natural products I was attracted to this fascinating field of science by the exotic environment, the colourful shapes of (mostly) marine invertebrates and their complex ecological interactions”. In parallel to marine macroorganisms, he soon embarked on studying natural products from marine-derived microorganisms, discovering a huge amount of biodiversity and highly unusual and complex microbial natural products.

In honor and recognition of Prof. Dr. Proksch’s outstanding contributions to research on marine natural products, this Special Issue welcomes the submission of original research articles, reviews, and communications in this research field. The topics of this Special Issue include, but are not limited to:

  • Isolation, structure elucidation, and bioactivity of new molecules from marine organisms.
  • Characterization of proteins, enzymes, and saccharides from marine organisms.
  • Biosynthesis of bioactive compounds from marine organisms.
  • Design, synthesis, modification, and structure–activity relationship of bioactive compounds from marine organisms.
  • Pharmacological mechanisms of bioactive compounds from marine organisms.

Prof. Dr. Bin-Gui Wang
Prof. Dr. Haofu Dai
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Marine Drugs is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • marine natural products
  • bioactive compounds
  • chemical structure
  • biosynthetic pathway
  • pharmacological mechanism

Published Papers (15 papers)

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Research

19 pages, 5939 KiB  
Article
Metabolomics-Guided Discovery of New Dimeric Xanthones from Co-Cultures of Mangrove Endophytic Fungi Phomopsis asparagi DHS-48 and Phomopsis sp. DHS-11
by Jingwan Wu, Dandan Chen, Qing Li, Ting Feng and Jing Xu
Mar. Drugs 2024, 22(3), 102; https://doi.org/10.3390/md22030102 - 23 Feb 2024
Cited by 2 | Viewed by 1690
Abstract
The co-culture strategy, which mimics natural ecology by constructing an artificial microbial community, is a useful tool for the activation of biosynthetic gene clusters (BGCs) to generate new metabolites, as well as to increase the yield of respective target metabolites. As part of [...] Read more.
The co-culture strategy, which mimics natural ecology by constructing an artificial microbial community, is a useful tool for the activation of biosynthetic gene clusters (BGCs) to generate new metabolites, as well as to increase the yield of respective target metabolites. As part of our project aiming at the discovery of structurally novel and biologically active natural products from mangrove endophytic fungi, we selected the co-culture of a strain of Phomopsis asparagi DHS-48 with another Phomopsis genus fungus DHS-11, both endophyted in mangrove Rhizophora mangle considering the impart of the taxonomic criteria and ecological data. The competition interaction of the two strains was investigated through morphology observation and scanning electron microscopy (SEM), and it was found that the mycelia of the DHS-48 and DHS-11 compacted and tangled with each other with an interwoven pattern in the co-culture system. A new approach that integrates HPLC chromatogram, 1HNMR spectroscopy, UPLC-MS-PCA, and molecular networking enabled the targeted isolation of the induced metabolites, including three new dimeric xanthones phomoxanthones L-N (13), along with six known analogs (49). Their planar structures were elucidated by an analysis of their HRMS, MS/MS, and NMR spectroscopic data and the absolute configurations based on ECD calculations. These metabolites showed broad cytotoxic activity against the cancer cells assessed, of which compounds 79 displayed significant cytotoxicity towards human liver cells HepG-2 with IC50 values ranging from 4.83 μM to 12.06 μM. Compounds 16 exhibited weak immunosuppressive activity against the proliferation of ConA-induced (T-cell) and LPS-induced (B-cell) murine splenic lymphocytes. Therefore, combining co-cultivation with a metabolomics-guided strategy as a discovery tool will be implemented as a systematic strategy for the quick discovery of target bioactive compounds. Full article
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14 pages, 2208 KiB  
Article
Indole Diketopiperazine Alkaloids from the Marine Sediment-Derived Fungus Aspergillus chevalieri against Pancreatic Ductal Adenocarcinoma
by Dina H. El-Kashef, Deborah D. Obidake, Katja Schiedlauske, Alina Deipenbrock, Sebastian Scharf, Hao Wang, Daniela Naumann, Daniel Friedrich, Simone Miljanovic, Takin Haj Hassani Sohi, Christoph Janiak, Klaus Pfeffer and Nicole Teusch
Mar. Drugs 2024, 22(1), 5; https://doi.org/10.3390/md22010005 - 20 Dec 2023
Viewed by 1886
Abstract
A new prenylated indole diketopiperazine alkaloid, rubrumline P (1), was isolated along with six more analogues and characterized from the fermentation culture of a marine sediment-derived fungus, Aspergillus chevalieri, collected at a depth of 15 m near the lighthouse in [...] Read more.
