scholarly journals Density Functional Theory (DFT)-Aided Structure Elucidation of Linear Diterpenes from the Irish Brown Seaweed Bifurcaria bifurcata

Marine Drugs ◽  
2021 ◽  
Vol 19 (1) ◽  
pp. 42
Author(s):  
Vangelis Smyrniotopoulos ◽  
Daria Firsova ◽  
Howard Fearnhead ◽  
Laura Grauso ◽  
Alfonso Mangoni ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
Optical Rotation ◽  
Brown Seaweed ◽  
Cancer Cell Line ◽  
Structural Diversity ◽  
2D Nmr ◽  
Bifurcaria Bifurcata ◽  
Chcl3 Extract ◽  
Ic50 Values

Brown alga Bifurcaria bifurcata is an extraordinarily rich source of linear (acylic) diterpenes with enormous structural diversity. As part of our interest into secondary metabolites of the Irish seaweeds, here we report four new acyclic diterpenes (1–4) and seven known terpenoids (5–11) from the CHCl3 extract of B. bifurcata. The planar structures of the new metabolites were elucidated by means of 1D and 2D NMR, HRMS, and FT-IR spectroscopy. Since linear diterpenes are highly flexible compounds, the assignment of their stereochemistry by conventional methods, e.g., NOESY NMR, is difficult. Therefore, we employed extensive quantum-mechanical prediction of NMR chemical shifts and optical rotation analyses to identify the relative and absolute configurations of the new compounds 1–4. Several compounds moderately inhibited the human breast cancer cell line (MDA-MB-231) with IC50 values ranging from 10.0 to 33.5 μg/mL. This study not only demonstrates the vast capacity of the Irish B. bifurcata to produce highly oxygenated linear diterpenoids, but also highlights the potential of new methodologies for assignment of their stereogenic centers.

scholarly journals Oxygenated Acyclic Diterpenes with Anticancer Activity from the Irish Brown Seaweed Bifurcaria bifurcata

Marine Drugs ◽  
2020 ◽  
Vol 18 (11) ◽  
pp. 581
Author(s):  
Vangelis Smyrniotopoulos ◽  
Christian Merten ◽  
Daria Firsova ◽  
Howard Fearnhead ◽  
Deniz Tasdemir
Keyword(s):  
Cell Line ◽  
Brown Seaweed ◽  
Cancer Cell Line ◽  
Structural Diversity ◽  
Chemical Study ◽  
2D Nmr ◽  
Chemical Structures ◽  
Bifurcaria Bifurcata ◽  
Ic50 Values ◽  
Ft Ir

Brown alga Bifurcaria bifurcata is a prolific source of bioactive acyclic (linear) diterpenes with high structural diversity. In the continuation of our investigations on Irish brown algae, we undertook an in-depth chemical study on the n-hexanes and chloroform subextracts of B. bifurcata that led to isolation of six new (1–6) and two known (7–8) acyclic diterpenes. Chemical structures of the compounds were elucidated by a combination of 1D and 2D NMR, HRMS, FT-IR, [α]D and vibrational circular dichroism (VCD) spectroscopy. Compounds 1–8, as well as three additional linear diterpenes (9–11), which we isolated from the same seaweed before, were tested against the human breast cancer cell line (MDA-MB-231). Several compounds moderately inhibited the growth of the MDA-MB-231 cell line with IC50 values ranging from 11.6 to 32.0 μg/mL. The present study carried out on the lipophilic extracts of the Irish B. bifurcata shows the enormous capacity of this seaweed to produce a large palette of acyclic diterpenes with diverse oxygenation and substitution patterns and promising bioactivities.

scholarly journals Cytospyrone and Cytospomarin: Two New Polyketides Isolated from Mangrove Endophytic Fungus, Cytospora sp.

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4224
Author(s):  
Chengwen Wei ◽  
Qin Deng ◽  
Mengyu Sun ◽  
Jing Xu
Keyword(s):  
Density Functional ◽  
Human Cancer ◽  
Optical Rotation ◽  
Cancer Cell Line ◽  
Positive Control ◽  
Functional Theory ◽  
Spectroscopic Analyses ◽  
Mangrove Endophytic Fungus ◽  
Ic50 Value ◽  
Ic50 Values

Two new polyketides, cytospyrone (1), cytospomarin (2), together with three known metabolites dimethoxyphtalide (3), integracin A (4) and integracin B (5), were isolated from the culture of Cytospora sp. from the Chinese mangrove Ceriops tagal. Their structures were elucidated by extensive spectroscopic analyses and time dependent density functional theory (TDDFT), calculation of electronic circular dichroism (ECD) and optical rotation (OR) data. Compound 2 displayed weak inhibitory activity against Escherichia coli GIM1.201 (minimum inhibitory concentration (MIC) value of 0.35 mM). Compounds 4 and 5 displayed significant cytotoxicity against human cancer cell line HepG2 (IC50 values of 5.98 ±  0.12 µM and 9.97 ± 0.06 µM, respectively), more potent than the positive control 5-fluorouracil (IC50 value of 43.50 ± 3.69 µM).

