scholarly journals Unstable Tetramic Acid Derivatives from the Deep-Sea-Derived Fungus Cladosporium sphaerospermum EIODSF 008

Marine Drugs ◽  
2018 ◽  
Vol 16 (11) ◽  
pp. 448 ◽  
Author(s):  
Xiao Liang ◽  
Zhong-Hui Huang ◽  
Xuan Ma ◽  
Shu-Hua Qi
Keyword(s):  
Antibacterial Activity ◽  
Quantum Chemical Calculations ◽  
Acid Derivative ◽  
Deep Sea ◽  
Quantum Chemical ◽  
Spectroscopic Analysis ◽  
Fungal Strain ◽  
Cytotoxic Activities ◽  
Tetramic Acid ◽  
Cladosporium Sphaerospermum

Seven new unstable tetramic acid derivatives, cladosporiumins I-O (1–7), together with the known analogue cladodionen (8) were isolated from the extract of the deep-sea-derived fungus Cladosporium sphaerospermum EIODSF 008. Their structures were elucidated by spectroscopic analysis, quantum chemical calculations and ECD spectra. Compound 4 was a Mg complex of tetramic acid derivative. In acidic solvent, 4 could change to 1 and 6, and 7 could change to 5. In addition, 1, 5 and 8 existed as two exchangeable isomers, respectively. The structures of cladosporiumins E-H were reassigned as their Na complexes. The antibacterial and cytotoxic activities of 1–8 were also evaluated. However, because of their instability, all of the isolated compounds did not show significant antibacterial activity as the preliminary EtOAc extracts of the fungal strain.

scholarly journals Dechdigliotoxins A–C, Three Novel Disulfide-Bridged Gliotoxin Dimers from Deep-Sea Sediment Derived Fungus Dichotomomyces cejpii

Marine Drugs ◽  
2019 ◽  
Vol 17 (11) ◽  
pp. 596 ◽  
Author(s):  
Zhaoming Liu ◽  
Zhen Fan ◽  
Zhanghua Sun ◽  
Hongxin Liu ◽  
Weimin Zhang
Keyword(s):  
Tumor Cell ◽  
Quantum Chemical Calculations ◽  
Cell Lines ◽  
Deep Sea ◽  
Quantum Chemical ◽  
Biosynthetic Pathway ◽  
Spectroscopic Analysis ◽  
Tumor Cell Lines ◽  
Disulfide Linkage ◽  
Deep Sea Sediment

Dechdigliotoxins A–C (1–3), which represented the first examples of gliotoxin dimers with an unprecedented exocyclic disulfide linkage, were obtained from a deep-sea derived fungus Dichotomomyces cejpii FS110. The structures of these compounds were elucidated on the basis of spectroscopic analysis and the absolute configurations were unambiguously determined through quantum chemical calculations, as well as DP4+ probability simulations. The proposed biosynthetic pathway suggested 1–3 were generated from unusual L-Phe and D-Ser. All the isolates were evaluated for their cytotoxicity against four tumor cell lines.

A theoretical study on the size-dependence of ground-state proton transfer in phenol–ammonia clusters

2018 ◽  
Vol 20 (5) ◽  
pp. 3265-3276 ◽  
Author(s):  
Toshihiko Shimizu ◽  
Kenro Hashimoto ◽  
Masahiko Hada ◽  
Mitsuhiko Miyazaki ◽  
Masaaki Fujii
Keyword(s):  
Proton Transfer ◽  
Quantum Chemical Calculations ◽  
Ground State ◽  
Quantum Chemical ◽  
Size Dependence ◽  
Spectroscopic Analysis ◽  
Theoretical Study ◽  
Critical Size ◽  
Ir Spectroscopic ◽  
Ammonia Clusters

Quantum chemical calculations indicate that the critical size of GSPT is n = 9, supporting the IR spectroscopic analysis.

scholarly journals Hybrid Polyketides from a Hydractinia-Associated Cladosporium sphaerospermum SW67 and Their Putative Biosynthetic Origin

Marine Drugs ◽  
2019 ◽  
Vol 17 (11) ◽  
pp. 606 ◽  
Author(s):  
Seoung Rak Lee ◽  
Dahae Lee ◽  
Hee Jeong Eom ◽  
Maja Rischer ◽  
Yoon-Joo Ko ◽  
...  
Keyword(s):  
Cell Viability ◽  
Quantum Chemical ◽  
Cell Damage ◽  
2D Nmr ◽  
Positive Control ◽  
Marine Fungus ◽  
Geometric Isomers ◽  
Tetramic Acid ◽  
Cladosporium Sphaerospermum ◽  
Modified Mosher’S Method

Five hybrid polyketides (1a, 1b, and 2–4) containing tetramic acid core including a new hybrid polyketide, cladosin L (1), were isolated from the marine fungus Cladosporium sphaerospermum SW67, which was isolated from the marine hydroid polyp of Hydractinia echinata. The hybrid polyketides were isolated as a pair of interconverting geometric isomers. The structure of 1 was determined based on 1D and 2D NMR spectroscopic and HR-ESIMS analyses. Its absolute configuration was established by quantum chemical electronic circular dichroism (ECD) calculations and modified Mosher’s method. Tetramic acid-containing compounds are reported to be derived from a hybrid PKS-NRPS, which was also proved by analyzing our 13C-labeling data. We investigated whether compounds 1–4 could prevent cell damage induced by cisplatin, a platinum-based anticancer drug, in LLC-PK1 cells. Co-treatment with 2 and 3 ameliorated the damage of LLC-PK1 cells induced by 25 μM of cisplatin. In particular, the effect of compound 2 at 100 μM (cell viability, 90.68 ± 0.81%) was similar to the recovered cell viability of 88.23 ± 0.25% with 500 μM N-acetylcysteine (NAC), a positive control.

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