A new prenylated indole diketopiperazine alkaloid, rubrumline P (1), was isolated along with six more analogues and characterized from the fermentation culture of a marine sediment-derived fungus, Aspergillus chevalieri, collected at a depth of 15 m near the lighthouse in Dahab, Red Sea, Egypt. In the current study, a bioassay-guided fractionation allowed for the identification of an active fraction displaying significant cytotoxic activity against the human pancreatic adenocarcinoma cell line PANC-1 from the EtOAc extract of the investigated fungus compared to the standard paclitaxel. The structures of the isolated compounds from the active fraction were established using 1D/2D NMR spectroscopy and mass spectrometry, together with comparisons with the literature. The absolute configuration of the obtained indole diketopiperazines was established based on single-crystal X-ray diffraction analyses of rubrumline I (2) and comparisons of optical rotations and NMR data, as well as on biogenetic considerations. Genome sequencing indicated the formation of prenyltransferases, which was subsequently confirmed by the isolation of mono-, di-, tri-, and tetraprenylated compounds. Compounds rubrumline P (1) and neoechinulin D (4) confirmed preferential cytotoxic activity against PANC-1 cancer cells with IC50 values of 25.8 and 23.4 µM, respectively. Although the underlying mechanism-of-action remains elusive in this study, cell cycle analysis indicated a slight increase in the sub-G1 peak after treatment with compounds 1 and 4. Full article
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12 pages, 2634 KiB  
Article
Cytosporones with Anti-Inflammatory Activities from the Mangrove Endophytic Fungus Phomopsis sp. QYM-13
by Guisheng Wang, Yilin Yuan, Zhaokun Li, Junhao Zhu, Zhigang She and Yan Chen
Mar. Drugs 2023, 21(12), 631; https://doi.org/10.3390/md21120631 - 7 Dec 2023
Cited by 2 | Viewed by 1440
Abstract
Six previously undescribed cytosporone derivatives (phomotones A-E (15) and phomotone F (13)), two new spiro-alkanol phombistenes A-B (1415), and seven known analogs (612) were isolated from the mangrove endophytic [...] Read more.
Six previously undescribed cytosporone derivatives (phomotones A-E (15) and phomotone F (13)), two new spiro-alkanol phombistenes A-B (1415), and seven known analogs (612) were isolated from the mangrove endophytic fungus Phomopsis sp. QYM-13. The structures of these compounds were elucidated using spectroscopic data analysis, electronic circular dichroism (ECD), and 13C NMR calculations. Compound 14 features an unprecedented 1,6-dioxaspiro[4.5]decane ring system. All isolates were evaluated for their inhibitory effect on nitric oxide (NO) in LPS-induced RAW264.7 cells. The results showed that compounds 1, 6, 8, and 11 exhibited potent bioactivities by comparing with positive control. Then, compound 1 displayed the anti-inflammatory effect by inhibiting the MAPK/NF-κB signaling pathways. Molecular docking further revealed the possible mechanism of compound 1 interaction with ERK protein. Full article
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15 pages, 4484 KiB  
Article
Rhizoaspergillin A and Rhizoaspergillinol A, including a Unique Orsellinic Acid–Ribose–Pyridazinone-N-Oxide Hybrid, from the Mangrove Endophytic Fungus Aspergillus sp. A1E3
by Binbin Wu, Chenglong Xu, Jianjun Chen and Guangying Chen
Mar. Drugs 2023, 21(11), 598; https://doi.org/10.3390/md21110598 - 19 Nov 2023
Viewed by 1700
Abstract
Two new compounds, named rhizoaspergillin A (1) and rhizoaspergillinol A (2), were isolated from the mangrove endophytic fungus Aspergillus sp. A1E3, associated with the fruit of Rhizophora mucronata, together with averufanin (3). The planar structures and [...] Read more.