NMR spectroscopy of the phenyl derivative of germanium(IV) 5,10,15-tritolylcorrole

2016 ◽  
Vol 20 (01n04) ◽  
pp. 525-533
Author(s):  
Giampaolo Ricciardi ◽  
Daniel O. Cicero ◽  
Sara Lentini ◽  
Sara Nardis ◽  
Roberto Paolesse ◽  
...  
Keyword(s):  
Density Functional ◽  
Chemical Shifts ◽  
2D Nmr ◽  
Functional Theory ◽  
Phenyl Derivative ◽  
Shielding Constants ◽  
Shielding Tensor ◽  
Experimental Values ◽  
Molecular And Electronic Structure

A thoroughly structural characterization of (TTC)GePh (TTC [Formula: see text] 5,10,15-tritolylcorrole; Ph [Formula: see text] phenyl) in solution has been carried out through a combination of 2D NMR (1H-1H COSY, 1H-1H ROESY, 1H-[Formula: see text]C HSQC and 1H-[Formula: see text]C HMBC) experiments and density functional theory (DFT) calculations of the molecular and electronic structure and the shielding constants. The 1H and [Formula: see text]C chemical shifts computed at DFT-S12g and DFT-SAOP levels of theory nicely reproduce the experimental values, the agreement between theory and experiment being especially good for the DFT-S12g results. The calculations prove to be able to capture the fine details of the NMR spectra and to resolve some assignment ambiguities related to the inherent conformational flexibility of the macrocycle. The calculations also provide an explanation of the observed chemical shift trends in terms of diamagnetic and paramagnetic components of the shielding tensor.

scholarly journals New Ophiobolin Derivatives from the Marine Fungus Aspergillus flocculosus and Their Cytotoxicities against Cancer Cells

Marine Drugs ◽  
2019 ◽  
Vol 17 (6) ◽  
pp. 346 ◽  
Author(s):  
Byeoung-Kyu Choi ◽  
Phan Thi Hoai Trinh ◽  
Hwa-Sun Lee ◽  
Byeong-Woo Choi ◽  
Jong Soon Kang ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Cell Lines ◽  
Cancer Cell ◽  
Chemical Shifts ◽  
Optical Rotation ◽  
2D Nmr ◽  
Cancer Cell Lines ◽  
Marine Fungus ◽  
Side Chain ◽  
Spectroscopic Methods

Five new sesterterpenes, 14,15-dehydro-6-epi-ophiobolin K (1), 14,15-dehydro- ophiobolin K (2), 14,15-dehydro-6-epi-ophiobolin G (3), 14,15-dehydro-ophiobolin G (4) and 14,15-dehydro-(Z)-14-ophiobolin G (5), together with four known ophiobolins (6–9) were isolated from the marine fungus Aspergillus flocculosus derived from the seaweed Padina sp. collected in Vietnam. The five new ophiobolins were first isolated as ophiobolin derivatives consisting of a fully unsaturated side chain. Their structures were elucidated via spectroscopic methods including 1D, 2D NMR and HR-ESIMS. The absolute configurations were determined by the comparison of chemical shifts and optical rotation values with those of known ophiobolins. All compounds (1–9) were then evaluated for their cytotoxicity against six cancer cell lines, HCT-15, NUGC-3, NCI-H23, ACHN, PC-3 and MDA-MB-231. All the compounds showed potent cytotoxicity with GI50 values ranging from 0.14 to 2.01 μM.

scholarly journals Powder Crystallography by Combining NMR and Crystal Structure Predictions

2014 ◽  
Vol 70 (a1) ◽  
pp. C136-C136 ◽  
Author(s):  
Cory Widdifield ◽  
Maria Baias ◽  
Jean-Nicolas Dumez ◽  
Per H. Svensson ◽  
Hugh Thompson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Chemical Shift ◽  
Structure Determination ◽  
Structure Prediction ◽  
Density Functional ◽  
De Novo ◽  
Chemical Shifts ◽  
2D Nmr ◽  
Other Information ◽  
13C Chemical Shift