Two new compounds, named rhizoaspergillin A (1) and rhizoaspergillinol A (2), were isolated from the mangrove endophytic fungus Aspergillus sp. A1E3, associated with the fruit of Rhizophora mucronata, together with averufanin (3). The planar structures and absolute configurations of rhizoaspergillinol A (2) and averufanin (3) were established by extensive NMR investigations and quantum-chemical electronic circular dichroism (ECD) calculations. Most notably, the constitution and absolute configuration of rhizoaspergillin A (1) were unambiguously determined by single-crystal X-ray diffraction analysis of its tri-pivaloyl derivative 4, conducted with Cu Kα radiation, whereas those of averufanin (3) were first clarified by quantum-chemical ECD calculations. Rhizoaspergillin A is the first orsellinic acid–ribose–pyridazinone-N-oxide hybrid containing a unique β-oxo-2,3-dihydropyridazine 1-oxide moiety, whereas rhizoaspergillinol A (2) and averufanin (3) are sterigmatocystin and anthraquinone derivatives, respectively. From the perspective of biosynthesis, rhizoaspergillin A (1) could be originated from the combined assembly of three building blocks, viz., orsellinic acid, β-D-ribofuranose, and L-glutamine. It is an unprecedented alkaloid-N-oxide involving biosynthetic pathways of polyketides, pentose, and amino acids. In addition, rhizoaspergillinol A (2) exhibited potent antiproliferative activity against four cancer cell lines. It could dose-dependently induce G2/M phase arrest in HepG2 cells. Full article
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13 pages, 5049 KiB  
Article
Penidihydrocitrinins A–C: New Polyketides from the Deep-Sea-Derived Penicillium citrinum W17 and Their Anti-Inflammatory and Anti-Osteoporotic Bioactivities
by Yong Zhang, Chun-Lan Xie, Yuan Wang, Xi-Wen He, Ming-Min Xie, You Li, Kai Zhang, Zheng-Biao Zou, Long-He Yang, Ren Xu and Xian-Wen Yang
Mar. Drugs 2023, 21(10), 538; https://doi.org/10.3390/md21100538 - 14 Oct 2023
Cited by 4 | Viewed by 1696
Abstract
Three new polyketides (penidihydrocitrinins A–C, 13) and fourteen known compounds (417) were isolated from the deep-sea-derived Penicillium citrinum W17. Their structures were elucidated by comprehensive analyses of 1D and 2D NMR, HRESIMS, and ECD calculations. Compounds [...] Read more.
Three new polyketides (penidihydrocitrinins A–C, 13) and fourteen known compounds (417) were isolated from the deep-sea-derived Penicillium citrinum W17. Their structures were elucidated by comprehensive analyses of 1D and 2D NMR, HRESIMS, and ECD calculations. Compounds 117 were evaluated for their anti-inflammatory and anti-osteoporotic bioactivities. All isolates exhibited significant inhibitory effects on LPS-stimulated nitric oxide production in murine brain microglial BV-2 cells in a dose-response manner. Notably, compound 14 displayed the strongest effect with the IC50 value of 4.7 µM. Additionally, compounds 6, 7, and 8 significantly enhanced osteoblast mineralization, which was comparable to that of the positive control, purmorphamine. Furthermore, these three compounds also suppressed osteoclastogenesis in a dose-dependent manner under the concentrations of 2.5 μM, 5.0 μM, and 10 μM. Full article
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12 pages, 2051 KiB  
Article
New Fusarin Derivatives from the Marine Algicolous Fungus Penicillium steckii SCSIO41040
by Yingying Song, Jianglian She, Weihao Chen, Jiamin Wang, Yanhui Tan, Xiaoyan Pang, Xuefeng Zhou, Junfeng Wang and Yonghong Liu
Mar. Drugs 2023, 21(10), 532; https://doi.org/10.3390/md21100532 - 12 Oct 2023
Cited by 1 | Viewed by 1614
Abstract
Five new fusarin derivatives, steckfusarins A–E (15), and two known natural products (6, 7), were isolated and identified from the marine algicolous fungus Penicillium steckii SCSIO 41040. The new compounds, including absolute configurations, were determined by [...] Read more.
Five new fusarin derivatives, steckfusarins A–E (15), and two known natural products (6, 7), were isolated and identified from the marine algicolous fungus Penicillium steckii SCSIO 41040. The new compounds, including absolute configurations, were determined by spectroscopic analyses and calculated electronic circular dichroism (ECD). All new compounds were evaluated for their antioxidant, antibacterial, antifungal, antiviral, cytotoxic, anti-inflammatory, antioxidant, cholesterol-lowering, acetyl cholinesterase (AChE) enzyme and 6-phosphofructo-2-kinase (PFKFB3) and phosphatidylinositol-3-kinase (PI3K) inhibitory activities. The biological evaluation results revealed that compound 1 exhibited radical scavenging activity against 2,2-diphenyl-1-picrylhydrazylhydrate (DPPH), with an IC50 value of 74.5 µg/mL. In addition, compound 1 also showed weak anti-inflammatory activity at a concentration of 20 µM. Full article
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10 pages, 927 KiB  
Article
Trichoderols B-G, Six New Lipids from the Marine Algicolous Fungus Trichoderma sp. Z43
by Zhen-Zhen Shi, Xiu-Li Yin and Nai-Yun Ji
Mar. Drugs 2023, 21(8), 453; https://doi.org/10.3390/md21080453 - 17 Aug 2023
Cited by 1 | Viewed by 1230
Abstract
Six new lipids, trichoderols B-G (16), along with a known one, triharzianin B (7), were isolated from the culture of Trichoderma sp. Z43 obtained from the surface of the marine brown alga Dictyopteris divaricata. Their structures [...] Read more.
Six new lipids, trichoderols B-G (16), along with a known one, triharzianin B (7), were isolated from the culture of Trichoderma sp. Z43 obtained from the surface of the marine brown alga Dictyopteris divaricata. Their structures and relative configurations were identified by interpretation of 1D/2D NMR and MS data. Compounds 17 were assayed for inhibiting the growth of three phytopathogenic fungi (Fusarium graminearum, Gaeumannomyces graminis, and Glomerella cingulata), four marine phytoplankton species (Amphidinium carterae, Heterocapsa circularisquama, Heterosigma akashiwo, and Prorocentrum donghaiense), and one marine zooplankton (Artemia salina). Compounds 1, 4, and 7 exhibited weak antifungal activities against three phytopathogenic fungi tested with MIC ≥ 64 μg/mL. All compounds displayed moderate antimicroalgal activity with IC50 ≥ 15 μg/mL and low toxicity to the brine shrimp Artemia salina. Full article
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21 pages, 1939 KiB  
Article
Pentaketides and 5-p-Hydroxyphenyl-2-pyridone Derivative from the Culture Extract of a Marine Sponge-Associated Fungus Hamigera avellanea KUFA0732
by Rotchana Klaram, Tida Dethoup, Fátima P. Machado, Luís Gales, Decha Kumla, Salar Hafez Ghoran, Emília Sousa, Sharad Mistry, Artur M. S. Silva and Anake Kijjoa
Mar. Drugs 2023, 21(6), 344; https://doi.org/10.3390/md21060344 - 2 Jun 2023
Cited by 2 | Viewed by 1717
Abstract
Five undescribed pentaketide derivatives, (R)-6,8-dihydroxy-4,5-dimethyl-3-methylidene-3,4-dihydro-1H-2-benzopyran-1-one (1), [(3S,4R)-3,8-dihydroxy-6-methoxy-4,5-dimethyl-1-oxo-3,4-dihydro-1H-isochromen-3-yl]methyl acetate (2), (R)-5, 7-dimethoxy-3-((S)-(1-hydroxyethyl)-3,4-dimethylisobenzofuran-1(3H)-one (4b), (S)-7-hydroxy-3-((S)-1-hydroxyethyl)-5-methoxy-3,4-dimethylisobenzofuran 1(3H)-one ( [...] Read more.