State-of-the-art work in the field of NMR crystallography for molecular systems at natural abundance has recently focused on the accurate measurement of 1H chemical shift values. We will show how when coupled with crystal structure prediction (CSP) methods, this protocol is well-suited for solving the crystal structures of small to medium sized organic molecules, including cocaine and the de-novo structure determination of AZD8329.[1,2] As complementary 1D and 2D NMR experiments are needed for the 1H assignment process, other information, such as isotropic 13C chemical shift values (δiso) are measured. Unfortunately, 13C chemical shifts are not generally useful for structure determination. Additional NMR parameters that are sensitive to structure would ensure that the structure determination procedure is robust, and would provide more accurate refinements when studying larger or more challenging systems. Here, we measure 13C chemical shift tensors for a variety of prototypical organic pharmaceuticals and use density functional theory computations under the gauge-including projector augmented-wave (GIPAW) formalism to probe whether these parameters may be discriminatory for unit cell determinations and structure determination (notably when added to the CSP + 1H chemical shifts protocol).

scholarly journals Structure Revision and Protein Tyrosine Phosphatase Inhibitory Activity of Drazepinone

Marine Drugs ◽  
2021 ◽  
Vol 19 (12) ◽  
pp. 714
Author(s):  
Fei Cao ◽  
Li Pan ◽  
Wen-Bin Gao ◽  
Yun-Feng Liu ◽  
Cai-Juan Zheng ◽  
...  
Keyword(s):  
Detailed Analysis ◽  
Protein Tyrosine Phosphatase ◽  
Inhibitory Activity ◽  
Chemical Shifts ◽  
Tyrosine Phosphatase ◽  
2D Nmr ◽  
Nmr Data ◽  
Structure Revision ◽  
Ic50 Values

From the marine-derived fungus Penicillium sumatrense (Trichocomaceae), a pair of enantiomers [(+)-1 and (−)-1] were isolated with identical 1D NMR data to drazepinone, which was originally reported to have a trisubstituted naphthofuroazepinone skeleton. In this study, we confirmed the structures of the two enantiomers as drazepinone and revised their structures by detailed analysis of extensive 2D NMR data and a comparison of the calculated 13C chemical shifts, ECD, VCD, and ORD spectra with those of the experiment ones. (+)-1 and (−)-1 were evaluated for their PTP inhibitory activity in vitro. (−)-1 showed selective PTP inhibitory activity against PTP1B and TCPTP with IC50 values of 1.56 and 12.5 μg/mL, respectively.

scholarly journals Prenylated Phenol and Benzofuran Derivatives from Aspergillus terreus EN-539, an Endophytic Fungus Derived from Marine Red Alga Laurencia okamurai

Marine Drugs ◽  
2019 ◽  
Vol 17 (11) ◽  
pp. 605 ◽  
Author(s):  
Li ◽  
Li ◽  
Yang ◽  
Meng ◽  
Li ◽  
...  
Keyword(s):  
Endophytic Fungus ◽  
Density Functional ◽  
Aspergillus Terreus ◽  
Optical Rotation ◽  
2D Nmr ◽  
Red Alga ◽  
Spectrometric Data ◽  
Phenol Derivatives ◽  
First Time ◽  
Laurencia Okamurai

Three new prenylated phenol derivatives, terreprenphenols A–C (1–3), along with four known related compounds (4–7), were isolated from Aspergillus terreus EN-539, an endophytic fungus obtained from the marine red alga Laurencia okamurai. The structures of these compounds were established by extensive analysis of 1D/2D NMR data, mass spectrometric data, and optical rotation (OR). The corresponding relationship between absolute configuration and optical rotation for known compounds anodendroic acid (4) and asperterreusine C (5) was ambiguous in literature, and their absolute configurations were therefore discussed and confirmed for the first time by time-dependent density functional (TDDFT) ECD and OR calculations. Compounds 1–7 inhibited some common aquatic bacteria with MIC values ranging from 2 to 64 μg/mL.

scholarly journals Induction of Secondary Metabolites from the Marine-Derived Fungus Aspergillus versicolor through Co-cultivation with Bacillus subtilis

Planta Medica ◽  
2019 ◽  
Vol 85 (06) ◽  
pp. 503-512 ◽  
Author(s):  
Nada Abdel-Wahab ◽  
Sebastian Scharf ◽  
Ferhat Özkaya ◽  
Tibor Kurtán ◽  
Attila Mándi ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Circular Dichroism ◽  
Density Functional ◽  
2D Nmr ◽  
Fungal Culture ◽  
Aspergillus Versicolor ◽  
Electronic Circular Dichroism ◽  
Ic50 Values ◽  
Culture Extract ◽  
Circular Dichroïsm