Five undescribed pentaketide derivatives, (R)-6,8-dihydroxy-4,5-dimethyl-3-methylidene-3,4-dihydro-1H-2-benzopyran-1-one (1), [(3S,4R)-3,8-dihydroxy-6-methoxy-4,5-dimethyl-1-oxo-3,4-dihydro-1H-isochromen-3-yl]methyl acetate (2), (R)-5, 7-dimethoxy-3-((S)-(1-hydroxyethyl)-3,4-dimethylisobenzofuran-1(3H)-one (4b), (S)-7-hydroxy-3-((S)-1-hydroxyethyl)-5-methoxy-3,4-dimethylisobenzofuran 1(3H)-one (5), and a p-hydroxyphenyl-2-pyridone derivative, avellaneanone (6), were isolated together with the previously reported (R)-3-acetyl-7-hydroxy-5-methoxy-3,4-dimethylisobenzofuran-1(3H)-one (3), (R)-7-hydroxy-3-((S)-1-hydroxyethyl)-5-methoxy-3,4-dimethylisobenzofuran-1(3H)-one (4a) and isosclerone (7), from the ethyl acetate extract of a culture of a marine sponge-derived fungus, Hamigera avellanea KUFA0732. The structures of the undescribed compounds were elucidated using 1D and 2D NMR, as well as high-resolution mass spectral analyses. The absolute configurations of the stereogenic carbons in 1, 4b, 5, and 6 were established by X-ray crystallographic analysis. The absolute configurations of C-3 and C-4 in 2 were determined by ROESY correlations and on the basis of their common biosynthetic origin with 1. The crude fungal extract and the isolated compounds 1, 3, 4b, 5, 6, and 7 were assayed for their growth inhibitory activity against various plant pathogenic fungi viz. Alternaria brassicicola, Bipolaris oryzae, Colletotrichum capsici, C. gloeosporiodes, Curvularia oryzae, Fusarium semitectum, Lasiodiplodia theobromae, Phytophthora palmivora, Pyricularia oryzae, Rhizoctonia oryzae and Sclerotium rolfsii. Full article
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13 pages, 4443 KiB  
Article
Bioactive Polyketides and Benzene Derivatives from Two Mangrove Sediment-Derived Fungi in the Beibu Gulf
by Bo Peng, Jian Cai, Zimin Xiao, Manli Liu, Xinlong Li, Bin Yang, Wei Fang, Yi-You Huang, Chunmei Chen, Xuefeng Zhou and Huaming Tao
Mar. Drugs 2023, 21(6), 327; https://doi.org/10.3390/md21060327 - 26 May 2023
Cited by 6 | Viewed by 1821
Abstract
To discover bioactive natural products from mangrove sediment-derived microbes, a chemical investigation of the two Beibu Gulf-derived fungi strains, Talaromyces sp. SCSIO 41050 and Penicillium sp. SCSIO 41411, led to the isolation of 23 natural products. Five of them were identified as new [...] Read more.
To discover bioactive natural products from mangrove sediment-derived microbes, a chemical investigation of the two Beibu Gulf-derived fungi strains, Talaromyces sp. SCSIO 41050 and Penicillium sp. SCSIO 41411, led to the isolation of 23 natural products. Five of them were identified as new ones, including two polyketide derivatives with unusual acid anhydride moieties named cordyanhydride A ethyl ester (1) and maleicanhydridane (4), and three hydroxyphenylacetic acid derivatives named stachylines H–J (1012). Their structures were determined by detailed nuclear magnetic resonance (NMR) and mass spectroscopic (MS) analyses, while the absolute configurations were established by theoretical electronic circular dichroism (ECD) calculation. A variety of bioactive screens revealed three polyketide derivatives (13) with obvious antifungal activities, and 4 displayed moderate cytotoxicity against cell lines A549 and WPMY-1. Compounds 1 and 6 at 10 μM exhibited obvious inhibition against phosphodiesterase 4 (PDE4) with inhibitory ratios of 49.7% and 39.6%, respectively, while 5, 10, and 11 showed the potential of inhibiting acetylcholinesterase (AChE) by an enzyme activity test, as well as in silico docking analysis. Full article
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12 pages, 2588 KiB  
Article
Sclerotioloids A–C: Three New Alkaloids from the Marine-Derived Fungus Aspergillus sclerotiorum ST0501
by Jun-Qiu Mao, Yao-Yao Zheng, Chang-Yun Wang, Yang Liu and Guang-Shan Yao
Mar. Drugs 2023, 21(4), 219; https://doi.org/10.3390/md21040219 - 29 Mar 2023
Cited by 3 | Viewed by 1845
Abstract
Alkaloids, as one of the largest classes of natural products with diverse structures, are an important source of innovative medicines. Filamentous fungi, especially those derived from the marine environment, are one of the major producers of alkaloids. In this study, three new alkaloids, [...] Read more.
Alkaloids, as one of the largest classes of natural products with diverse structures, are an important source of innovative medicines. Filamentous fungi, especially those derived from the marine environment, are one of the major producers of alkaloids. In this study, three new alkaloids, sclerotioloids A–C (13), along with six known analogs (49), were obtained under the guidance of the MS/MS-based molecular networking from the marine-derived fungus, Aspergillus sclerotiorum ST0501, collected from the South China Sea. Their chemical structures were elucidated by comprehensive analysis of the spectroscopic data, including 1D and 2D NMR and HRESIMS. Additionally, the configuration of compound 2 was unambiguously determined by X-ray single crystal diffraction, and that of compound 3 was determined by the TDDFT-ECD approach. Sclerotioloid A (1) represents the first example of 2,5-diketopiperazine alkaloid with a rare terminal alkyne. Sclerotioloid B (2) showed the inhibition of NO production induced by lipopolysaccharide (LPS), with an inhibition rate of 28.92% higher than that of dexamethasone (25.87%). These results expanded the library of fungal-derived alkaloids and further prove the potential of marine fungi in the generation of alkaloids with new scaffolds. Full article
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11 pages, 3376 KiB  
Article
Antibacterial Indole Diketopiperazine Alkaloids from the Deep-Sea Cold Seep-Derived Fungus Aspergillus chevalieri
by Li-Hong Yan, Feng-Yu Du, Xiao-Ming Li, Sui-Qun Yang, Bin-Gui Wang and Xin Li
Mar. Drugs 2023, 21(3), 195; https://doi.org/10.3390/md21030195 - 22 Mar 2023
Cited by 7 | Viewed by 2168
Abstract
A large body of fungal secondary metabolites has been discovered to exhibit potent antibacterial activities with distinctive mechanisms and has the potential to be an untapped resource for drug discovery. Here, we describe the isolation and characterization of five new antibacterial indole diketopiperazine [...] Read more.