AbstractA new cyclic pentapeptide, cotteslosin C (1), a new aflaquinolone, 22-epi-aflaquinolone B (3), and two new anthraquinones (9 and 10), along with thirty known compounds (2, 4 – 8, 11 – 34) were isolated from a co-culture of the sponge-associated fungus Aspergillus versicolor with Bacillus subtilis. The new metabolites were only detected in the co-culture extract, but not when the fungus was grown under axenic conditions. Furthermore, the co-culture extract exhibited an enhanced accumulation of the known constituents versicolorin B (14), averufin (16), and sterigmatocyctin (19) by factors of 1.5, 2.0, and 4.7, respectively, compared to the axenic fungal culture. The structures of the isolated compounds were elucidated on the basis of 1D and 2D NMR spectra and mass spectrometry as well as by comparison with literature data. The absolute configuration of compounds 3, 9, and 10 was determined by ECD (electronic circular dichroism) analysis aided by TDDFT-ECD (time-dependent density functional theory electronic circular dichroism) calculations. Compounds 15, 18 – 21, and 26 exhibited strong to moderate cytotoxic activity against the mouse lymphoma cell line L5178Y, with IC50 values ranging from 2.0 to 21.2 µM, while compounds 14, 16, 31, 32, and 33 displayed moderate inhibitory activities against several gram-positive bacteria, with MIC values ranging from 12.5 to 50 µM.

scholarly journals Azaphilones from the Red Sea Fungus Aspergillus falconensis

Marine Drugs ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 204 ◽  
Author(s):  
Dina H. El-Kashef ◽  
Fadia S. Youssef ◽  
Rudolf Hartmann ◽  
Tim-Oliver Knedel ◽  
Christoph Janiak ◽  
...  
Keyword(s):  
Red Sea ◽  
Cancer Cell Line ◽  
2D Nmr ◽  
X Ray Diffraction ◽  
2D Nmr Spectroscopy ◽  
Nmr Data ◽  
Ic50 Values ◽  
Rice Medium ◽  
Optical Rotations ◽  
New Compounds

The marine-derived fungus Aspergillus falconensis, isolated from sediment collected from the Canyon at Dahab, Red Sea, yielded two new chlorinated azaphilones, falconensins O and P (1 and 2) in addition to four known azaphilone derivatives (3−6) following fermentation of the fungus on solid rice medium containing 3.5% NaCl. Replacing NaCl with 3.5% NaBr induced accumulation of three additional new azaphilones, falconensins Q−S (7−9) including two brominated derivatives (7 and 8) together with three known analogues (10−12). The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopy and HRESIMS data as well as by comparison with the literature. The absolute configuration of the azaphilone derivatives was established based on single-crystal X-ray diffraction analysis of 5, comparison of NMR data and optical rotations as well as on biogenetic considerations. Compounds 1, 3−9, and 11 showed NF-κB inhibitory activity against the triple negative breast cancer cell line MDA-MB-231 with IC50 values ranging from 11.9 to 72.0 µM.

scholarly journals Pyrenosetin D, a New Pentacyclic Decalinoyltetramic Acid Derivative from the Algicolous Fungus Pyrenochaetopsis sp. FVE-087

Marine Drugs ◽  
2020 ◽  
Vol 18 (6) ◽  
pp. 281
Author(s):  
Bicheng Fan ◽  
Pradeep Dewapriya ◽  
Fengjie Li ◽  
Laura Grauso ◽  
Martina Blümel ◽  
...  
Keyword(s):  
Cell Line ◽  
Acid Derivative ◽  
Optical Rotation ◽  
Chemical Study ◽  
2D Nmr ◽  
Human Malignant Melanoma ◽  
Chemical Structures ◽  
Isolation And Characterization ◽  
Ic50 Values ◽  
Fungal Genus

The fungal genus Pyrenochaetopsis is commonly found in soil, terrestrial, and marine environments, however, has received little attention as a source of bioactive secondary metabolites so far. In a recent work, we reported the isolation and characterization of three new anticancer decalinoyltetramic acid derivatives, pyrenosetins A–C, from the Baltic Fucus vesiculosus-derived endophytic fungus Pyrenochaetopsis sp. FVE-001. Herein we report a new pentacyclic decalinoylspirotetramic acid derivative, pyrenosetin D (1), along with two known decalin derivatives wakodecalines A (2) and B (3) from another endophytic strain Pyrenochaetopsis FVE-087 isolated from the same seaweed and showed anticancer activity in initial screenings. The chemical structures of the purified compounds were elucidated by comprehensive analysis of HR-ESIMS, FT-IR, [α]D, 1D and 2D NMR data coupled with DFT calculations of NMR parameters and optical rotation. Compounds 1–3 were evaluated for their anticancer and toxic potentials against the human malignant melanoma cell line (A-375) and the non-cancerous keratinocyte cell line (HaCaT). Pyrenosetin D (1) showed toxicity towards both A-375 and HaCaT cells with IC50 values of 77.5 and 39.3 μM, respectively, while 2 and 3 were inactive. This is the third chemical study performed on the fungal genus Pyrenochaetopsis and the first report of a pentacyclic decalin ring system from the fungal genus Pyrenochaetopsis.

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