A large body of fungal secondary metabolites has been discovered to exhibit potent antibacterial activities with distinctive mechanisms and has the potential to be an untapped resource for drug discovery. Here, we describe the isolation and characterization of five new antibacterial indole diketopiperazine alkaloids, namely 24,25-dihydroxyvariecolorin G (1), 25-hydroxyrubrumazine B (2), 22-chloro-25-hydroxyrubrumazine B (3), 25-hydroxyvariecolorin F (4), and 27-epi-aspechinulin D (5), along with the known analogue neoechinulin B (6) from a fungal strain of deep-sea cold seep-derived Aspergillus chevalieri. Among these compounds, 3 and 4 represented a class of infrequently occurring fungal chlorinated natural products. Compounds 16 showed inhibitory activities against several pathogenic bacteria with MIC values ranging from 4 to 32 μg/mL. It was revealed that compound 6 could induce structural damage to the Aeromonas hydrophila cells based on the observation by scanning electron microscopy (SEM), which led to the bacteriolysis and death of A. hydrophila, suggesting that neoechinulin B (6) might be a potential alternative to novel antibiotics development. Full article
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11 pages, 1099 KiB  
Communication
Potential α-Glucosidase Inhibitors from the Deep-Sea Sediment-Derived Fungus Aspergillus insulicola
by Weibo Zhao, Yanbo Zeng, Wenjun Chang, Huiqin Chen, Hao Wang, Haofu Dai and Fang Lv
Mar. Drugs 2023, 21(3), 157; https://doi.org/10.3390/md21030157 - 26 Feb 2023
Cited by 4 | Viewed by 1835
Abstract
Three new phenolic compounds, epicocconigrones C–D (12) and flavimycin C (3), together with six known phenolic compounds: epicocconigrone A (4); 2-(10-formyl-11,13-dihydroxy-12-methoxy-14-methyl)-6,7-dihydroxy-5-methyl-4-benzofurancarboxaldehyde (5); epicoccolide B (6); eleganketal A (7); 1,3-dihydro-5-methoxy-7-methylisobenzofuran [...] Read more.
Three new phenolic compounds, epicocconigrones C–D (12) and flavimycin C (3), together with six known phenolic compounds: epicocconigrone A (4); 2-(10-formyl-11,13-dihydroxy-12-methoxy-14-methyl)-6,7-dihydroxy-5-methyl-4-benzofurancarboxaldehyde (5); epicoccolide B (6); eleganketal A (7); 1,3-dihydro-5-methoxy-7-methylisobenzofuran (8); and 2,3,4-trihydroxy-6-(hydroxymethyl)-5-methylbenzyl-alcohol (9), were isolated from fermentation cultures of a deep-sea sediment-derived fungus, Aspergillus insulicola. Their planar structures were elucidated based on the 1D and 2D NMR spectra and HRESIMS data. The absolute configurations of compounds 13 were determined by ECD calculations. Compound 3 represented a rare fully symmetrical isobenzofuran dimer. All compounds were evaluated for their α-glucosidase inhibitory activity, and compounds 1, 47, and 9 exhibited more potent α-glucosidase inhibitory effect with IC50 values ranging from 17.04 to 292.47 μM than positive control acarbose with IC50 value of 822.97 μM, indicating that these phenolic compounds could be promising lead compounds of new hypoglycemic drugs. Full article
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16 pages, 2430 KiB  
Article
New Azaphilones from the Marine-Derived Fungus Penicillium sclerotiorum E23Y-1A with Their Anti-Inflammatory and Antitumor Activities
by Yanbo Zeng, Zhi Wang, Wenjun Chang, Weibo Zhao, Hao Wang, Huiqin Chen, Haofu Dai and Fang Lv
Mar. Drugs 2023, 21(2), 75; https://doi.org/10.3390/md21020075 - 22 Jan 2023
Cited by 8 | Viewed by 2231
Abstract
Nine new azaphilones, including penicilazaphilones I–N (1, 2 and 69), epi-geumsanol D (3) and penidioxolanes C (4) and D (5) were isolated from the culture of the marine-derived fungus Penicillium sclerotiorum [...] Read more.
Nine new azaphilones, including penicilazaphilones I–N (1, 2 and 69), epi-geumsanol D (3) and penidioxolanes C (4) and D (5) were isolated from the culture of the marine-derived fungus Penicillium sclerotiorum E23Y-1A. The structures of the isolates were deduced from extensive spectroscopic data (1D and 2D NMR), high-resolution electrospray ionization mass spectrometry (HRESIMS), and electronic circular dichroism (ECD) calculations. All the azaphilones from P. sclerotiorum E23Y-1A were tested for their anti-inflammatory and antitumor activities. Penicilazaphilone N (9) showed moderate anti-inflammatory activity with an IC50 value of 22.63 ± 2.95 μM, whereas penidioxolane C (4) exhibited moderate inhibition against human myeloid leukemia cells (K562), human liver cancer cells (BEL-7402), human gastric cancer cells (SGC-7901), human non-small cell lung cancer cells (A549), and human hela cervical cancer cells, with IC50 values of 23.94 ± 0.11, 60.66 ± 0.13, 46.17 ± 0.17, 60.16 ± 0.26, and 59.30 ± 0.60 μM, respectively. Full article
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14 pages, 3308 KiB  
Article
Structurally Diverse Diterpenes from the South China Sea Soft Coral Sarcophyton trocheliophorum
by Yu-Ting Song, Dan-Dan Yu, Ming-Zhi Su, Hui Luo, Jian-Guo Cao, Lin-Fu Liang, Fan Yang and Yue-Wei Guo
Mar. Drugs 2023, 21(2), 69; https://doi.org/10.3390/md21020069 - 20 Jan 2023
Cited by 5 | Viewed by 2188
Abstract
The present investigation of the South China Sea soft coral Sarcophyton trocheliophorum resulted in the discovery of six new polyoxygenated diterpenes, namely sartrocheliols A–E (1, 3, 58) along with four known ones, 2, 4, 9 [...] Read more.
The present investigation of the South China Sea soft coral Sarcophyton trocheliophorum resulted in the discovery of six new polyoxygenated diterpenes, namely sartrocheliols A–E (1, 3, 58) along with four known ones, 2, 4, 9, and 10. Based on extensive spectroscopic data analysis, sartrocheliol A (1) was identified as an uncommon capnosane diterpene, while sartrocheliols B–E (3, 58) were established as cembrane diterpenes. They displayed diverse structural features not only at the distinctly different carbon frameworks but also at the various types of heterocycles, including the epoxide, γ-lactone, furan, and pyran rings. Moreover, their absolute configurations were determined by a combination of quantum mechanical-nuclear magnetic resonance (QM-NMR) approach, modified Mosher’s method, and X-ray diffraction analysis. In the anti-tumor bioassay, compound 4 exhibited moderate cytotoxic activities against A549, H1975, MDA-MB-231, and H1299 cells with the IC50 values ranging from 26.3 to 47.9 μM. Full article
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17 pages, 3156 KiB  
Article
Eremophilane-Type Sesquiterpenes from a Marine-Derived Fungus Penicillium Copticola with Antitumor and Neuroprotective Activities
by Jianping Zhang, Dong Liu, Aili Fan, Jian Huang and Wenhan Lin
Mar. Drugs 2022, 20(11), 712; https://doi.org/10.3390/md20110712 - 13 Nov 2022
Cited by 5 | Viewed by 2159
Abstract
Chemical examination of a marine sponge-associated Penicillium copticola fungus resulted in the isolation of ten undescribed eremophilanes, namely copteremophilanes A–J (110), along with two new glycosides, 5-glycopenostatin F (11) and 5-glucopenostatin I (12). Their structures [...] Read more.
Chemical examination of a marine sponge-associated Penicillium copticola fungus resulted in the isolation of ten undescribed eremophilanes, namely copteremophilanes A–J (110), along with two new glycosides, 5-glycopenostatin F (11) and 5-glucopenostatin I (12). Their structures were determined by extensive spectroscopic data, in association with ECD data and chemical conversions for configurational assignments. Analogs 1, 2, and 10 represent a group of uncommon skeletons of eremophilanes with an aromatic ring and a methyl migration from C-5 to C-9, and analogs 11 and 12 are characteristic of a PKS scaffold bearing a glucose unit. The incorporation of a chlorinated phenylacetic unit in 39 is rarely found in nature. Analog 7 showed neuroprotective effect, whereas 8 exhibited selective inhibition against human non-small cell lung cancer cells (A549). This study enriched the chemical diversity of eremophilanes and extended their bioactivities to neuroprotection. Full article
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